JP2003520978A - Compression-tuned Bragg gratings and lasers - Google Patents

Abstract

Abstract: A compression tunable Bragg grating comprises tunable optical elements 20,600, wherein the optical fiber comprises at least one Bragg grating (12) inscribed therein. 10) is a large diameter waveguide housed and fused in at least a portion of a glass capillary (20) or provided with a core and a large cladding. The light (14) is incident on the diffraction grating (12), and the light (16) is reflected at a reflection wavelength λ1. The axial compression of the tunable elements 20, 600 shifts the reflection wavelength of the diffraction grating (12) without buckling of the elements. The shape of the element can be other shapes (e.g., a "dogbone" shape), and / or multiple gratings or paired gratings can be utilized, and multiple fibers can be used. It is also possible to use (10) or the core (612). By doping between at least one pair of diffraction gratings (150, 152) in the device, a compression tunable laser can be constructed, wherein the diffraction grating (12) or the diffraction gratings (150, 152) It is also possible to configure a tunable DFB laser. Furthermore, the element (20) can be provided with an inner tapered region (22) or a tapered (flute-shaped) portion (27). Compression can be performed using PZT, a stepper motor, or other actuator or fluid pressure.

Description

Detailed Description of the Invention

[0001]

[Cross reference with related applications]

This application is directed to US patent application Ser. No. 09 / 205,9 filed December 4, 1998.
U.S. Patent Application No. 09, filed September 20, 1999, which is a continuation of part No. 43.
Part of the contents of / 400,362 will be continued. Further, co-pending U.S. patent application entitled "Bragg Grating Pressure Sensor" (Sidra Specification C
C-0036B), U.S. Patent Application No. (Sidra Specification CC-078B) entitled "Fiber Grating Encased in Tube", entitled "Optical Waveguide with Large Diameter, Diffraction Grating, Laser". US Patent Application No. (Sidra Specification No. CC-02
No. 30) is all filed at the same time as this application and includes the content disclosed in this application.

[0002]

【Technical field】

The present invention relates to fiber gratings, and more particularly to compression tuned black gratings and lasers.

[0003]

[Background technology]

It is well known in the optical fiber art that a Bragg diffraction grating embedded in the fiber can be used in a compressed state to function as a tunable filter or a tunable laser. In this regard, U.S. Pat. No. 5,469,52 entitled "Compression Tunable Fiber Grating".
No. 0, US Pat. No. 5,691,99 entitled “Compression-tuned Fiber Laser”
No. 9 is disclosed, and these can be referred to.

In order to prevent the buckling of the fiber under compression, the technique disclosed in the above-mentioned US Pat. No. 5,469,520 and US Pat. No. 5,691,999. Utilizes a sliding ferrule around the fiber and the diffraction grating to position the ferrule within a mechanical structure for guiding, aligning and receiving the ferrule and the fiber. However, it is desirable to have a configuration that allows the fiber grating to be compressed without buckling, using a sliding ferrule, and without requiring such a mechanical structure.

Further, as disclosed in US Pat. No. 5,042,898 entitled “Built-in Bragg Filter Temperature Compensated Optical Waveguide Device” by Morley et al., An optical fiber diffraction grating is made of glass. It is known to be housed inside a pipe to prevent buckling under compression and thereby provide a wavelength compensated temperature compensated fiber Bragg grating. However, with such techniques, creep occurs between the fiber and the tube over time, in high temperature environments, or under extensive compression.

[0006]

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a fiber grating arrangement capable of compression tuning the grating without creeping and without the need for a sliding ferrule or mechanical support structure for such a ferrule. That is. According to the present invention, a compression tuned fiber optic device comprises a tunable optical element internally having at least one reflective element along a longitudinal axis, the cross section of at least a portion of said element comprising: It is continuous and is composed of substantially the same material.

Further in accordance with the present invention, the tunable element comprises an optical fiber having a reflective element embedded therein and a tube containing the optical fiber and the reflective element along a longitudinal axis. The tube is fusion bonded to at least a portion of the fiber.
Further in accordance with the present invention, the tunable element comprises a large diameter optical waveguide having an outer cladding and an inner core therein, the waveguide having an outer diameter of at least 0.3 mm. There is.

Further according to the invention, the material is a glass material. Further in accordance with the invention, the tube is fused to the area of the optical fiber where the reflective element is present.
Further in accordance with the invention, a plurality of optical fibers or cores are disposed inside the tunable element. Further according to the invention, said tunable element comprises:
A plurality of reflective elements are contained within the tube. Further in accordance with the present invention, at least one pair of reflective elements is provided inside the tunable element and a rare earth dopant is doped between at least the pair of elements of the tunable element. , A laser is constructed. Further in accordance with the present invention, the laser wavelength of the laser changes as the load on the tube changes.

The present invention provides a Bragg grating disposed inside a tunable optical element. It consists of an optical fiber fused to at least part of a glass capillary (tube-containing diffraction grating) or a waveguide grating with a large diameter with an optical core and large cladding. ing. The compression of such a tunable element tunes the reflection wavelength of the diffraction grating without causing buckling of the element.

The device can be formed from a glass material such as silica. The shape of the tunable element can be any other shape (eg dogbone shape) that can be easily scaled to obtain the desired sensitivity as well as improved sensitivity of wavelength shift to load. Is. The invention makes it possible to tune the wavelength of the fiber grating or the laser with very high reproducibility and without much creep and hysteresis. It is also possible to place one or more diffraction gratings, fiber lasers, or multiple fibers or optical cores inside the tunable element.

Diffusing the tube by fusing the tube to the grating region of the fiber, and / or to the axial ends on either side of the grating region, adjacent to the grating or at a distance from the grating. "Housing" the grating or laser in the tube
It is possible. The one or more diffraction gratings or lasers can be fusion welded to the interior of the tube, or only a portion can be welded to the interior of the tube or to the outer surface of the tube. Furthermore, one or more waveguides and / or
Alternatively, the tunable element can be constructed by axially fusion-bonding and optically coupling the tube-containing fiber / diffraction grating.

The above as well as other objects, features, and advantages of the present invention will become more apparent in the following detailed description of the embodiments.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, a compression-tuned Bragg grating is provided in a well-known optical waveguide 10 (e.g., a standard telecommunication single-mode optical fiber).
It is composed of engraved (or embedded or drawn) objects. The fiber 10 has an outer diameter of about 125 microns and is made of silica glass (SiO2) containing a suitable dopant as is well known.
It is possible to propagate the light 14 along 0. Bragg diffraction grating 12
Is, as is well known, a periodic or aperiodic variation in the effective refractive index and / or the effective optical absorption coefficient of the optical waveguide. As an example of such a diffraction grating 12,
U.S. Pat. Nos. 4,725,110 and 4,807,950 entitled "Method of Engraving Diffraction Grating Inside Optical Fiber" given to Glenn et al., "Aperiodic Inside Optical Fiber" given to Glenn And apparatus disclosed in US Pat. No. 5,388,173 entitled "Method and Apparatus for Forming Dynamic Diffraction Grating". These patents disclose this point and can be referred to for an understanding of the present invention.

However, any type of wavelength tunable diffraction grating or reflective element embedded, etched, drawn, or otherwise formed within fiber 28 may be utilized as desired. can do. In the present application, “
The term "grating" refers to all of these reflective elements. Further, the reflective element (or diffraction grating) 12 can be utilized to reflect and / or transmit light.

If desired, the materials and dimensions of the optical fiber or optical waveguide 10 can be different. For example, fiber 10 can be formed from any glass (eg, silica, phosphate glass, etc.), or can be formed from glass and synthetic resin, or only synthetic resin. For high temperature applications, optical fibers made of glass materials are desirable. Furthermore, the outer diameter of the optical fiber 10 is set to 8
It may be 0 micron or any other size. Further, any optical waveguide can be used instead of the optical fiber. For example, multimode (multi
-mode waveguide, birefringent waveguide, polarization-maintaining (polarization main)
taining) waveguide, polarization waveguide, optical waveguide with multiple cores,
It is also possible to use an optical waveguide having a plurality of claddings, a flat waveguide, a planar optical waveguide (rectangular waveguide) or another optical waveguide. In the present application, “
The term "fiber" includes the optical waveguides described above.

The light 14 is incident on the diffraction grating 12, where a portion thereof having a predetermined light wavelength band centered on the reflection wavelength λb is reflected as shown in line 16 and the rest of the incident light. The wavelength (which is within the predetermined wavelength range) is transmitted as shown by line 18.

As will be described in detail below, the fiber 10 having the diffraction grating 12 therein includes:
It is housed and fused to at least a part of the cylindrical capillary 20 made of glass.
The tube 20 is axially compressed by a compression mechanism or housing 50. Tube 2
The other end of 0 is pressed against the seat 51 at the end 52 of the housing 50.
The housing 50 further includes a pair of arms (which guide the movable block 56).
That is, the side portion) 54 is provided. The block 56 includes a sheet 57 that is pressed against the other end of the tube 20. Holes 58 are drilled in end 52 and block 56 to allow fiber 10 to pass therethrough.
An actuator 60 (eg, a stepper electric motor, or other type of electric motor capable of controlling rotation and position) has a mechanical link 62 (eg, a screw drive, a linear actuator, gears and / or By being connected to the movable block 56 by a cam, the block 5
6 is adapted to move as indicated by arrow 64. Therefore, the load applied to the block can be set to a predetermined magnitude by the stepper motor 60, whereby the tube 20 can be compressed and the reflection wavelength of the diffraction grating 12 can be set to a desired wavelength. Instead of providing the retracted seats 51, 57, it is possible to contact the tubes 20 so that they are flush with the ends 52, 56. As the stepper electric motor 60, it is possible to use a stepper electric motor driven in a minute step mode and having high resolution. As an example of such an electric motor, one described in the above-mentioned US Pat. No. 5,469,520 named "Compression Tuning Fiber Diffraction Grating" to Morley et al. (For example, Melles Griot). ) Nano mover (NANOMOVER) manufactured by the company. This patent discloses this point. Other high-resolution or low-resolution stepper motors can be used as desired. The stepper motor 60 is driven by the control circuit 63. The control circuit 63 outputs to the line 61 a drive signal required to drive the stepper motor 60, and thus the block 56, to a desired position and set the Bragg wavelength λb of the diffraction grating 12 to a desired value. Other actuators may be utilized in place of the stepper motor, if desired, as described below with respect to FIG.

As shown in FIG. 2, instead of using the moveable block 56, it is possible to utilize a housing 70 having two end caps 72, 74 and an outer wall 76. In such a case, the holes 58 are provided in the end caps 72 and 74 so that the fiber 10 can be extended to the outside. The stepper motor 62 is connected to the end cap 74 by a mechanical link 62. When the end cap 74 is pushed by the step electric motor 62, the wall portion 76 is compressed or distorted, the tube 20 is compressed, and the reflection wavelength of the diffraction grating 12 is shifted.

In another embodiment of the present invention, as shown in FIG. 3, a cylindrical housing 90
Is used. The cylindrical housing 90 comprises an outer cylindrical wall 98, two end caps 95, and two inner cylindrical parts (or pistons) 92, one end of each of which is one end cap 95. Are linked to. The tube 20 (with the diffraction grating housed therein) is in contact with the other ends of the two pistons 92 and is arranged between them. If desired, the cross-sectional shape and / or side cross-sectional shape of the members 98, 95, 92 of the housing 90 can be different. The end cap 95 can be a separate member or can be a continuous member with the piston 92 and / or the outer cylindrical member 98.

An external axial load is applied to the end cap 95 on the left side of the housing 90 by the stepper motor 60. Piston 92 includes a bore 94 having a diameter large enough to allow fiber 10 to pass through.

The outer shape of the wall portion 98 and the outer shape of the tube 20 form an I-shaped compartment 100. The piston 92, the outer cylindrical wall 98 and the tube 20 can be made of the same material or different materials.

Examples of available dimensions of the housing 90 are given below. Other dimensions can be used. The tube 20 has an outer diameter d2 of about 2 mm (0.07 inch) and a length L1 of about 12.5 mm (0.5 inch). Each piston 92 has an outer diameter d5 of about 19.1 mm (0.75 inch) and a length L5 of about 6.25 cm (2.55 cm).
Inches). The diameter of the hole 94 of the piston 92 is about 1 mm (1000 microns), and the total length L4 of the housing 90 is about 12.7 cm (5 inches).
The thickness t1 of the outer wall portion 98 is about 1.0 mm (0.04 inch), and the gap g1 between the inner diameter of the outer wall portion 98 and the outer diameter of the piston 92 is about 1.52 mm (0
． 06 inches).

The dimensions, materials and material properties of the wall 98 and piston 92 (eg, Poisson's ratio, Young's modulus, coefficient of thermal expansion and other well-known properties) so that the external strain causes the desired strain in the capillary 20. , Can be selected. The resolution and setting range for setting the reflection wavelength can be determined by controlling these parameters. For example, increasing the total length L4 increases the sensitivity ΔL / L.

In particular, when the axial load generated from the stepper motor increases, the outer wall portion 98 compresses and / or distorts, thereby reducing the axial length L4 of the housing 90 by a predetermined amount ΔL. In this case, since the tube is compressed, a predetermined portion ΔL ′ of the total amount of change in the axial length appears in the tube 20. The compression of the tube 20 reduces the Bragg reflection wavelength λ1 of the diffraction grating 12 by a predetermined amount, which shifts the wavelength. When the spring constant of the piston 92 is larger than that of the glass tube 20, the amount of compression of the tube 20 under a predetermined load is larger than that of the piston 92. Further, when a predetermined external load is applied, a predetermined amount of the external load is applied to the outer wall portion 98, and the remaining load is applied to the pipe 20.

For example, if the wall 98, piston and end cap 95 are all made of titanium and have the dimensions described above, under an external load of 2200 lbf, a load of about 2000 lbf will be applied to the outer wall 98. (Ie, compressing and / or distorting outer wall 98), a load of about 200 lbf is applied to tube 20. The cylindrical wall portion 98 is a diaphragm (d) that compresses or distorts when external pressure increases.
iaphram) or bellows.

The housing 90 can be assembled such that the tube 20 is pre-strained before an external load is applied, or the housing 90 can be assembled so that the tube 20 is not pre-strained. It is possible.

The housing 50, 70, 90 and / or one or more of these components may be metal (eg, titanium), nickel-rich alloys (eg, varying amounts of nickel, carbon, chromium, iron, Inconel (R), Incoloy (R), Nimonic (R)) containing molybdenum and titanium, steel, glass materials (e.g., those described above for tube 20), or other high strength,
It can be formed of a metal or an alloy having corrosion resistance and heat resistance. Other materials can be used as long as they have sufficient strength to compress the tube 20. Inconel, Incoloy and Nimonic are registered trademarks of Inco Alloys International Inc. If desired, other materials having other properties can be utilized, depending on the application.

As an alternative embodiment, as shown in FIG. 14, instead of utilizing a stepper motor as an actuator, another actuator 154 may be used to guide the tube 20.
Can also be compressed. Examples of other actuators 154 include peizoelectric actuators, solenoids, pneumatic actuators, or other devices capable of exerting axial compressive forces directly or indirectly on tube 20. To be The actuator 154 has a housing 150.
A load is applied to a movable block 152 (similar to the movable block 56 of FIG. 1) that can be placed on the same (similar to the frame 50 of FIG. 1) and moves in the direction of arrow 155. To function.

One end of the tube 20 has a seat 51 provided at an end 153 of the housing 150.
Pressed against. The housing 150 further includes a pair of side portions 157 that guide the movable block 152. One side 157 may be omitted if desired. The block 152 includes a seat 57 that is pressed against the other end of the tube 20.

Further, the actuator 154 is connected to the control circuit 158 and is connected to the pipe 20.
The control circuit 158 outputs a signal necessary for setting the load applied to the beam to a desired value to set the Bragg wavelength λb of the diffraction grating 12 to the desired wavelength to the actuator 154 via the line 156. In open loop configuration, controller 158
Signal to the actuator 154 via line 156 (eg, electrical voltage)
By outputting, the load can be set. As an alternative embodiment, in a closed loop configuration of actuator 154, the load may be set by outputting a signal to actuator 154 via line 156 and detecting the load or position of actuator 154 via line 160. It is possible.

In the case of a design in which only one end is provided, the fiber 10 is inserted into the housing 15
It is inserted into one end of 0 and penetrates the hole 162 in the end portion 153. If a through-type (fiber has both ends) design is utilized, the block 152 may be provided with a hole 164 extending through some or all of it, with the other end of the fiber 10 emerging from its side, or It is also possible to penetrate the hole 166 in the actuator 154 and insert it into the other end of the housing 150.

As an example of a closed loop piezo electric actuator that can be used, model numbers CM (controller) and DPT-CM (for cylindrical actuator) manufactured by Queensgate, Inc. of New York are available. Can be mentioned. It is also possible to use other actuators such as those mentioned above.

As an alternative embodiment, as shown in FIG.
4 and it is possible to set the wavelength of the diffraction grating by applying a fluid pressure to the tube 20. This is a co-pending U.S. patent application Ser. No. 0, filed December 4, 1998, entitled "Fiber Grating Pressure Sensor Encased in Tube".
It is similar to the pressure sensor disclosed in 9 / 205,944. This patent application discloses this point, and the shape and configuration of the tube 20 can use the ones described therein. The housing 172 has a compartment 176.
And has an opening 178. The opening 178 communicates with a pressure source 180 that strictly generates a source pressure. The compartment 176 can be filled with a fluid (eg, one or more types of gas and / or liquid). Tube 20 can be attached to wall 175 or suspended in fluid 176. The optical fiber 10 is passed through the compartment via a well-known hermetic feedthrough and is provided with some slacks 179 to allow the tube 20 to be compressed over a wide pressure range. ing. Similar to the actuator embodiment described above, the reflection wavelength of the diffraction grating changes as the pressure P _S changes. However, in such a case, the wavelength of the diffraction grating is set by setting a predetermined source fluid pressure P _S.

As shown in FIG. 16, for example, the pressure source 180 may be provided with a hydraulic actuator, that is, a piston 300 arranged inside the compartment 301. The piston 300 has a well-known hydraulic drive mechanism 304 by a mechanical link 302.
Are linked to. The hydraulic drive mechanism 304 sets the pressure P _S by strictly setting the position of the piston 300. The hydraulic drive mechanism 304 can be electronically controlled by a well-known control circuit 308 (similar to controller 158 (FIG. 14)). A position command signal is output from the control circuit 308 to the hydraulic controller 304 via the line 306 to set a specific piston position, and thus a pressure P _S , thereby setting the wavelength of the diffraction grating λb. Is set. If desired, other well known pressure sources can be used to set the wavelength of the diffraction grating. The housings 50, 150, 70 described in this application,
The cross section of 90, and these components (including moveable blocks 56, 152), can be circular or other shapes (eg, square, square, etc.).

A method for compressing the tube 20 of the present invention has been described with respect to the particular embodiment shown in FIGS. 1-3, 14 and 15, but for compressing the tube axially. Then, any device or fixture can be used to compress the tube 20 and tune the reflected wavelength of the diffraction grating 12 to the desired wavelength. In the present invention, it is not necessary to strictly limit the hardware configuration.

In all of the embodiments disclosed herein, stress is applied to the sheet (56, 50, 92, 74, 72, 153, 159) of the axial end surface of the tube 20 and / or the surface engaging it. Plates of material may be applied to reduce or improve the engagement of the tube 20 with the sheet of engagement surfaces. Referring to FIG. 4, the outer diameter d1 of the tube 20 is about 3
mm, and the length L1 is about 10 to 30 mm. The length Lg of the diffraction grating 12 is about 5 to 15 mm. As an alternative embodiment, the length L1 of the tube 20 is changed to the length L of the diffraction grating by increasing the length of the diffraction grating or using a short tube.
It is also possible to make it almost the same as g. Other sizes and lengths of the tube 20 and the diffraction grating 12 are possible. Further, the optical fiber 10 and the diffraction grating 12 do not have to be fusion-welded to the central portion of the tube 20, but can be fused to any portion of the tube 20. Also, it is not necessary to melt the fiber 10 over the entire length of the tube 20.

The dimensions and shapes described in connection with the embodiments of the present application are merely exemplary and, if necessary, based on the teachings of the present application, requirements for use, size, performance or manufacturing, or The dimensions can be different to accommodate other factors.

The tube 20 is made of a glass material. Examples of such glass materials are natural quartz, synthetic quartz, fused silica, silica (SiO2), Pyrex (registered trademark) manufactured by Corning (borosilicate), Vycor (registered trademark) manufactured by Corning. ) (Consisting of 95% silica and 5% other constituents such as boron oxide) and the like. As the material of the tube, the inner diameter of the tube 20 and the fiber 1 are used.
There is no interface with the outer diameter of 0 (ie the inner diameter of the tube 20 is
Tube 20 (ie, cannot be identified as and is part of the cladding of
A material capable of fusion-welding (forming a molecular bond, that is, melting together) to the outer surface (that is, the cladding) of the optical fiber 10 should be used.

To match the thermal expansion of the tube 20 with the fiber 10 over a wide temperature range,
The coefficient of thermal expansion (CTE) of the material of the tube 20 should be approximately matched to the CTE of the material of the fiber 10 (for example using a tube of fused silica and an optical fiber).
. In general, the lower the melting temperature of a glass material, the higher the CTE. Therefore, silica fiber (high melting temperature and low CTE) and Pyrex (registered trademark)
And a tube made of another glass material such as Vycor (which has a low melting temperature and a high CTE), the thermal expansion between the tube 20 and the fiber 10 over a wide temperature range. Cannot be matched. However, it is not necessary here for the CTE of the fiber 10 and the CTE of the tube 20 to be matched (described in more detail below).

A tube 20 made of another elastically deformable material may be used instead of the glass material tube 20 as long as it can be fused to the fiber 10.
For example, when the optical fiber is made of synthetic resin (plastic), a tube made of synthetic resin material can be used.

At the axial end of the tube 20 (where the fiber 10 exits the tube 20), the fiber 1
An inner region 22 can be provided that is spaced from the fiber 10 by tapering (ie flaring) inwardly, for relief of zero strain, or for other reasons. In such a case, in the region 28 between the tube 20 and the fiber 10,
It is possible to fill the strain relief filler material (eg, polyimide, silicon, etc.). Further, a seat portion for engaging with another member (not shown)
To the pipe 20 and / or the angle at which the pipe 20 is loaded (force angl
It is also possible to provide the pipe 20 with a tapered (i.e. chamfered or beveled) outer corner (i.e. end) 24 for adjusting e) or for other reasons. The angle of the chamfered corner portion 24 is determined so as to obtain a desired function. Furthermore, the cross-sectional shape of the pipe 20 can be a shape other than a circle (for example, a square, a rectangle, an ellipse, a clamshell shape, etc.), and the side cross-sectional shape is a shape other than a square (for example, a circle, a square). , Oval, clamshell, etc.).

As an alternative embodiment, instead of providing an inner tapered region 22, one or both axial ends of the tube (where fiber 10 exits tube 20), as indicated by dashed line 27, It is also possible to provide an axially tapered (ie fluted, conical, nippled) axial portion. Such a tapered portion has a contour that gradually decreases toward the fiber 10 (described in detail below with respect to FIG. 12). The provision of such a flute-like portion 27 allows the boundary 10 (when the fiber 10 is pulled along its longitudinal axis) to
It has been found that the tensile strength of the fiber 10 exiting the tube 20) and its vicinity is increased (eg, 6 lbf or more).

When the fiber 10 is projected beyond the tube 20, the outer protective buffer layer 21 may be provided on the fiber 10 to prevent damage to the outer surface of the fiber 10. Such a buffer layer 21 can be formed of polyimide, silicon, Teflon (polytetraflouroethylene), carbon, gold, and / or nickel and has a thickness of about 25 microns. The thickness of the buffer layer 21 and the buffer material may be different. If an inner tapered region 22 is provided and is large enough, a buffer layer 21 can be inserted into this region 22 to convert exposed fibers into protected fibers. As an alternative example, if the outer tapered section 27 is provided at the axial end of the tube 20, the buffer layer begins where the fiber exits the outer tapered section 27. If the buffer is provided from a location spaced from the location where the fiber exits, the fiber 10
It is possible to further coat the exposed part of the with an additional buffer layer (not shown).
Such an additional buffer layer is capable of covering the exposed fibers on the outside of the tube 20, and the buffer layer 21 and / or the tapered portion 2 of the tube 20.
It is possible to overlap with the axial end portion of 7 or other shapes.

Fiber 10 as disclosed in co-pending US patent application (Sidra Specification CC-0078A) entitled "Fiber Grating Encased in Tube".
To accommodate the tube 20 with a laser, filament, flame, etc.
Can be heated, crushed, and fused to the diffraction grating 12. This patent application discloses this point. Other techniques can be used to collapse the tube 20 and fuse it to the fiber 10. Other methods include U.S. Pat. No. 5,745,626 entitled "Method for Housing Optical Fibers" applied to Duck et al. And / or "Integrated precision connection wells applied to Bakey. A method disclosed in U.S. Pat. No. 4,915,467 entitled "Method of Forming a Fiber Coupler Comprised". These are disclosed in this regard and may be referenced to understand the present invention or other techniques. As an alternative example, using a high temperature glass solder such as silica solder (powder or solid), the fiber 10,
The fiber 10 can also be fused to the tube 20, such as by fusion welding the tube 20 and such solder to each other, or by utilizing laser welding / fusion welding or other fusion welding techniques. It is also possible to fuse the fiber inside the tube, only a portion of the fiber inside the tube, or the fiber to the outer surface of the tube (described below with respect to FIG. 11).

As disclosed in co-pending US patent application (Sidra Specification CC-0078), the Bragg grating 12 is fusion spliced with a capillary 20 disposed around the fiber 10. Before or after this, it can be engraved inside the fiber 10. This patent application discloses this point. Co-pending U.S. patent application Ser. No. 09 / 205,845 entitled "Method and Apparatus for Forming a Bragg Grating Encased in a Tube" filed December 4, 1998 (Sidra Specification CC
No. 0130), when the tube 20 is placed around the diffraction grating 12 and then the diffraction grating 12 is engraved inside the fiber 10, the diffraction grating 12 is passed through the tube 20 by any desired technique. It can be drawn inside the fiber 10. This patent application discloses this point.

It is possible to house the diffraction grating 12 in the tube 20 with initial strain (compression or tension) applied by the tube, or to house them without initial strain. You can also For example, if Pyrex (registered trademark) or another glass having a coefficient of thermal expansion larger than that of the fiber 10 is used for the tube 20, when the tube 20 is heated to be fusion-welded to the fiber and then cooled, Tube 2
The diffraction grating 12 is compressed by 0. As an alternative embodiment, the fiber grating 12 can be housed in the tube 20 under tension by applying tension to the grating during the heating and fusion welding steps. Further, by housing the fiber diffraction grating 12 in the tube 20, neither tensile force nor compression force is applied to the diffraction grating 12 in a state where an external load is not applied to the tube 20.

As shown in FIG. 5, the shape of the capillary 20 can be changed depending on the application. For example, the shape of the tube 20 can be a "dogbone" shape having a narrow central portion 30 and an enlarged outer portion 32. The thin portion 30 has an outer diameter d2 of about 1 mm and a length L2 of about 5 mm. The enlarged portions 32 each have an outer diameter d3 of about 3 mm and a length L3 of about 4 mm. The lengths and outer diameters of these portions 30, 32 may be different. Such a dogbone shape can be utilized to increase the sensitivity in converting the load applied by the stepper motor 60 or actuator 154 into a wavelength shift of the diffraction grating 12 housed in the tube.

The inner transition region 33 of the enlarged portion 32 can be formed as a sharp vertical end or a beveled end, or it can be curved as shown by the dashed line 34. In the case of the curved shape 34, the stress applied to the rising portion is
Smaller than sharp edges, less likely to break. Further, part 3 of the tube 20
The end of 2 may be provided with an inner tapered section 22 or an outer flute section 27, as described above. Further, the portion 32 can be provided with an outer tapered (i.e. chamfered) corner 24 as described above.

Further, the dog bone shape does not need to be symmetrical. For example, if desired, the L3 of the two portions 32 can have different sizes. As an alternative embodiment, it is also possible that only one side is dogbone shaped. That is, instead of providing the two enlarged portions 32, the enlarged portion 32 can be provided only on one side portion of the thin portion 30 and the other side portion can be the linear end portion 37. The linear end portion 37 can be provided with the chamfered corner portion 24 as described above. In such a case, this dogbone shape becomes a shape in which a T-shape is laid sideways. In the present application, such a one-sided dogbone shape is also referred to as a "dogbone" shape.
Instead of the dogbone shape, other shapes can be used as long as they can improve strain sensitivity, adjust the force angle on the tube 20, or obtain other desired properties. It is also possible to use.

Since the diameter d3 of the enlarged portion 32 and the diameter d2 of the thin portion 30 are different as described above, the distortion is amplified, and thus the sensitivity of the wavelength shift of the diffraction grating to the load (
That is, it is known that the gain or the scale factor) increases. Furthermore, the dimensions of the dog bones described herein are easy to scale to obtain the desired sensitivity.

As shown in FIG. 6, as an alternative embodiment, axially along the fiber 10 to reduce strain on the fiber 10 at the interface between the fiber 10 and the tube 20. It is possible to provide an extended portion 36. Such a part 36
Are attached to the enlarged portion 32 at positions axially outside of the region to which the load is applied by the opposite end members 104 and 105. These are the end members 56, 50.
(FIG. 1), 74, 72 (FIG. 2), 159, 153 (FIG. 14), or piston 92 (FIG. 3). The axial length of the portion 36 can be larger or smaller depending on the application and design requirements. further,
Portions 36 need not be axially symmetric and, in addition, need not be provided at either axial end of tube 20. As mentioned above, it is also possible to provide the inner taper portion 22 or the outer flute portion 27 at the boundary between the fiber and the tube 20 in the portion 32. As an alternative embodiment, a portion of the portion 36 could be a stepped portion 39. In such a case, the region 22 can be provided within or near the stepped portion 39, as shown by the dashed line 38. Region 106 can be filled with air, adhesive, or filler. Furthermore, the pipe 20
Instead of having a dogbone shape, it is also possible to have a linear constant cross-sectional shape, as described above and shown by the dashed line 107. Further, as shown by the broken line 109, the end members 56, 50 (FIG. 1), 74, 72
(FIG. 2), 152, 150 (FIG. 14) or hole 1 through piston 92 (FIG. 3)
It is also possible to increase the diameter of 08 over its entire length or a part thereof. Co-pending US Patent Application No. (Sidra Specification CC-0078B
The capillaries 20 can also have another, axially extending shape, as described in US Pat. Further, it is also possible to construct the tube 20 of the present application with a plurality of concentric members, as described in the aforementioned co-pending US patent application. Further, the axially extending portion 36 can be part of the inner tube.

As an alternative embodiment, the tube 20 may be fusion spliced to the fiber 10 on both sides of the diffraction grating 12, as shown in FIG. In particular, the central portion 202 surrounding the diffraction grating 12 does not fuse to the fiber 10 but rather the region 200 of the tube 20 to the fiber 10. The area 202 around the diffraction grating 12 can be filled with the atmosphere, or this area can be in a vacuum state (or another pressure). It is also possible to fill some or all of it with an adhesive (eg epoxy), another filling material (eg polymer or silicone) or other material, or none. As mentioned above, the inner diameter d6 of the tube 20 is about 0.01 to 10 microns larger than the diameter of the optical fiber 10 (
For example, 125.01-135 microns). The inner diameter can be any other size, but the inner diameter d6 should be as close as possible to the outer diameter of the fiber 10 to prevent buckling of the fiber in such an embodiment. As an alternative embodiment, as described in the above-mentioned co-pending US patent application, two independent tubes are fusion welded on either side of the diffraction grating 12 and then the outer tube is fused over these tubes. Similar results can be obtained by touching.

It has been found that the present invention allows for high reproducibility, low creep, and low hysteresis (eg, about 3 picometers or less) depending on the configuration utilized. As shown in FIG. 8, in any of the embodiments described herein, instead of having only one diffraction grating housed in the tube 20, a plurality of diffraction gratings 220, 222 were contained in the tube 20. It can be embedded in the fiber 10. The reflection wavelengths and / or the reflection profiles of the diffraction gratings 220 and 222 may be the same or may be different from each other. Multiple diffraction gratings 150, 152 may also be utilized individually in the well-known Fabry-Perot configuration.

In addition, US Pat. No. 5,666,666 entitled “Compression Tunable Fiber Laser”.
One or more fiber lasers as disclosed in U.S. Pat. No. 372, which is disclosed in this regard and may be referred to in order to understand the present invention.
It can also be embedded in the fiber 10 inside 0. In such a case, the diffraction grating 22
0,222 to form an optical gap, at least for the optical fiber 10 between the diffraction gratings 220,222 (and optionally also for the diffraction gratings 220,222 and / or optical fibers outside the diffraction grating), a rare earth dopant. (For example,
Erbium and / or yttrium). Laser wavelength is tube 20
It is tuned according to changes in the load applied to.

Referring to FIG. 13, another type of tunable fiber laser that can be utilized is a tunable distributed feedback (DFB) fiber laser 234. Examples of such lasers include V.I. C. "DFB such as Lauridsen
Fiber Laser Design "(Electronic Letters, October 15, 1998, Vol. 34, No. 21, pp 2028-2030), P.P. "Erbium-doped fiber DFB laser with permanent π / 2 phase shift due to UV post-treatment", such as Birming, (IOOC'95, Tech Digest, Volume 5, PD1-3.
, 1995), US Pat. No. 5,771,251 named "optical fiber distributed feedback laser" assigned to Kringle Boton et al., US named "polarization fiber laser light source" assigned to Diamat et al. Examples include those disclosed in Japanese Patent No. 5,511,083. In such a case, the diffraction grating 12 is drawn inside the rare earth-doped fiber, and the predetermined position 2 near the center of the diffraction grating 12 is provided.
At 24, a phase shift of λ / 2 (λ is a laser wavelength) is generated. This, as is well known, provides a reliable resonant state that can be tuned continuously during longitudinal single mode operation without mode hopping. As an alternative embodiment, instead of providing only one diffraction grating, two diffraction gratings 220, 222 are placed close enough to form an air gap of length (N + 1/2) λ. You can also Here, N is an integer (including 0), and the diffraction gratings 220 and 222 are fibers doped with a rare earth element.

As an alternative embodiment, the DFB laser 234 can be placed in the fiber 10 between a pair of diffraction gratings 220, 222 (FIG. 8). In this case, at least a part between the diffraction gratings 220 and 222 is doped with a rare earth dopant. J
． J. It is described in "Interference-type fiber laser with low noise and controlled output" such as bread (E-Tech Dynamics, Sun Joe's, CA, Internet website www.e-tek.com/products/whitepapers) As described above, such a configuration is called an "Interactive Fiber Laser". If desired, one or more fiber laser configurations other than
It can also be placed in the fiber 10.

As shown in FIGS. 9 and 10, as an alternative embodiment, a plurality of fibers 10, 250 having at least one diffraction grating 12, 252 can be housed inside the tube 20. . The reflection wavelengths and / or the reflection profiles of the diffraction gratings 12 and 252 may be the same or may be different from each other. In such a case, the hole of the tube 20 is made large enough to receive both the fibers 10 and 250 before the heating and fusion welding of the tube 20. Further, the shape of this hole may be a shape other than a circle (for example, a square, a triangle, etc.). Also, the hole in tube 20 need not be centrally located along the centerline of tube 20.

Referring to FIG. 11, as an alternative embodiment, instead of contacting the fibers 10, 250 with each other as shown in FIG. 10, they may be separated by a predetermined distance within the tube 120. ing. The distance between the fibers 10,250 is
Within the outer diameter of tube 120, it can be of any desired size and can be oriented in any desired direction. Further, in any of the embodiments disclosed herein, it is possible, as noted above, to fuse some or all of the optical fiber and / or diffraction grating inside the tube, or some of these. Chisel 2
It is also possible to fuse the inside of the tube 0 or to the outer surface of the tube 20 (illustrated as fibers 500, 502 and 504, respectively).

As shown in FIG. 12, as an alternative embodiment, it is possible to fuse the tube 20 only to the portion of the fiber 10 where the diffraction grating 12 is present. In such an embodiment, if the tube 20 is longer than the diffraction grating 12, the inner tapered or flared portion 22 described above may be provided, and further, the region 28 between the tube 20 and the fiber 10 may be provided. The filling material as described above can be filled.
Furthermore, in this application, the term "tube" also means a block made of a material having the properties described in this application.

Further, in any of the embodiments described herein, instead of threading fiber 10 through housing 50, 70, 90 or tube 20, fiber 10 is provided with only one end, that is, fiber 10 It is also possible to project only one end of the housing or tube 120. In such a case, the fiber 10
One end of the fiber at the location where the fiber 10 exits the tube 20 or the housing 50, 70, 90, or at a portion prior thereto.

As shown in FIG. 17, as an alternative embodiment, replacing part or all of the fiber grating 20 housed in the tube with a large diameter silica waveguide grating 600. Is also possible. An example of such a waveguide grating is described in co-pending US patent application (Sidra Specification CC-0230) entitled "Optical Waveguide with Large Diameter, Diffraction Grating and Laser". There are things. This patent application discloses this point. Waveguide 6
00 has a core 612 (similar to the core of the optical fiber 10) and a cladding 614 (similar to the fusion welding of the tube 20 and the cladding of the fiber 10) to which the diffraction grating 12 is attached. It is embedded. Total length L1 of the waveguide 600
And the waveguide diameter d2 is the same as that described above for the tube 20 (
That is, buckling of tube 20 does not occur within the desired wavelength tuning range of the diffraction grating). The outer diameter of the waveguide is at least 0.3 mm. An optical fiber 622 (similar to fiber 10 of FIG. 1) having a cladding 626 and a core 625 for propagating the optical signal 14 is provided at one or both of the axial ends 6 of the waveguide 600.
28 or optically linked. This is done by known or yet to be developed techniques for coupling the fiber or coupling the light from the optical fiber into a large waveguide with acceptable optical losses for this application.

The waveguide having the diffraction grating 600 and having a large diameter can be used similarly to the diffraction grating 20 housed in the tube. In this case, the fiber 10 corresponds to (and can be replaced by) the core 612 of the waveguide 600. For example, the waveguide 600 may be etched, ground, or polished into the “dogbone” shape described above for the tube 20. As an alternative example, the two outer tubes 640, 642 can be heated and fused to the ends of the waveguide 600 to form a "dogbone" shape. All of the alternative embodiments described herein for tube 20 and tube-contained diffraction gratings are also applicable to waveguide 600. For example, a fiber laser or a DFB fiber laser can be configured, a plurality of fibers (or cores) can be arranged, or various shapes can be used.

In this application, both the tube-containing fiber grating 20 and the large diameter waveguide grating 600 are referred to as “tunable optical elements”. The tube housing type diffraction grating 20 and the waveguide type diffraction grating 600 having a large diameter have the same configuration and characteristics in a portion where the tube 20 is fusion-welded to the fiber 10. The tube-containing diffraction grating 20 and the waveguide diffraction grating 600 having a large diameter have a continuous cross section (that is, they are integrated), and a glass material (for example, doped) is provided over this cross section. This is because they are composed of substantially the same material such as silica and undoped silica). Moreover, in such parts, both of these have an optical core and a large cladding.

Furthermore, the waveguide 600 and the tube housing type diffraction grating 20 can be used together to configure the detection element of the embodiment described in the present application. In particular, one or more axial portions of the sensing element are diffraction gratings or fibers housed in a tube and / or one or more other axial portions are waveguides 600, the core of said waveguides being These may be axially bonded, fusion bonded, or otherwise mechanically or optically bonded so that they align with the core of the fiber that is fusion bonded to the tube. For example, as shown by the broken lines 650 and 652, it is possible to make the central region of the detection element a large waveguide and to make one or both of the axial ends be a tube housing type fiber, and to fuse them to each other. . Alternatively, the reverse is also possible.

Features, characteristics, modifications and improvements which have not been mentioned in the present application but which have been described in connection with the particular embodiment are applied to, utilized or introduced into the other embodiments described in the present application. It should be understood that it is possible. Moreover, the accompanying drawings are not shown to scale.

Although the present invention has been described and illustrated with respect to embodiments, the modifications and omissions described above and other modifications and omissions can be made without departing from the spirit and scope of the invention.

[Brief description of drawings]

[Figure 1]   FIG. 3 is a side view of a device for compressing the tube-enclosed fiber diffraction grating of the present invention.

[Fig. 2]   The side view of the other apparatus which compresses the tube accommodation type | mold fiber diffraction grating of this invention.

[Figure 3]   The side view of the other apparatus which compresses the tube accommodation type | mold fiber diffraction grating of this invention.

[Figure 4]   The side view of the tube accommodation type | formula fiber diffraction grating of this invention.

[Figure 5]   FIG. 5 is a side view of the tube-containing fiber diffraction grating of the present invention when the tube has another shape.

[Figure 6]   FIG. 5 is a side view of the tube-containing fiber diffraction grating of the present invention when the tube has another shape.

FIG. 7 is a side view of a tube-accommodating fiber diffraction grating in which tubes are fusion-welded to axial end portions on both sides of the diffraction grating region.

FIG. 8 is a side view showing a plurality of diffraction gratings provided on a fiber housed inside a tube according to the present invention.

FIG. 9 is a side view showing, according to the present invention, two fiber gratings provided on two separate optical fibers contained within a common tube.

[Figure 10]   FIG. 10 is an end view of the embodiment of FIG. 9 of the present invention.

FIG. 11 is a side view showing two fiber diffraction gratings provided on two separate optical fibers, housed within a common tube and spaced according to the present invention.

FIG. 12 is a side view of a tube containing fiber diffraction grating of the present invention in which the tube is fusion welded only to the longitudinal region of the fiber where the diffraction grating is present.

FIG. 13 is a side view of a tunable distributed feedback (DFB) fiber laser housed in a tube of the present invention.

FIG. 14 is a side view of an apparatus of the present invention for compressing a tube-containing fiber grating using an actuator to tune the grating.

FIG. 15 is a side view of an apparatus of the present invention for compressing a tube-containing fiber grating using a precision pressure source to tune the grating.

FIG. 16 is a side view of an apparatus of the present invention for compressing a tube-containing fiber grating using a precision pressure source to tune the grating.

FIG. 17   The side view which shows what has a diffraction grating inside the optical waveguide of large diameter.

─────────────────────────────────────────────────── ─── Continued front page    (31) Priority claim number 09/589974 (32) Priority date December 6, 1999 (December 1999) (33) Priority claiming countries United States (US) (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, SD, SL, SZ, TZ, UG, ZW ), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, C U, CZ, DE, DK, EE, ES, FI, GB, GD , GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, L K, LR, LS, LT, LU, LV, MD, MG, MK , MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, T M, TR, TT, UA, UG, UZ, VN, YU, ZA , ZW (72) Inventor Miller, Matthew Bee.             Glasto, Connecticut, United States             Merry, Deerfield Drive             140 (72) Inventor Sullivan, James M.             United States, Connecticut, Manchester             Star, Backland Hills Drive               465 (72) Inventor Davis, Michael A ..             Glasto, Connecticut, United States             Merry, Stevens Lane 172 (72) Inventor Burkato, Robert N.             United States, Connecticut, Water             Berries, Scott Road 268-1 (72) Inventor Kelsey, Arandy.             United States, Connecticut, South             Glastonbury, Taylor Townro             Code 75 (72) Inventor Putnan, Martin A.             Cheshire, Connecticut, United States             ー, Lancaster Way 78 (72) Inventor Sanders, Paul Yi.             Madison, Connecticut, United States             Center Village Drive 1 F-term (reference) 2H038 AA08 AA21 AA51 BA23 BA24                 2H041 AA21 AB10 AC01 AZ02 AZ05                       AZ08                 2H049 AA45 AA50 AA59 AA62 AA66                       AA68                 5F072 AB07 AK06 HH05 KK07 MM18                       PP07 [Continued summary] It is also possible to construct a tunable DFB laser. It In addition, if the element (20) has an inner tapered region (22) Providing a tapered (flute) portion (27) Is also possible. For compression, PZT, stepper motor, if Or using other actuators or fluid pressure You can

Claims (37)

[Claims] 1. A compression tunable optical fiber device comprising a tunable optical element having an outer diameter of at least 0.3 mm and at least one reflective element disposed along its longitudinal axis. A compression tunable optical fiber device, wherein at least a part of the tunable optical element has a continuous cross section and is made of substantially the same material. 2. An optical fiber having the reflective element embedded therein, and a tube accommodating the optical fiber and the reflective element along a longitudinal axis thereof, the tube comprising: The compression-tuned optical fiber device according to claim 1, wherein the compression-tunable optical fiber device is fused to at least a part of the fiber. 3. The compression tunable optical fiber of claim 1, wherein the tunable element comprises a large diameter optical waveguide having an outer cladding and an inner core therein. apparatus. 4. A large diameter light guide in which the tunable element comprises a tube fused to at least a portion of an optical fiber along a longitudinal axis, an outer cladding and an inner core provided therein. 2. The compression tunable optical fiber device according to claim 1, further comprising a waveguide, wherein the tube and the waveguide are fusion-welded to each other in the axial direction and are optically coupled to each other. 5. The compression tunable light of claim 4, wherein the reflective element is housed inside the fiber and is housed in the tube along a longitudinal axis of the tube. Fiber equipment. 6. The compression-tuned optical fiber device according to claim 4, wherein the reflection element is arranged inside the optical waveguide. 7. The compression-tuned optical fiber device according to claim 1, wherein the material is a glass material. 8. The compression-tuned optical fiber device according to claim 1, wherein the tube is fusion-welded to a region of the optical fiber where the reflective element is present. 9. The compression-tuned optical fiber device according to claim 2, wherein the tube is fusion-welded to the optical fiber on both sides in the axial direction of the reflecting element. 10. The compression tuned optical fiber device of claim 2, wherein the device further comprises a plurality of the optical fibers housed within the tube. 11. The compression tuned fiber optic device of claim 3, wherein the device further comprises a plurality of the cores disposed within the waveguide. 12. The compression tunable optical fiber device according to claim 1, wherein the tunable element internally includes a plurality of reflective elements. 13. The tunable element internally comprises at least a pair of reflective elements, wherein at least a portion of the tunable element between the pair of elements is doped with a rare earth dopant. 2. The compression tuned optical fiber device according to claim 1, wherein the laser comprises a laser. 14. The compression tunable fiber optic device of claim 13, wherein the laser produces a laser with a laser wavelength that varies with changes in the load on the tunable element. 15. The tunable device according to claim 1, wherein at least a region in which the reflective element is present is doped with a rare earth dopant, and the reflective element constitutes a DFB laser. A compression-tuned optical fiber device as described. 16. The DFB laser produces a laser with a laser wavelength that varies with changes in the load applied to the tunable element.
3. The compression-tuned optical fiber device according to item 3. 17. The compression tuned fiber optic device of claim 1, wherein the material is silica. 18. The compression tuneable fiber optic device of claim 1, wherein at least a portion of the tunable element is cylindrical. 19. The compression tuneable fiber optic device of claim 1, wherein the tunable element comprises at least one tapered axial portion. 20. The reflective element has a characteristic wavelength such that the tunable element has a predetermined sensitivity of the characteristic wavelength shift to changes in load applied to the tunable element. The compression-tuned optical fiber device according to claim 1, which has a shape as described above. 21. The compression tunable optical fiber device according to claim 1, wherein the tunable element has a dogbone shape. 22. A method for tuning the wavelength of a fiber optic device, comprising: a) an outer diameter of at least 0.3 mm and at least one reflective element disposed along its longitudinal axis; Providing a tunable optical element, the cross-section of which is continuous in part and consisting essentially of one continuous material, b) compressing the tunable element axially, A method comprising changing a reflection wavelength of the reflection element. 23. The element comprises a tube containing an optical fiber and the reflective element along its longitudinal axis and fused to at least a portion of the fiber. 23. The method of claim 22. 24. A method, wherein a plurality of said optical fibers are contained inside said tube. 25. The method of claim 22, wherein the tunable element comprises a large diameter optical waveguide having an outer cladding and an inner core therein. 26. The method of claim 22, wherein the waveguide comprises a plurality of the cores. 27. The method of claim 22, wherein the tunable element internally comprises a plurality of reflective elements. 28. The tunable element internally comprises at least one pair of reflective elements, wherein at least a portion of the tunable element between the pair of elements is doped with a rare earth dopant. 23. The method of claim 22, wherein the laser is configured. 29. The method of claim 28, wherein the laser produces a laser with a laser wavelength that varies with changes in the load on the tunable element. 30. In the tunable device, at least a region in which the reflective element is present is doped with a rare earth dopant, and the reflective element constitutes a DFB laser. The method described. 31. The DFB laser produces a laser with a laser wavelength that varies with changes in the load applied to the tunable element.
0. A compression-tuned optical fiber device according to item 0. 32. The reflective element has a characteristic wavelength, and the tunable element has a predetermined sensitivity of the characteristic wavelength shift to changes in load applied to the tunable element. 23. The method of claim 22, having a shape such as: 33. The method of claim 32, wherein the tunable element has a dogbone shape. 34. The method of claim 22, wherein the compressing step compresses the tunable element with an actuator. 35. The method of claim 34, wherein the actuator is a stepper motor, piezo electric actuator, solenoid, or pneumatic actuator. 36. The method of claim 22, wherein the compressing step compresses the tunable element by fluid pressure. 37. The material of claim 22, wherein the material is a glass material.
The method described.