CN2569169Y - Optical fibre collimator - Google Patents

Abstract

An optical fiber collimator, mainly composed of an outer tube, a lens and an optical fiber head, is characterized in that the lens is an aspherical lens, the outer diameter of which is designed to be the same as the inner diameter of the outer tube, and is inserted into the outer tube to interfere with the The second end face of the gasket provided in it is fixed; the outer sleeve tube is provided with a gasket, and the thickness of the gasket is designed to be equal to or greater than the effective focal length of the aspheric lens in consideration of machining tolerances; the optical fiber head, its The outer diameter is the same as the inner diameter of the outer sleeve, and it is inserted into the outer sleeve and fixed against the first end face of the gasket; the defocus distance Δd of the end point of the optical fiber can be controlled within 30μm≥Δd≥0, and the optimal working distance is controlled at Various specifications in the range of 0mm to 140mm, and keep the insertion loss below 0.15dB. The actual assembly process does not require optical adjustment procedures, which greatly reduces production costs and improves optical performance. It can be applied to components with long working distances to increase The scope of application is practical.

Description

Fiber Collimator

technical field

The utility model relates to an optical fiber collimator, in particular to an optical fiber collimator which improves optical performance and can be applied to long working distance components.

Background technique

In optical communication components, it is often necessary to expand and parallelize the beam transmitted in the optical fiber, pass through some functional components, and then focus the parallelized beam and couple it back into the optical fiber for further transmission. The part that plays this role is the fiber collimator (Fiber Collimator); and the fiber collimator system includes two fiber collimators in pairs, one fiber collimator can make the outgoing beam with a certain divergence angle (NA) , after the beam is parallelized by the collimating lens, after passing through the working distance of the system, another fiber collimator will focus the beam and couple it back into the optical fiber, and the working distance is for placing various functional parts; and an optical fiber The optimal working distance range of the collimator system is the distance between the two fiber collimators when the parallel light beam between the two fiber collimators can maintain parallelism and maintain the lowest insertion loss (Insertion Loss) of the system.

The structure or manufacturing technology of known fiber collimator (Fiber Collimator) again, as shown in Figure 1, this fiber collimator 10 is to utilize a glass sleeve (Glass Tube) 11 with smooth inner diameter, in the sleeve pipe 11 Fix a fiber head 12 (or pin) with the same outer diameter (Outer Diameter, O.D.) as the sleeve inner diameter (Inner Diameter, I.D.) to position the fiber 13, and a graded-index (GRIN) The lens (or called GRIN-tyPelens) 14 is used to parallelize the light beam of the optical fiber 13 or couple the parallelized light beam back into another optical fiber, and coat a stainless steel sleeve 15 outside the glass sleeve 11 as a follow-up For welding engineering, including laser welding (Laser Welding) and soldering (Soldering) and so on. When assembling the fiber collimator, in order to reduce the insertion loss (Insertion Loss) of the collimator, it is usually necessary to adjust the relative position of the fiber head 12 and the gradient index lens 14 in real time, so that the output beam is within the working distance (Working Distance) Within the range, the best parallel beam, that is, the minimum beam divergence (Beam Divergence) and the minimum deflection angle. However, the above-mentioned optical fiber collimator 10 with graded-index (GRIN) lens 14 or its manufacturing method includes: No. 494250 "Optical Fiber Collimator and Its Manufacturing Method" published on July 11, 2002 Patent (Application No. 090128544), and the creation patent of US6,168,319B1 "SYSTEM AND METHOD FOR ALIGNING OPTICAL FIBERCOLLIMATORS" announced on January 2, 2001, have the following disadvantages in the process and use:

(1) The manufacturing technology of the cylindrical graded-index (GRIN) lens itself is highly difficult, and cannot be formed easily, which relatively increases the manufacturing cost.

(2) Once the length of each GRIN lens is selected, the working distance of the fiber collimator system is also fixed. Therefore, the working distance is determined first according to the needs of the functional parts in manufacturing, and the GRIN lens is determined The length of the required GRIN lens has various length specifications, which increases the production trouble.

(3) When assembling a GRIN-type fiber collimator, in order to reduce the insertion loss of the collimator, it is usually necessary to adjust the relative position of the fiber head and the gradient index lens in real time so that the output beam is within the working distance (Working Distance) can achieve the best parallel light beam, but each optical adjustment operation involves the alignment adjustment of the five-axis degrees of freedom of X, Y, Z, θ, φ, the process is quite complicated, and the relative improvement of production cost.

(4) For functional parts with a long working distance, the GRIN-type fiber collimator cannot keep the insertion loss (Insertion Loss) below 0.15dB, resulting in reduced optical performance, and is not suitable for long working distances such as long Components up to 100mm to 140mm, such as optical circulators (Optical Circulator), optical interleaver (Optical Interleaver), optical switches (Optical Switch) and other multi-port optical components (Multi-port Optical Device), and the use quality cannot Meet the requirements.

In view of this, the inventor finally has the utility model to produce through in-depth research and development.

Contents of the invention

The utility model provides an optical fiber collimator to solve the technical problem that it can be applied to components with a long working distance to increase the application range and improve the optical performance.

The technical solution adopted to solve the above-mentioned technical problems is as follows:

An optical fiber collimator, mainly composed of an outer sleeve, a lens and an optical fiber head, is characterized in that:

The lens is an aspherical lens whose outer diameter is designed to be the same as the inner diameter of the outer sleeve, and is inserted into the outer sleeve to be fixed against the second end surface of the washer provided therein;

The outer sleeve is provided with a gasket in the tube, and the thickness of the gasket is designed to be equal to or greater than the effective focal length of the aspheric lens in consideration of machining tolerances;

The optical fiber head, whose outer diameter is the same as the inner diameter of the outer sleeve, is inserted into the outer sleeve and fixed against the first end surface of the gasket, and its effective focal length can be detected by the wavelength of light;

With the above-mentioned structure, the fiber collimator completed by each group, because the thickness of the gasket varies with the tolerance of machining, the defocus distance of the fiber end point is controlled within a certain range, and the best work of each fiber collimator is achieved. The distance is controlled within a large range to simplify the manufacturing process of the fiber collimator;

The aspheric lens may be a nearly zero-aberration molded aspheric glass lens;

The outer casing is made of stainless steel;

The gasket is integrally formed with the outer casing;

The outer casing is made of glass;

The optical fiber head and the aspherical lens are respectively fixed on the first end surface and the second end surface on both sides of the gasket with UV glue;

The outer casing is provided with a vent hole in the length of the gasket to keep the internal air pressure the same as that of the outside to improve the reliability of environmental factors;

The part where the thickness of the gasket is greater than the effective focal length of the aspheric lens is preferably no more than 30 μm;

The machining error is generally within the range of 5-15 μm, and the thickness T of the gasket is designed as T=(f+15 μm)±15 μm, where f is the effective focal length of the aspheric lens;

The defocus distance Δd of the fiber end point is controlled and randomly falls within the range of 30μm≥Δd≥0;

The optimal working distance of the fiber collimator is controlled and randomly falls within the range of 0mm to 140mm, and the insertion loss is kept below 0.15dB.

The utility model is mainly composed of an outer sleeve provided with a gasket, an aspheric lens and an optical fiber head, and the inner diameter of the outer sleeve is the same as the outer diameter of the optical fiber head of an optical fiber and the outer diameter of the aspheric lens, so that The optical fiber head and the aspherical lens can be inserted from both ends of the outer sleeve respectively, and they are respectively opposed to the end faces of the gasket on both sides and fixed, and the thickness of the gasket in the outer sleeve is designed to be equal to or greater than the aspheric lens in consideration of machining tolerances The effective focal length (Effective Focal Length, EFL), and make the larger part not more than 30 μm is the best, then the above structure can simplify the assembly process of the fiber collimator without complicated known optical adjustment program, to greatly reduce the production cost, and the defocus distance Δd of the fiber end point is set to randomly fall within the range of 30μmΔd0, so that the optimal working distance of the fiber collimator after each setting is also random and inclusive Various specifications in the range of 0mm ~ 140mm, thus solving the technical problem of making it applicable to components with long working distance and increasing the application range to improve optical performance.

The utility model has a simple structure, and is composed of an outer sleeve provided with a gasket and an aspheric lens and an optical fiber head, and the aspheric lens and the optical fiber head can be inserted into the outer sleeve and pressed tightly to be fixed on the gasket. Both sides of the end face, and considering machining tolerances, make the thickness of the gasket equal to or greater than the effective focal length of the aspheric lens, and make the larger part not more than 30 μm, which can avoid known optical adjustments during assembly The manufacturing process is troublesome, and the optimal working distance of each finished product can randomly cover various specifications in a large range from 0mm to 140mm, so it is practical. Its advantages are as follows:

(1) The utility model does not need cumbersome alignment procedures when assembling, and the optimal working distance is slightly changed by considering the error of mechanical processing. It is only necessary to test the optical properties of the finished product after the passive assembly (Passive Alignment) procedure is completed. , including insertion loss, reflection loss, and optimal working distance.

(2), in order to achieve the best optical characteristics at different working distances, including the smallest scattering angle, the lowest insertion loss, the smallest deflection angle and the lowest reflected light, etc., in the known use of gradient index lenses Technology usually requires real-time adjustment of the relative position of the fiber optic head and the gradient index lens; while using an aspheric glass lens, due to the error in the relative position of the fiber optic head and the aspheric lens, the optimum working distance is changed instead of Uncompensated increase in insertion loss.

(3) The utility model utilizes the characteristics of mechanical processing and can produce collimators with different working distances without real-time adjustment.

Description of drawings

Fig. 1 is a cross-sectional view of a known fiber collimator.

FIG. 2 is a schematic diagram of the optical characteristics of an aspheric lens.

Fig. 3 is an exploded sectional view of the fiber collimator of the present invention.

Fig. 4 is a combined sectional view of the fiber collimator of the present invention.

Detailed ways

As shown in Figure 2, it is the optical characteristic of an aspheric lens, to illustrate the technical principle of the utility model structure, this aspheric lens 20 is an optimization, minimum aberration, and effective focal length is the aspheric lens of f; When the Gaussian beam (Beam Waist=ω ₁ ) emitted from the fiber tip (Fiber Tip) is focused on d ₂ after passing through the length d ₁ (d ₁ is the distance from the fiber tip to the aspheric lens) and the aspheric lens 20, And 2d ₂ is the optimal working distance of the fiber collimator system at this time, the waist width (beamwast) is the spot radius (spot radus) becomes ω ₂ ; The calculation formula of the relationship between ω ₂ and ω ₁ , f, Δd (Δd=d ₁ -f), etc. can be obtained. It can be known from the above optical characteristics that when an aspheric lens is used in the fiber collimator, the relative distance between the end point of the fiber and the focal length f of the lens can be changed, that is, the defocus distance Δd of the end point of the fiber (Δd=d ₁ -f), to Analyze various focusing conditions after passing through the lens, and divide them into Δd=0 when d ₁ =f, Δd>0 when d ₁ >f, Δd>>0 when d ₁ >>f, and Δd>>0 when d ₁ <f Δd<0 and other different conditions, explain the results respectively:

Example (1): When d ₁ = f, Δd = 0, at this time the focal point is at a distance from the lens f, parallel light has the largest spot radius or spot size and the smallest scattering angle, The best working distance is 2f;

Example (2): When d ₁ > f, Δd > 0, that is, the end point of the fiber moves away to the left in the figure, and at this time the focal point is gradually moving away from the lens f, that is, the optimal working distance is getting larger and larger. At this time, there is Gradually smaller spot size and larger scattering angle;

Example (3): When d ₁ ＞＞f, Δd＞＞0, that is, the end point of the fiber moves to the left in the figure beyond a certain distance. At this time, the focal point is smaller than the lens f, and there is a small spot size ( spot size) and large scattering angle;

Example (4): When d ₁ <f, Δd<0, that is, the end point of the fiber moves to the right and approaches the aspheric lens. At this time, the parallel light diverges directly without focusing, and its virtual focal point is in front of the aspheric lens 20 (that is, d ₂ <0), and there is no optimal working distance.

According to the above, substituting the optical characteristics of single-mode fiber, it is further known that when the defocus distance Δd (Δd=d ₁ -f) of the fiber end is in the range of 5-60 μm, the The best working distance achieved can be from 0mm to 150mm, and at this time the scattering angle is less than 0.0025° and the insertion loss of the collimator system comes from the misalignment of the Gaussian beam emitted by the two collimators and the size of the spot Unmatched spot-size; therefore, in the above cases (1) to (3), it can be assumed that the aperture size of the lens (Aperature) is much larger than the spot size of the incident Gaussian beam, as long as the two collimators work When the distance is adjusted to the optimal working distance (ie 2d ₂ ), the insertion loss of the collimator due to the inconsistency of the spot size can approach zero.

As shown in Figures 3 and 4, the utility model is designed based on the above-mentioned optical characteristics when an aspheric lens is used in a fiber collimator, especially when the defocus distance (Δd) of the fiber end point can be effectively controlled, that is The optimum working distance (2d ₂ ) of the fiber collimator system can be controlled.

The structure of the optical fiber collimator of the present utility model is mainly composed of an outer sleeve (Holder) 30 and an aspherical lens (Aspherical Lens) 40, and a gasket (Spacer) 31 is provided in the inner diameter of the outer sleeve 30, and considering Machining tolerances, the thickness T of the gasket 31 is designed to be equal to or greater than the effective focal length f (Effective Focal Length, EFL) of the aspheric lens 40, and wherein the larger part is preferably no more than 30 μm; The outer diameter of the optical fiber head 51 of 50 is the same as the inner diameter of the outer sleeve 30, and can be inserted into the outer sleeve 30 and fixed against the first end face 32 of the gasket 31; and the outer diameter of the aspheric lens 40 is the same as the outer diameter of the outer sleeve 30 have the same inner diameter, they can be inserted into the outer sleeve 30 and fixed against the second end surface 33 of the gasket 31; then the above-mentioned fiber collimator structure, because the thickness T of the gasket is different due to the machining tolerance, the fiber end point 52 The defocus distance Δd (Δd=d ₁ -f, d ₁ is the distance from the fiber end point 52 to the aspheric lens 40) is controlled within the range of 30 μm Δd0, and thus the optimal working distance (Working Distance) of each fiber collimator ) can be controlled within the range of 0mm ~ 140mm, so the working distance of each fiber collimator can be detected one by one by optical instruments. When used for production control, the completed fiber collimators can be different according to the working distance, such as from From 0mm to 140mm, each 20mm is divided into multiple grades, which are screened and graded, so that various components with different working distances can be easily selected.

Because the thickness T of the gasket 31 is controlled to be equal to or greater than the effective focal length (EFL) f of the aspheric lens 40, and the greater part is not more than 30 μm as the best design principle, the considered machining error is generally It is in the range of 5-15 μm, so the thickness T of the gasket 31 can be designed as T=(f+15 μm)±15 μm.

In addition, the aspherical lens (Aspherical Lens) 40 can be a nearly zero-aberration molded aspheric glass lens (Molding Aspherical Glass Lens), that is, after its aberration is corrected by the aspheric surface high-order coefficient (High-Order Coefficient) It has approached zero (<0.025λatλ=0.6328μm); and the outer sleeve 30 can be made of stainless steel or glass material, and the gasket 31 can be integrally formed with the outer sleeve 30; the optical fiber head 51 and the aspheric lens 40 can be The first end surface 32 and the second end surface 33 on both sides of the washer 31 are respectively fixed with UV glue. And the length of gasket 31 is provided with a vent hole 34 of appropriate size, to keep its internal air pressure the same as the outside, to improve the reliability of environmental factors.

Since the working distance of the optical fiber collimator system of the utility model can be effectively controlled by the thickness T of the washer, the required working distance specification can cover a large range from 0mm to 140mm, and the insertion loss can be kept below 0.15dB; In addition, the utility model does not need an optical adjustment program in the actual assembly process, and only needs to use the optical beam profile (Optical Beam Profile) at the back stage to classify and screen different working distances caused by machining tolerances; therefore, the structure of the utility model The design can greatly reduce the production cost, avoid the time-consuming and laborious optical adjustment of the known technology, and improve the optical performance, and can be applied to components with long working distance, such as optical circulator (Optical Circulator), optical interleaver (Optical Interleaver) ), optical switch (Optical Switch) and other multi-port optical components (Multi-port Optical Device).

The above is only an embodiment of the present utility model, and is not intended to limit the implementation scope of the present utility model. Generally, those who are familiar with the art can make other equivalent changes or changes according to the characteristic category of the present utility model. Modifications should all be covered within the patent scope of the utility model application.

To sum up, the utility model can indeed achieve the expected effect by the structure disclosed above, and the utility model has not been seen in publications or used publicly before the application, and has met the requirements of novelty and advancement of utility model patents. Therefore, a utility model patent application is filed in accordance with the law.

Claims (11)

1. An optical fiber collimator, mainly composed of an outer sleeve, a lens and an optical fiber head, is characterized in that: The lens is an aspherical lens whose outer diameter is designed to be the same as the inner diameter of the outer sleeve, and is inserted into the outer sleeve to be fixed against the second end surface of the washer provided therein; The outer sleeve is provided with a gasket in the tube, and the thickness of the gasket is designed to be equal to or greater than the effective focal length of the aspheric lens in consideration of machining tolerances; The outer diameter of the optical fiber head is the same as the inner diameter of the outer sleeve, and is inserted into the outer sleeve and fixed against the first end surface of the washer. 2. The optical fiber collimator according to claim 1, wherein the aspherical lens is a nearly zero-aberration molded aspheric glass lens. 3. The fiber collimator according to claim 1, characterized in that: the outer sleeve is made of stainless steel. 4. The optical fiber collimator according to claim 1, characterized in that: the gasket and the outer sleeve are integrally formed. 5. The fiber collimator according to claim 1, wherein the outer sleeve is made of glass. 6. The optical fiber collimator according to claim 1, characterized in that: the optical fiber head and the aspheric lens are respectively fixed on the first end surface and the second end surface on both sides of the washer with UV glue. 7. The fiber collimator according to claim 1, characterized in that: the outer sleeve is provided with a vent hole in the length of the gasket to keep the internal air pressure the same as the external one. 8. The fiber collimator according to claim 1, characterized in that: the thickness of the spacer is preferably no more than 30 μm for the portion greater than the effective focal length of the aspheric lens. 9. The optical fiber collimator according to claim 1 or 8, characterized in that: its machining error is generally within the range of 5-15 μm, and the thickness T of the gasket is designed as T=(f+15 μm)±15 μm, the formula Middle f is the effective focal length of the aspheric lens. 10. The optical fiber collimator according to claim 1 or 9, characterized in that: the defocus distance Δd of the end point of the optical fiber is controlled and randomly falls within the range of 30 μm≥Δd≥0. 11. The fiber collimator according to claim 1 or 10, characterized in that: the optimal working distance of the fiber collimator is controlled and randomly falls within the range of 0 mm to 140 mm, and the insertion loss is kept below 0.15 dB.

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