TW200428050A - Free space grating wavelength division multiplexer - Google Patents

Abstract

A free space grating wavelength division multiplexer at least comprises a grating, a focusing lens, and an array of microlens. The present invention can process light beams with different wavelength respectively by using the array of microlens, and the focus points of the light beams with different wavelength can be arranged in the same plane. The advantages of the present invention includes that photo efficiency can be increased, intensities of light beams can be adjusted respectively, channel bandwidth can be increased and/or adjusted, channels can be cut off respectively, and…etc.

Description

200428050 V. Description of the invention (1). The technical field to which the invention belongs-The present invention relates to a wavelength multiplexer (Wavelel ^ gth

Division Mul tipi ex er (referred to as WDM), and especially 疋 5 on a kind of :: ancient long multiplexer. FreeSpace Grating / In contrast to the previous technology, in the early optical fiber communication applications, there is only one communication channel for an optical fiber. There are two main ways to increase the bandwidth without consuming a new optical fiber network. The first is to increase the operating frequency of the circuit system, which is limited to the high price of high-frequency circuits. The other method is to transmit many messages carried by different wavelengths on the same day f. In this method, as long as it transmits ~ 4 or 16 2 × 5 G Η ζ bandwidth messages of different wavelengths at the same time, all the total Bandwidth ^ can reach 10 GHz or 40 GHz. This method has lower cost and lower technical obstacles, but the system has better stability and the system has expandability. This method separates and combines light with different wavelengths. The technology is the wavelength multiplexing (WD M) technology. There are four major categories of density and wavelength multiplexing technologies: thin film filters (TFF), and fiber waveguides (ArraY Wave).

Gyide (AWG for short), Fiber Bragg Gratting (FBG), and free space grating. The principle of thin film filters and optical plates is to use a coating method. The required film layer is plated on thin flat glass layer by layer based on the principle of vapor deposition. When light passes through different types of filters ^, different wavelengths are filtered separately. Out, to achieve the effect and effect of partial wave. f: Thin film filters are difficult to make due to the increase in the number of film layers when the number of channels is increased. Therefore, thin film filters are often used for 6 channels.

200428050 V. Description of the invention (2) High-density wavelength multiplexing technology below. The principle of the fiber waveguide is to use the difference in the optical path length of each wavelength in the waveguide to achieve the effect of demultiplexing. The disadvantage of this technology is that the waveguide is susceptible to environmental effects such as temperature, so it needs good insulation before a large number of commercialization Packaging. This is also the most difficult technical obstacle to fiber waveguides. Fiber Bragg Grating irradiates the fiber with ultraviolet rays, so that part of the material in the fiber filament is changed into an approximate Bragg diffraction grating. The characteristics of optical diffraction are used to separate out waves of different wavelengths, but because the fiber grating itself is an optical fiber, so It is not conducive to making multi-channel wavelength multiplexing technology. The above three technically face different difficulties, while the free space grating uses the principle of wavelength division of the traditional spectrometer, and uses the grating to diffract different wavelengths Φ to different positions to achieve the effect of wavelength division, as shown in Figure 3. Or as shown in Figure 4. Figure 3 is a schematic diagram of a conventional free-space grating wavelength multiplexing technology structure, including a light source fiber 3 2, a lens 3 4, a reflective grating 36, and a plurality of receiving fibers 38. After the incident light beams having different wavelengths are emitted from the light source fiber 3 2, they pass through the lens 34 to the reflective grating 36, and reflect and split the light beams of different wavelengths, and are then focused and coupled to the receiving fibers 38 by the lens 34. Figure 4 is a schematic diagram of another free-space grating wavelength multiplexing technology, which includes a light source fiber 3 2, a concave mirror grating 4 6, and a plurality of receiving fibers 3 8. When the incident light beams with different wavelengths are emitted from the light source fiber 32, they reach the concave mirror grating 46, and the light beams with different wavelengths are reflected and split, and are focused and coupled to the receiving fiber 38. In the above two optical path structures, the focal points of different wavelength beams after reflection and splitting are mostly curved, but the receiving fibers 38

10732twf.ptd Page 11 200428050 V. Description of the invention (3) It is flat, so that it is not possible to effectively combine all the different wavelength beams to the. Fiber at the same time, which reduces the optical efficiency. SUMMARY OF THE INVENTION Accordingly, the present invention provides a free-space grating wavelength multiplexer, which can focus the focal points of beams of different wavelengths on the same plane to increase the optical efficiency. In addition, the beams of different wavelengths can be processed separately. , Such as adjusting the intensity or increasing the channel bandwidth, or even closing individual channels. The present invention proposes a free-space grating wavelength multiplexer, which at least includes: a grating, a focusing lens, and a micro-optical element array. The above grating diffracts the first beam to obtain a plurality of second beams of different wavelengths, and the focusing lens focuses these second beams to obtain a plurality of third beams. Φ The micro-optical element array includes a plurality of micro-optical elements, and each of these micro-optical elements processes the third light beams separately to obtain a plurality of fourth light beams. According to a preferred embodiment of the present invention, the fourth light beams in the free-space grating wavelength multiplexer are coupled to a plurality of light receiving devices, such as optical fibers. And the micro-optical element array can make the focal points of the fourth light beams align on the same plane, or the micro-optical element array can individually adjust the intensity of the fourth light beams received by the light receiving devices, or even the micro-optics The element array can adjust the channel bandwidth and the like of the fourth light beam respectively received by the light receiving devices. The above micro-optical elements can be multiple micro-focusing lenses with different focal lengths, or multiple Fresnel lenses, or even multiple diffractive optical elements. According to the free space grating wavelength multiplexer according to the preferred embodiment of the present invention, the main material of these micro-optical elements can be electrochromic

10.732t.wf. These micro-optical elements can also be a plurality of light-emphasis devices, which can individually control the intensity ratio of the fourth light beam to the corresponding third light beam, or can individually control whether one of these third light beams is passed or turned off. The free-space grating wavelength multiplexer according to a preferred embodiment of the present invention, wherein the micro-optical element array further includes a silicon wafer holder, which has at least one opening as a light beam channel, and these The micro-optical element is disposed in the opening of the silicon wafer holder. The present invention further proposes a free-space grating wavelength multiplexer, which is different from the foregoing in that the micro-optical element array is made of a single micro-optical element, and the main point is that these third beams can be processed separately. To obtain a plurality of fourth beams. For example, the micro-optical element may be an active Frean micro lens (F r e s n e 1 1 e n s) array, which is mainly composed of a single diffractive optical element with different focal lengths. In the embodiment, the micro-optical element includes a silicon wafer holder, a liquid crystal layer, a substrate, and a conductive layer. The silicon wafer holder has at least one opening as a channel for the light beam. A substrate made of a light-transmissive film material is used to sandwich the liquid crystal layer. The conductive layer includes an electrode having a pattern defined therein. The pattern is disposed in an opening of a silicon wafer holder. The characteristics of light transmission through the liquid crystal layer can be controlled by controlling the voltage applied to the electrode. For example, the shape of this pattern is a Fresnel board (F resne 1 ζ ο ne ρ 1 ate), which can control the focus or Out of Focus.

10732twf.ptd Page 13 200428050 V. Description of the invention (5) Because the present invention uses a micro-optical element array or its equivalent, it can ... process the light beams of different wavelengths separately, so that the light beams of different wavelengths can be processed. Focus points are arranged on the same plane to increase optical efficiency. In addition, the beam intensity can be adjusted individually, the function of the equalizer (Equalizer) can be increased, or the channel bandwidth can be increased, or even individual channels can be closed. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below in conjunction with the accompanying drawings for detailed and detailed descriptions as follows: Implementation ♦ Please refer to Section FIG. 1 is a schematic structural diagram of a free-space grating wavelength multiplexer according to a preferred embodiment of the present invention. This preferred embodiment Φ The proposed free-space optical interpolation wavelength multiplexer includes: a light source fiber 1 2, a first micro-optical element array 10, a second micro-optical element array 1 5, a focusing lens 14, and a reflective grating 1 6 and 2 receiving fibers 1 8. If you are familiar with this art, you can easily know that the two receiving optical fibers 18 are just examples, but in fact, they can be any number of optical receiving devices. In the same way, the optical fiber 12 is not limited. It must be an optical fiber, and other devices that can transmit light can be used. In this embodiment, the light source optical fiber 12 emits light or laser light that is mixed with many different wavelengths (the mixed wavelength is represented by ί), that is, emits light beams carrying signals of different channels. When this light beam reaches the reflective grating 1 Before 6 o’clock, it is called the first light beam, and the reflective grating 16 diffracts the first light beam and reflects to obtain a plurality of second light beams of different wavelengths. Here are two light beams of different wavelengths (respectively Expressed as λ 1 and λ 2). As those skilled in the art can easily know, this embodiment uses the reflective grating 16 but it is not limited.

10732t.wf.ptd Page 14 200428050 V. Description of the invention (6) It must be reflective, as long as the first beam can be diffracted to obtain a plurality of second beams of different wavelengths, of course, relatively structurally Adjust accordingly. The focusing lens 14 focuses the two second light beams having different wavelengths, so as to obtain two third light beams that each move toward their focus after focusing. This embodiment includes two micro-optical element arrays 10, 15 and each micro-optical element array includes a plurality of micro-optical elements. One of the important points of the present invention is that these micro-optical elements process these separately. A third light beam to obtain a plurality of fourth light beams. For example, the first micro-optical element array 10 is composed of a plurality of micro-focusing lens arrays having different focal lengths, so that the focal points of these fourth beams can be aligned on the same plane, which overcomes the traditional focus of multiple beams with different wavelengths. Disadvantages of arc surface. For another example: the second micro-optical element array 15 may be composed of a plurality of light-emphasis controllers, which can even control whether to turn off the light beams of certain wavelengths, that is, turn off the signal of a certain channel. As those skilled in the art can easily know, there are two micro-optical element arrays in this embodiment. In fact, the present invention does not limit the number of micro-optical element arrays. Please continue to refer to FIG. 1. These fourth light beams are finally coupled to a plurality of light receiving devices, here are the receiving optical fibers 18, and these receiving optical fibers 18 are sent to an appropriate processing device, and the processing of the data signals of each channel is continued. . The micro-optical element array of the present invention can not only make the focus points of the fourth light beams align on the same plane, but also can adjust the intensity of the fourth light beams respectively received by the light receiving devices by using various methods such as controlling the focus point. Generally, light beams located at intermediate frequencies receive a light intensity

10732twf.ptd Page 15 200428050 V. Description of the invention (7) The micro-optical element array of the present invention can also perform the function of an equalizer. In addition, if the wavelength of the transmitted light beam is shifted due to some reasons, the focus of the light beam that is refocused after splitting does not fall correctly in the receiving range of the light receiving device, so that the micro-optical element array cannot be received correctly. The focal length of each light beam is adjusted individually, for example, slightly out of focus, so that these light receiving devices can receive the corresponding light beam again, that is, the channel bandwidth of the fourth light beam respectively received by these light receiving devices is adjusted. Micro-optical element arrays can also achieve the function of controlling spectral effects. If you are familiar with this art, you can easily know that to achieve the above or many other functions, these micro-optical components can be multiple micro-focusing lenses with different focal lengths, or multiple Fresnel micro-lenses (F resne 1 1 ens), or even a plurality of diffractive optical elements, such as a diffractive optical element made of liquid crystal, and so on. Alternatively, the main materials of these micro-optical elements in the micro-optical element array of the present invention may be electrochromic (e 1 ectr 〇chr omic) materials, such as tungsten oxide, manganese oxide, and nickel oxide. And so on, you can use the control voltage to change the characteristics of the beam passed. Otherwise, these micro-optical elements can also be a plurality of light-emphasis controllers, which can individually control the intensity ratio of the fourth beam to the corresponding third beam, or can individually control whether one of these third beams is passed or turned off . _ As shown in the figure, the free space according to the preferred embodiment of the present invention > grating wavelength multiplexer, in which the micro-optical element arrays 10 and 15 each include a silicon wafer holder with at least one opening As the channel of the beam, and

10732twf.ptd Page 16 200428050 V. Description of the invention (8) These micro-optical components are arranged in the opening of the silicon wafer holder. Refer to Figure 2 for details. In addition, if the artist is familiar with this, the free-space grating wavelength multiplexer may further include a collimating lens (not shown), which is suitable for collimating the incident light beam emitted by the optical fiber to obtain the first light beam To reflective grating 1 6. A free-space grating wavelength multiplexer provided by the present invention, wherein the micro-optical element array can be made of a single micro-optical element, the main point is that it can process these third beams separately to obtain a plurality of fourth beams . For example, this micro-optical element can be an active Frean micro-lens array, which is mainly composed of a single diffractive optical element with different focal lengths. Please refer to FIG. 2, which is a schematic structural diagram of an optical element of an active Frean microlens array according to a preferred embodiment of the present invention. The micro-optical element includes a silicon wafer holder 2 2, a liquid crystal layer 2 6, a substrate 27, and a conductive layer 28. The silicon wafer holder 22 has at least one opening 24 as a light beam channel. The substrate 27 generally includes two upper and lower layers, and is made of a light-transmitting thin film material, and is mainly used to sandwich the liquid crystal layer 26. The above-mentioned conductive layer 28 has a patterned electrode defined therein, and this pattern is arranged in the opening 24 of the Shixi wafer holder. The characteristics of light transmission through the liquid crystal layer can be controlled by controlling the voltage applied to the electrode. For example, the shape of the pattern is a Fresnel zone plate. The focus characteristics of the active Fremont micro-lens array can be controlled by controlling the voltage applied to the electrode, such as focus or defocus. and many more. 〇 As mentioned above, since the present invention adopts a micro-optical element array or its equivalent, it can separately process light beams of different wavelengths, and further

10732t.wf.ptd Page 17 200428050 V. Description of the invention (9) The focal points of beams with different wavelengths can be arranged on the same plane to increase optical efficiency. In addition, the intensity of beams with different wavelengths can be adjusted individually, which increases the equalization. The function of the E qua 1 izer, or increase or adjust the channel bandwidth, and even close individual channels. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes and retouch without departing from the spirit and scope of the present invention. The scope of protection of the invention shall be determined by the scope of the attached patent application.

10732twf.ptd Page 18 200428050 Brief Description of Drawings Figure 1 shows a schematic diagram of a free space · grating wavelength multiplexer according to a preferred embodiment of the present invention. FIG. 2 is a schematic structural diagram of an optical element of an active Frean microlens array according to a preferred embodiment of the present invention. Figure 3 is a schematic diagram showing the structure of a conventional free-space grating wavelength multiplexing technique. Figure 4 is a schematic diagram of another free-space grating wavelength multiplexing technology. Description of graphical symbols: 1 0 first micro-optical element array 1 2, 3 2 light source fiber 0 1 4, 3 4 focusing lens 1 5 second micro-optical element array 1 6, 3 6 reflective grating 1 8, 3 8 receiving Optical fiber 2 2 Silicon wafer clamp 24 Opening 2 6 Liquid crystal layer 27 Substrate 28 Conductive layer 46 Concave mirror grating i

10732twf.ptd Page 19

Claims (1)

200428050 6. Scope of patent application 1. A free-space grating wavelength multiplexer comprising:-a grating for diffracting a first light beam to obtain a plurality of second light beams with different wave lengths; a focusing lens To focus the second light beams to obtain a plurality of third light beams; and a micro-optical element array including a plurality of micro-optical elements, the micro-optical elements respectively process the third light beams to obtain a complex number Fourth beam. 2. The free-space grating wavelength multiplexer according to item 1 of the scope of patent application, wherein the fourth light beams are coupled to a plurality of light receiving devices, and the micro-optical element array can make: the focal points of the fourth light beams Align on the same f-plane, adjust any one of the intensity of the fourth light beams received by the light receiving devices, and adjust the channel bandwidth of the fourth light beams received by the light receiving devices. 3. The free-space grating wavelength multiplexer according to item 2 of the scope of patent application, wherein the micro-optical elements are a plurality of micro-focusing lenses having different focal lengths. 4. The free-space grating wavelength multiplexer as described in the second item of the scope of the patent application, wherein the micro-optical elements are a plurality of Fresnel lenses. As described in the second item of the scope of the patent application The free-space grating wavelength multiplexer, wherein the micro-optical elements are a plurality of diffractive optical elements. > 6. The free-space grating wavelength multiplexer according to item 2 of the scope of patent application, wherein the light receiving devices are a plurality of optical fibers. 10732twf.ptd Page 20 200428050 6. Application for patent scope 7. The free-space grating described in item 1 of the patent application has multiple wavelengths. The micro-optical element is made of an electrochromic material. As the main material. 8. The free-space grating wavelength multiplexer according to claim 7 in the scope of the patent application, wherein the electrochromic material comprises any one of hafnium oxide, ferrous oxide, and nickel oxide. 9. The free-space grating wavelength multiplexer described in item 1 of the scope of patent application, wherein the micro-optical elements are a plurality of light-emphasis controllers, and the intensity of the fourth beams and the third beams can be controlled individually Either the ratio or each of the third light beams is controlled. 10 · The free-space grating wavelength multi-diameter multiplexer according to item 1 of the scope of the patent application, wherein the micro-optical element array further includes a silicon wafer holder having at least one opening as a light beam channel, and the micro An optical element is disposed in the opening of the broken wafer holder. 1 1 · The free-space grating wavelength multiplexer described in item 1 of the scope of patent application, further comprising a collimating lens, adapted to collimate an incident beam to obtain the first beam incident on the reflective grating . 1 2. A free-space grating wavelength multiplexer comprising: a grating for diffracting a first light beam to obtain a plurality of second light beams of different wavelengths; a focusing lens for changing the first light beams; Focusing two beams to obtain a plurality of third beams; and a micro-optical element, each of which processes the third beams separately to obtain a plurality of fourth beams. 10732twf.ptd Page 21 200428050 VI. Patent application scope 1 3 · Free space grating wavelength multiplexer as described in item 12 of the patent application scope, wherein the fourth beams are coupled to a plurality of optical fibers, the micro-optics. The element array can make: the focal points of the fourth beams are arranged on the same plane, adjust the intensity of the fourth beams received by the optical fibers, and adjust the channel frequency of the fourth beams received by the optical fibers. Any of the broad three --- 1 4 · The free-space grating wavelength multiplexer as described in item 13 of the scope of patent application, wherein the micro-optical element is an active Fresnel micro lens (F resne 1 1 ens) array, the active Forex Microlens array is a diffractive optical element with a different focal length. 15. The free-space grating wavelength f multiplexer according to item 14 of the scope of patent application, wherein the micro-optical element includes: a silicon wafer holder having at least one opening as a channel for a light beam; a liquid crystal A substrate, made of a light-transmissive thin film material, for sandwiching the liquid crystal layer; and a conductive layer, which includes an electrode defining a pattern, the pattern is disposed in the opening of the silicon wafer holder, and By controlling the magnitude of the voltage applied to the electrode, the characteristics of light transmitting through the liquid crystal layer are controlled. 16. The free-space grating wavelength multiplexer according to item 15 of the scope of patent application, wherein the pattern shape is a Fresnel zone plate (Fresne 1 ζ ο ne ^ p 1 ate), which is added to The voltage of the electrode can control the focus of the active Frean microlens array. 10732twf.ptd Page 22