JP2007003812A - Optical multiplexing/demultiplexing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical multiplexing/demultiplexing device that reduces optical coupling loss and equalizes loss of each wavelength. <P>SOLUTION: The optical multiplexing/demultiplexing multiplexes a light beam comprising different wavelengths λ<SB>1</SB>-λ<SB>8</SB>into one optical fiber or demultiplexes from one optical fiber, in which the different wavelengths λ<SB>1</SB>-λ<SB>8</SB>are multiplexed, includes an optical edge filter 150 by which the light beams comprising of the wavelengths λ<SB>1</SB>-λ<SB>8</SB>are made to enter and separate into first and second light beams, and also includes a plurality of optical bandpass filters 111-118 with which the first and second light beam groups are each separated into a single wavelength. By this optical edge filter 150, the number of wavelengths is separated equally, for example, into light beams comprising λ<SB>1</SB>-λ<SB>4</SB>and those comprising λ<SB>5</SB>-λ<SB>8</SB>, and thereafter, the light beams of each wavelength are extracted by the optical bandpass filters 111-118 that transmit only specified wavelengths. With such a structure, since maximum optical path length of light beams will be shortened, optical coupling loss is reduced and substally uniformizing of the coupling loss of each wavelength is available. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical multiplexer / demultiplexer, and more particularly to an optical multiplexer / demultiplexer that demultiplexes light having a plurality of wavelengths into each single wavelength, or combines light having a plurality of single wavelengths.

  In an optical fiber wavelength division multiplex transmission system, a multiplexer for combining and combining a plurality of signal lights having different wavelengths into one optical fiber, and a plurality of multiplexed wavelengths on a single optical fiber. And a branching filter for separating the signal light.

  A conventional optical multiplexer / demultiplexer 10 includes, for example, nine collimators 40 to 48 and eight optical bandpass filters 11 to 18 as shown in FIG. 4 (for example, Non-Patent Document 1). reference). The collimator 40 includes an optical fiber 20 that transmits light and a lens 30, and the collimators 41 to 48 have the same configuration as the collimator 40. At this time, the tip of the optical fiber 20 in the collimator 40 is disposed at the focal position of the lens 30. The light emitted radially from the optical fiber 20 by the collimator 40 is converted into a parallel light beam after passing through the lens 30. The optical bandpass filters 11 to 18 have a property of transmitting only light of a specific wavelength and reflecting other wavelengths.

In such an optical wavelength division multiplexer 10, for example, a collimator 40, 8 wavelengths lambda ₁ to [lambda] ₈ functions as a signal port of the optical signal to the multiplexing. The collimator 41 has a wavelength λ ₁ , the collimator 42 has a wavelength λ ₂ , the collimator 43 has a wavelength λ ₃ , the collimator 44 has a wavelength λ ₄ , the collimator 45 has a wavelength λ ₅ , the collimator 46 has a wavelength λ ₆ , and the collimator 47 has a wavelength λ _7. the collimator 48 as a signal port of the optical signal having a wavelength lambda _8, respectively function.

Light 8 wavelengths lambda ₁ to [lambda] ₈ is multiplexed and is incident through the collimator 40 from the optical fiber 20 is converted into parallel light beams by a lens 30, enters the optical bandpass filter 11 Is done. The optical bandpass filter 11 has a function of transmitting only light having a wavelength λ ₁ and reflecting light having other wavelengths λ _{2 to} λ ₈ . Therefore, the light of wavelength λ ₁ passes through the optical bandpass filter 11, enters the lens 31 of the collimator 41, is collected by the lens 31, and then enters the optical fiber 21. In this way, only one wavelength out of the multiplexed light transmitted through the optical fiber 20 is transmitted through the optical bandpass filter 11 and coupled to the optical fiber 21.

On the other hand, light having wavelengths λ _{2 to} λ ₈ is reflected by the optical bandpass filter 11 and enters the optical bandpass filter 12. As described above, the optical bandpass filter 12, the wavelength lambda _2, is separated into light of another wavelength lambda ₃ to [lambda] _8, light of the wavelength lambda ₂ that has passed through the optical bandpass filter 12, the lens of the collimator 42 32 enters the optical fiber 22 and is coupled to the optical fiber 22. Then, light having wavelengths λ _{3 to} λ ₈ is reflected by the optical bandpass filter 12 and enters the optical bandpass filter 13. Thereafter, the light of wavelengths λ _{3 to} λ ₈ is similarly transmitted through the optical bandpass filters 13 to 18 so as to transmit only light of a predetermined single wavelength and coupled to the optical fibers 23 to 28. As described above, the optical multiplexer / demultiplexer 10 separates the light multiplexed with 8 wavelengths into light of each wavelength.

  Further, in the optical multiplexer / demultiplexer 10, the light can be multiplexed by reversing the traveling direction of the light. That is, light of different wavelengths incident from the signal ports corresponding to the collimators 41 to 48 can be incident on the signal port corresponding to the collimator 40 as one multiplexed light.

“SpectraMux ™, A Compact CWDM Solution with low cost, Low IL & Extended Temperature”, Alliance Fiber Optic Products, Inc. 19 February 2004 AFOP Confidential Material

  However, the optical multiplexer / demultiplexer 10 configured as described above has the following problems.

  First, since the distance between the collimators facing each other differs for each signal port, the coupling loss of each port is not constant. As is well known, since the optical coupling loss between the collimators depends on the distance, the optical coupling loss occurs in any case. In the conventional optical multiplexer / demultiplexer 10, as shown in FIG. 4, the optical path length between the collimator 40 and the collimator 48 is several times longer than the optical path length between the collimator 40 and the collimator 41. For this reason, there is a problem that the optical coupling loss between the collimator 40 and the collimator 48 is large, and the insertion loss characteristic most important in the optical signal demultiplexer is increased.

  Another problem is that the optical coupling system tends to become unstable. For example, in the optical multiplexer / demultiplexer 10 shown in FIG. 4, the light beam emitted from the collimator 40 is more incident on the optical bandpass filters 11 to 18 as the light beam is incident on the collimator 40 located farther from the collimator 40 on the optical path. The optical fiber is optically coupled with the number of reflections increased. At this time, when the angle of any one of the optical bandpass filters 11 to 18 changes due to, for example, temperature or vibration, the traveling direction of the light beam reflected by the optical bandpass filter whose angle has changed and the original reflected light. There is an error between the correct direction of travel. For this reason, there is a problem in that the optical coupling with the collimator that receives the light beam having a deviation in the traveling direction is broken, and the optical coupling is deteriorated. Therefore, as the number of reflections by the optical bandpass filter increases, there is a higher possibility that such optical coupling deterioration occurs, and the optical coupling system tends to become unstable.

  Furthermore, in an optical demultiplexer having multiple channels, there is a problem that mounting is difficult because the interval between adjacent collimators is narrow. For example, as shown in FIG. 4, the collimators 41, 43, 45, and 47 are adjacently arranged substantially in parallel, and the collimators 42, 44, 46, and 48 are adjacently arranged substantially in parallel. In general, when a collimator is mounted, optical adjustment is performed using a special jig or the like so as to minimize the coupling loss while observing the optical coupling loss, and is fixed at an optimal adjustment position. At this time, if the interval between the collimators is narrow, jigs and the like mechanically interfere with each other, which hinders manufacturing. In particular, when three or more collimators are mounted adjacent to each other, there is a problem that significant interference occurs and manufacturing becomes difficult, resulting in an increase in manufacturing cost. In addition, since the interval between adjacent collimators and optical bandpass filters is narrow, conventionally, the collimator is fixed using an adhesive. However, the adhesive has low adhesive strength and the adhesive strength tends to be chemically unstable, and there is a problem in the long-term reliability of the optical multiplexer / demultiplexer.

  In addition, when a conventional optical multiplexer / demultiplexer is used in a wavelength division multiplexing transmission system, the same optical multiplexer / demultiplexer cannot be used on the transmission side and the reception side. For example, as shown in FIG. 5, an 8-wavelength multiplexer 10A is used on the transmitting side, and an 8-wavelength demultiplexer 10B is used on the receiving side. As described above, in this type of multiplexer / demultiplexer, it is extremely difficult to achieve the same low-loss coupling in all eight wavelength signal ports, and the coupling loss in each signal port is non-uniform.

In order to avoid such non-uniformity of the coupling loss, in the conventional multiplexer 10A, the wavelengths λ _{1 to} λ ₈ are incident and combined in the order of the first to eighth signal ports, and the demultiplexer In 10B, light is emitted from the first to eighth signal ports in the order of wavelengths λ _{8 to} λ ₁ . In other words, the wavelengths assigned to the signal ports of the multiplexer 10A and the demultiplexer 10B are inverted and arranged so that the loss of each wavelength in the entire transmission system is made uniform. For this reason, when applied to a wavelength division multiplexing transmission system, there has been a problem that the multiplexer 10A and the demultiplexer 10B must always be used as a pair.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to reduce the optical coupling loss, stabilize the optical coupling system, and make the coupling loss of each wavelength uniform. It is an object of the present invention to provide a new and improved optical multiplexer / demultiplexer capable of performing the above.

In order to solve the above-described problem, according to _one aspect of the present invention, light having a wavelength of λ ₁ to λ ₈ is multiplexed into one, or one light having a wavelength of λ _{1 to} λ ₈ is demultiplexed. An optical edge filter (Edge Filter) that receives light having a wavelength of λ ₁ to λ ₈ and separates the light into a first light group and a second light group; And a plurality of optical bandpass filters that separate the first light group and the second light group into respective single wavelengths.

Such an optical multiplexer / demultiplexer has, for example, a plurality of collimators configured by integrating an optical fiber and a lens. This collimator is divided into one common signal port for coupling light multiplexed with wavelengths λ _{1 to} λ ₈ and a plurality of signal ports for coupling separated light. For example, when light having 8 wavelengths of wavelengths λ _{1 to} λ ₈ incident from the common signal port is separated into light of each wavelength and coupled to each signal port, the light having 8 wavelengths is _first divided into 2 Separated into two light groups. A plurality of optical bandpass filters that transmit only specific wavelengths are disposed on the optical path of each separated light group, and only the wavelengths that have passed through the optical bandpass filters can be extracted. With this configuration, the maximum optical path length of the first and second light groups can be shortened, and the light coupling loss can be reduced.

The optical edge filter of the optical multiplexer / demultiplexer having such a configuration can separate light having a wavelength of λ _{1 to} λ ₈ by transmitting the first light group and reflecting the second light group, for example. it can. For example, a long wavelength transmission filter or a short wavelength transmission filter can be used as the optical edge filter. Further, the first light group transmitted through the optical edge filter is totally reflected by the light reflector arranged on the same straight line as the optical path of the light having the wavelength of incident λ ₁ to λ ₈ . The optical path of the second light group can be made substantially symmetrical with the optical path of the second light group reflected by the optical edge filter. Here, for example, a mirror can be used as the light reflector.

At this time, the optical edge filter, lambda ₁ light consisting of wavelengths to [lambda] _8, may be equally divided into the light composed of wavelengths of light and lambda ₅ to [lambda] ₈ consisting of wavelengths of lambda ₁ to [lambda] ₄ . As a result, the maximum optical path difference between the two optical paths can be minimized, and the coupling loss of each signal port in the optical multiplexer / demultiplexer can be made substantially uniform. Further, a plurality of optical bandpass filter, by the first to eighth optical bandpass filter corresponding to each wavelength of lambda ₁ to [lambda] _8, the multiplexed light to the eight wavelengths, light of each wavelength It is possible to form an optical multiplexer / demultiplexer that can be separated into two.

  Further, the plurality of optical bandpass filters for separating the first light group and the light reflector are disposed to be inclined in the positive direction by a predetermined angle (for example, about 12 °) with respect to the straight line. The plurality of optical bandpass filters for separating the light groups and the optical edge filter may be arranged so as to be inclined in the negative direction by a predetermined angle (for example, about 12 °) with respect to the straight line. it can. With this configuration, the optical path of the first light group can be made substantially symmetric with the optical path of the second light group reflected by the optical edge filter, and the maximum of the first light group and the second light group can be obtained. The optical path difference can be minimized.

  Further, with the configuration of the optical multiplexer / demultiplexer, the number of adjacent collimators can be reduced, so that a space is generated around the collimator. This facilitates the installation of optical components such as a collimator and an optical bandpass filter, and these can be fixed by welding with, for example, a YAG laser instead of an adhesive. The long-term reliability of the vessel can also be improved.

  Further, such an optical multiplexer / demultiplexer can be applied not only to light of 8 wavelengths but also to light of 6 wavelengths, for example, and it is possible to reduce and make the coupling loss of each signal port uniform. .

  As described above, according to the present invention, it is possible to provide an optical multiplexer / demultiplexer that can reduce the optical coupling loss, stabilize the optical coupling system, and make the coupling loss of each wavelength uniform. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
First, an optical multiplexer / demultiplexer according to a first embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 is an explanatory diagram showing the configuration of the optical multiplexer / demultiplexer according to the first embodiment.

The optical multiplexer / demultiplexer 100 according to the present embodiment, for example, combines or demultiplexes light having wavelengths λ _{1 to} λ _{8. As} shown in FIG. 1, nine collimators 140 to 148 and eight The optical band pass filters 111 to 118, the optical edge filter 150, and the optical reflector 160 are configured. Here, the wavelength lambda ₁ to [lambda] ₈ is intended in ascending order of lambda ₈ from the wavelength lambda _1.

  The collimator 140 includes an optical fiber 120 that transmits light and a lens 130, and is fixed to a case (not shown) of the optical multiplexer / demultiplexer 100 by welding with, for example, a YAG laser. . The collimators 141 to 148 have the same configuration as the collimator 140. At this time, the tip of the optical fiber 120 in the collimator 140 is disposed at the focal position of the lens 130. The light emitted radially from the optical fiber 120 by the collimator 140 is converted into a parallel light beam after passing through the lens 130.

The optical bandpass filters 111 to 118 have a property of transmitting only light of a specific wavelength and transmitting light of other wavelengths. The optical edge filter 150 is a filter that transmits only wavelengths in a specific region and reflects other wavelengths. For example, light in a short wavelength band of wavelengths λ _{1 to} λ ₄ is reflected and wavelengths λ _{5 to} λ are reflected. _This is an optical edge filter that transmits light having a long wavelength band of ₈ . The light reflector 160 is a mirror, for example, and has a function of totally reflecting incident light. The optical bandpass filters 111 to 118, the optical edge filter 150, and the optical reflector 160 are fixed to the case (not shown) of the optical multiplexer / demultiplexer 100 by welding with a YAG laser through a metal holder. ing.

Here, nine collimator 140-148, for example, a collimator 140 functions as a common signal port of the optical signal 8 wavelengths lambda ₁ to [lambda] ₈ is multiply. The collimator 141 has a wavelength λ ₁ , the collimator 142 has a wavelength λ ₂ , the collimator 143 has a wavelength λ ₃ , the collimator 144 has a wavelength λ ₄ , the collimator 145 has a wavelength λ ₅ , the collimator 146 has a wavelength λ ₆ , and the collimator 147 has a wavelength λ _7. , collimator 148 as a signal port of the optical signal having a wavelength lambda _8, respectively function.

  In the optical multiplexer / demultiplexer 100, a collimator 140, which is a common signal port, an optical edge filter 150, and an optical reflector 160 are arranged on a straight line, and on both sides, four collimators and four optical bands are arranged. A pass filter is provided. At this time, the optical bandpass filters 111 to 114 are disposed substantially parallel to the optical edge filter 150, and the optical bandpass filters 115 to 118 are disposed substantially parallel to the light reflector 160. . In addition, collimators 141 to 148 corresponding to the optical bandpass filters 111 to 118 are provided, respectively.

  Next, the operation of the optical multiplexer / demultiplexer 100 according to this embodiment as a demultiplexer will be described.

The light multiplexed through the eight wavelengths λ _{1 to} λ ₈ transmitted through the optical fiber 120 in FIG. 1 is converted into a parallel light beam by the collimator 140 as described above. This light beam is incident on an optical edge filter 150 disposed to be inclined by θ (for example, about 12 ° in the negative direction (counterclockwise)) with respect to the traveling direction of the light beam. Here, the optical edge filter 150 is a filter that transmits light having a wavelength of λ _c or more located between the wavelengths λ ₄ and λ ₅ and reflects light having a wavelength of less than the wavelength λ _c . Accordingly, light having wavelengths λ _{1 to} λ ₄ smaller than wavelength λ _c is reflected, and light having wavelengths λ _{5 to} λ _{8 that} are longer than wavelength λ _c is transmitted.

Light having wavelengths λ _{1 to} λ ₄ reflected by the optical edge filter 150 is incident on the optical bandpass filter 111. Here, the optical band-pass filter 111 transmits only light of the wavelength lambda _1. Therefore, the light of wavelength λ ₁ passes through the optical bandpass filter 111 and enters the collimator 141, is collected by the lens 131, and is coupled to the optical fiber 121. On the other hand, light having wavelengths λ _{2 to} λ ₄ is reflected by the optical bandpass filter 111 and enters the optical bandpass filter 112.

Light of the wavelength lambda ₂ to [lambda] ₄ incident on the light band-pass filter 112, similarly, only the light of wavelength lambda ₂ is transmitted through the optical bandpass filter 112 is incident on the collimator 142, the wavelength lambda _3, the lambda ₄ The light is reflected by the optical bandpass filter 112 and enters the optical bandpass filter 113. Then, the wavelength lambda ₃ enters the optical bandpass filter _113, the light of lambda _4, only light of the wavelength lambda ₃ is transmitted through the optical band-pass filter 113, it enters the collimator 143. Meanwhile, light of wavelength lambda _4, which is reflected in the optical band-pass filter 113 is transmitted through the optical band-pass filter 114, enters the collimator 144. The optical bandpass filters 111 to 114 are disposed substantially parallel to the optical edge filter 150.

Further, the light having the wavelengths λ _{5 to} λ ₈ that has passed through the optical edge filter 150 is reflected by the light reflector 160 and enters the optical bandpass filter 115. Here, the light reflector 160 has θ (for example, about 12 ° in the positive direction (clockwise) in the direction opposite to the optical edge filter 150 with respect to the traveling direction of the light beam on which the wavelengths λ _{1 to} λ ₈ are superimposed. ). Therefore, the light with wavelengths λ _{5 to} λ ₈ is reflected to the opposite side of the light with wavelengths λ _{1 to} λ ₄ across the optical edge filter 150 and the light reflector 160. Then, similarly to separating the light of the wavelengths λ _{1 to} λ ₄ into each wavelength, the light of the wavelengths λ _{5 to} λ ₈ is separated by the optical bandpass filters 115 to 118, and the light of each wavelength is Each is taken out from the corresponding optical fiber. The optical bandpass filters 115 to 118 are disposed substantially parallel to the light reflector 160.

The operation of the optical multiplexer / demultiplexer 100 according to the present embodiment as a demultiplexer has been described above. On the other hand, when the optical multiplexer / demultiplexer 100 operates as a multiplexer, an operation opposite to the operation as the above-described duplexer is performed. That is, the light of each wavelength λ _{1 to} λ ₈ incident on the multiplexer / demultiplexer 100 from the optical fibers 121 to 128 is converted into parallel light beams by the collimators 141 to 148, respectively, and the optical bandpass filters 111 to 118 are converted. Transparent. Thereafter, light having wavelengths λ _{5 to} λ ₈ is reflected by the light reflector 160, passes through the optical edge filter 150, and enters the collimator 140. Further, light having wavelengths λ _{1 to} λ ₄ is reflected by the optical edge filter 150 and enters the collimator 140. Then, the light with wavelengths λ _{1 to} λ ₈ collected by the lens 130 is coupled to the optical fiber 120.

  Such a configuration of the optical multiplexer / demultiplexer 100 produces the following effects.

  First, compared with a conventional optical multiplexer / demultiplexer, there is an effect that the coupling loss at each signal port can be made uniform and low by shortening the optical path length between collimators. As described above, generally, when the distance between the collimators facing each other is increased to some extent, the coupling loss between the optical fibers that couple them increases rapidly. For this reason, in the configuration of the conventional optical multiplexer / demultiplexer, the optical path between the collimator (for example, the collimator 40 in FIG. 4) that is a common signal port and the collimator (for example, the collimator 48 in FIG. 4) that is spaced apart on the optical path at the maximum. It is difficult to shorten the length, and the optical coupling loss increases.

On the other hand, the optical multiplexer / demultiplexer 100 according to the present embodiment converts light of wavelengths λ _{1 to} λ ₈ into light of wavelengths λ _{1 to} λ ₄ and light of wavelengths λ _{5 to} λ ₈ by the optical edge filter 150. It is the structure which isolate | separates into. That is, by separating the superposed light into two groups, the number of reflections by the optical bandpass filter before being separated into each wavelength is reduced, and the maximum distance between collimators can be shortened. Therefore, the coupling loss of light can be reduced. Further, since the optical path difference between the first separated light and the last separated light becomes small, the coupling loss can be made substantially uniform.

  For example, when light having 8 wavelengths of 1471 nm, 1491 nm, 1511 nm, 1531 nm, 1551 nm, 1571 nm, 1591 nm, and 1611 nm is demultiplexed using the optical multiplexer / demultiplexer 100 according to the present embodiment, the insertion loss is represented by the following table. The result shown in 1 was obtained.

  The insertion loss in the conventional multiplexer / demultiplexer is 1.2 to 2.0 dB, and the insertion loss deviation is 1.0 to 1.5 dB. On the other hand, as shown in Table 1, the maximum insertion loss when demultiplexed by the optical multiplexer / demultiplexer 100 according to the present embodiment is about 0.52 dB, and the insertion loss deviation is about 0.12 dB. Therefore, it can be seen that the insertion loss of the optical multiplexer / demultiplexer 100 according to the present embodiment is extremely small compared to the conventional one, and the insertion loss can be reduced.

  Further, the optical multiplexer / demultiplexer 100 according to the present embodiment has a stable optical coupling system. In general, in a light beam coupling system that repeats multiple reflections, the mechanical stability of optical components having a reflection function (in this embodiment, an optical bandpass filter, an optical edge filter, and a light reflector), in particular, angle stability is optical coupling. It greatly affects the stability of the system. For example, when the installation angle of the reflective optical component is changed, the angle of the reflected light beam is changed, and the optical coupling between the collimators is deteriorated. Such deterioration tends to occur as the number of reflecting optical parts increases, that is, as the number of reflections increases, and the amount of deterioration tends to increase.

  The optical multiplexer / demultiplexer 100 according to the present embodiment is configured to separate the superimposed light into two groups, and therefore is reflected by the optical edge filter 150 and then passes through the optical bandpass filters 111 to 114. Two independent optical paths are formed: the first optical path and the second optical path through the optical bandpass filters 115 to 118 after being transmitted through the optical edge filter 150 and reflected by the light reflector 160. . At this time, the maximum number of reflections of light in the first and second optical paths is four, compared with the number of reflections in the conventional optical multiplexer / demultiplexer (for example, seven in the optical multiplexer / demultiplexer in FIG. 4). , The number of light reflections is reduced. As a result, the influence of the reflective optical component is reduced, and the stability of the optical coupling system of the optical multiplexer / demultiplexer 100 is improved.

  Furthermore, the optical multiplexer / demultiplexer 100 according to the present embodiment has an advantage that the number of adjacent collimators is as small as two, so that the collimator can be easily mounted. Generally, the mounting position of the collimator is determined by observing the final coupling amount while optically adjusting using a mechanical fine movement table or the like. At this time, if three or more collimators are adjacent to each other, it is very difficult to fix the collimator. For example, when three collimators are adjacent to each other, the distance between the collimator located in the center and the collimators located on both sides thereof is narrow, so that the degree of adjustment of the collimator located in the center is limited. Furthermore, mechanical interference with the adjustment jig that holds the collimator tends to occur, which often hinders manufacturing.

  On the other hand, with the configuration such as the optical multiplexer / demultiplexer 100 according to the present embodiment, the number of adjacent collimators can be set to 2, for example, and a space is secured on the side opposite to the adjacent surface of the collimator. For this reason, it is possible to make a large adjustment jig. Although the four collimators 142, 144, 146, and 148 appear to be adjacent to each other, there is actually a sufficient space between the collimator 142 and the collimator 146. Accordingly, the collimator 142, the collimator 144, the collimator 146, and the collimator 148 are only adjacent to each other. Furthermore, by having such a space, the collimator according to the present embodiment can be fixed by welding with a YAG laser. Thereby, compared with the case where it fixes with an adhesive agent, adhesive strength increases, and the long-term reliability of an optical multiplexer / demultiplexer can be improved.

  Further, the optical multiplexer / demultiplexer 100 according to the present embodiment has an advantage that it is not necessary to use the multiplexer and the duplexer as a pair. As described above, the multiplexer and the duplexer essentially have the same function. However, since the insertion loss of each signal port is not uniform in the conventional optical multiplexer / demultiplexer, the wavelength arrangement of each signal port of the multiplexer / demultiplexer is reversed at both ends of the wavelength division multiplexing transmission system. By doing so, the insertion loss of each wavelength was made uniform throughout the transmission system.

  In contrast, the insertion loss of each signal port of the optical multiplexer / demultiplexer 100 according to the present embodiment is uniform. That is, there is no difference in characteristics between the multiplexer and the demultiplexer when the wavelength arrangement of each signal port is the same. For this reason, the same optical multiplexer / demultiplexer can be used for the multiplexer and the duplexer. Therefore, there is no installation mistake between the multiplexer and the demultiplexer in the installation work, and it is difficult to cause confusion in terms of management. In addition, because the multiplexer and duplexer are compatible, manufacturing is easy, and even if one of them fails, it can be replaced regardless of the model.

  The optical multiplexer / demultiplexer 100 according to the first embodiment has been described above. Such an optical multiplexer / demultiplexer 100 can reduce the maximum optical path length required to multiplex or demultiplex light. Thereby, the coupling loss of light can be reduced, and the coupling loss in each signal port can be made substantially uniform. In addition, since the maximum number of reflections of light can be reduced, the optical coupling system is stable. Furthermore, since there are only two adjacent collimators, even if the interval between the adjacent collimators is small, there is a surplus space in the outer peripheral portion where the adjacent collimators do not face each other, so it is easy to mount the collimator. There is an effect.

  Next, an optical multiplexer / demultiplexer 200 according to the second embodiment will be described with reference to FIG. Here, FIG. 2 is an explanatory diagram showing an optical multiplexer / demultiplexer 200 according to the second embodiment.

(Second Embodiment)
As shown in FIG. 2, the optical multiplexer / demultiplexer 200 according to the second embodiment includes nine collimators 240 to 248, eight optical bandpass filters 211 to 218, an optical edge filter 250, and an optical reflector 260. And is configured. Here, the length of the wavelength lambda ₁ to [lambda] ₈ is intended in ascending order of lambda ₈ from the wavelength lambda _1. The collimators 240 to 248, the optical bandpass filters 211 to 218, and the optical reflector 260 are the same as those of the optical multiplexer / demultiplexer 100 according to the first embodiment. The configuration of the optical multiplexer / demultiplexer 200 according to the present embodiment is the same as the configuration of the optical multiplexer / demultiplexer 100 according to the first embodiment, and thus detailed description thereof is omitted.

The optical multiplexer / demultiplexer 200 according to the present embodiment is different from the optical multiplexer / demultiplexer 100 according to the first embodiment in the optical edge filter 250. The optical edge filter 250 according to the present embodiment is a short wavelength optical edge filter, light having wavelengths λ _{1 to} λ ₄ is transmitted through the optical edge filter 250, and light having wavelengths λ _{5 to} λ ₈ is optical edge filter. 250 is reflected.

The light separated by the optical edge filter 250 into the light of the wavelengths λ _{1 to} λ _{4 and} the light of the wavelengths λ _{5 to} λ ₈ is separated into each wavelength as in the optical multiplexer / demultiplexer 100 of the first embodiment. Each is incident on a corresponding collimator, collected by a lens, and coupled to an optical fiber.

  The optical multiplexer / demultiplexer 200 according to the second embodiment has been described above. With this optical multiplexer / demultiplexer 200, the maximum optical path length required to multiplex or demultiplex light can be shortened, as in the optical multiplexer / demultiplexer 100 according to the first embodiment. Thereby, the coupling loss of light can be reduced, and the coupling loss in each signal port can be made substantially uniform. In addition, since the maximum number of reflections of light can be reduced, the optical coupling system is stable. Furthermore, since there are only two adjacent collimators, even if the interval between the adjacent collimators is small, there is a surplus space in the outer peripheral portion where the adjacent collimators do not face each other, so it is easy to mount the collimator. There is an effect.

  Next, an example of a wavelength division multiplexing transmission system using the optical multiplexer / demultiplexer 100 according to the first embodiment will be described with reference to FIG. FIG. 3 is an explanatory diagram showing an embodiment of the wavelength division multiplexing transmission system.

(Example)
As shown in FIG. 3, two optical multiplexers / demultiplexers 100 according to the first embodiment, for example, the first optical multiplexer / demultiplexer 100A as a demultiplexer and the second optical multiplexer / demultiplexer 100B as a multiplexer are combined. A common signal port of each of the optical multiplexers / demultiplexers 100A and 100B is connected by a transmission line fiber 170. As described above, in the first optical multiplexer / demultiplexer 100A and the second optical multiplexer / demultiplexer 100B, the insertion loss at each signal port corresponding to each wavelength is substantially uniform. Therefore, it is not necessary to consider the insertion loss of each signal port, and it is not necessary to use a duplexer and a multiplexer as a pair.

  Thus, in the wavelength division multiplexing transmission system, by using the optical multiplexer / demultiplexer 100 according to the first embodiment, the same optical multiplexer / demultiplexer can be used for the demultiplexer and the multiplexer. Module management is also easy. In this example, the optical multiplexer / demultiplexer 100 according to the first embodiment is used. However, the optical multiplexer / demultiplexer 200 according to the second embodiment can also be used.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, an optical multiplexer / demultiplexer that multiplexes / demultiplexes light of 8 wavelengths has been described. However, the present invention is not limited to this example, and may be, for example, 6 wavelengths, and the maximum optical path length of the optical multiplexer / demultiplexer. Can be shortened. In addition, when there are a large number of wavelengths to be combined, an optical edge filter that separates the two light groups can be installed to reduce the number of reflections by the optical bandpass filter and further reduce the maximum optical path length. It becomes possible to do.

  Further, in the above embodiment, the light of 8 wavelengths is separated into two light groups having 4 wavelengths. However, the present invention is not limited to this example, and may be separated into, for example, three or more light groups.

  Furthermore, in the optical multiplexer / demultiplexers 100 and 200 according to the above-described embodiment, as shown in FIG. 1 or FIG. 2, two collimators are disposed adjacent to each other. However, the collimators are disposed not to be adjacent to each other. You can also.

  The present invention can be applied to an optical multiplexer / demultiplexer, and in particular, can be applied to an optical multiplexer / demultiplexer that demultiplexes light having a plurality of wavelengths into each single wavelength, or combines light having a plurality of single wavelengths. .

It is explanatory drawing which shows the optical multiplexer / demultiplexer concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the optical multiplexer / demultiplexer concerning the 2nd Embodiment of this invention. It is explanatory drawing which shows the Example of the wavelength multiplexing transmission system using the optical multiplexer / demultiplexer concerning 1st Embodiment. It is explanatory drawing which shows the structure of the conventional optical multiplexer / demultiplexer. It is explanatory drawing which shows the Example of the wavelength multiplexing transmission system using the conventional optical multiplexer / demultiplexer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical multiplexer / demultiplexer 111-118 Optical band pass filter 120-128 Optical fiber 130-138 Lens 140-148 Collimator 150 Optical edge filter 160 Optical reflector 170 Transmission path fiber

Claims (10)

An optical multiplexer / demultiplexer for multiplexing light having different wavelengths λ _{1 to} λ ₈ into one optical fiber or demultiplexing from one optical fiber multiplexed with different wavelengths λ _{1 to} λ ₈ :
An optical edge filter that receives light multiplexed with wavelengths λ _{1 to} λ ₈ and separates the light into a first light group and a second light group;
A plurality of optical bandpass filters for separating the first light group and the second light group into single wavelengths;
An optical multiplexer / demultiplexer characterized by comprising: The optical edge filter separates light having a wavelength of λ _{1 to} λ ₈ by transmitting the first light group and reflecting the second light group,
The first light group transmitted through the optical edge filter is totally reflected by a light reflector arranged on the same straight line as an optical path of light having a wavelength of the incident λ ₁ to λ _8. The optical multiplexer / demultiplexer according to claim 1. The optical edge filter separates light having a wavelength of λ _{1 to} λ ₈ into light having a wavelength of λ ₁ to λ ₄ and light having a wavelength of λ _{5 to} λ ₈ , The optical multiplexer / demultiplexer according to claim 1. The plurality of optical bandpass filters are composed of first to eighth optical bandpass filters corresponding to the wavelengths λ _{1 to} λ ₈ , respectively. Optical multiplexer / demultiplexer. The plurality of optical bandpass filters for separating the first light group and the optical total reflector are arranged to be inclined in a positive direction by a predetermined angle with respect to the straight line,
The plurality of optical bandpass filters for separating the second light group and the optical edge filter are disposed to be inclined in a negative direction by a predetermined angle with respect to the straight line. Item 5. The optical multiplexer / demultiplexer according to any one of Items 1 to 4. An optical multiplexer / demultiplexer that multiplexes light having different wavelengths λ _{1 to} λ ₆ into one optical fiber or demultiplexes from one optical fiber multiplexed with different wavelengths λ _{1 to} λ ₆ :
An optical edge filter that receives light multiplexed with wavelengths λ _{1 to} λ ₆ and separates the light into a first light group and a second light group;
A plurality of optical bandpass filters for separating the first light group and the second light group into single wavelengths;
An optical multiplexer / demultiplexer characterized by comprising: The optical edge filter separates light having a wavelength of λ _{1 to} λ ₆ by transmitting the first light group and reflecting the second light group,
The first light group transmitted through the optical edge filter is totally reflected by a light reflector arranged on the same straight line as an optical path of light having a wavelength of the incident λ ₁ to λ _6. The optical multiplexer / demultiplexer according to claim 6. The optical edge filter separates light having a wavelength of λ _{1 to} λ ₆ into light having a wavelength of λ ₁ to λ ₃ and light having a wavelength of λ _{4 to} λ ₆ , The optical multiplexer / demultiplexer according to claim 6 or 7. The plurality of optical bandpass filters include first to sixth optical bandpass filters corresponding to the wavelengths λ _{1 to} λ ₆ , respectively. Optical multiplexer / demultiplexer. The plurality of optical bandpass filters for separating the first light group and the optical total reflector are arranged to be inclined in a positive direction by a predetermined angle with respect to the straight line,
The plurality of optical bandpass filters for separating the second light group and the optical edge filter are disposed to be inclined in a negative direction by a predetermined angle with respect to the straight line. Item 10. The optical multiplexer / demultiplexer according to any one of Items 6 to 9.

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