JP2018081254A - Optical multiplexer/demultiplexer and optical transceiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical multiplexer/demultiplexer that can be incorporated into a compact optical transceiver.SOLUTION: Provided is an optical multiplexer/demultiplexer 1a comprising: first to fourth split light input/output units (C1-C4) that correspond to single wavelength lights (L1-L4) and arranged two-dimensionally in the same plane; a single multiplexed light input/output unit C5; second to fourth interference film filters (F2-F4) arranged in front of the second to fourth split light input/output units; and first to third mirrors (M1-M3) arranged in front of the first split light input/output unit and the second to third interference film filters. The output light from the first split light input/output unit alternately traces the first to third mirrors and the second and third interference film filters in ascending order and enters the multiplexed light input/output unit, and the output light from the multiplexed light input/output unit alternately traces the second to fourth interference film filters and the first to third mirrors in descending order, with a light of corresponding wavelength by the second to third interference film filters entering the second and third split light input/output units, a light from the first mirror entering the first split light input/output unit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical multiplexer / demultiplexer and an optical transceiver. Specifically, the present invention relates to an optical multiplexer / demultiplexer using an interference film filter and an optical transceiver miniaturization technique including the optical multiplexer / demultiplexer.

  In optical communication using an optical wavelength division multiplexing (WDM) transmission system, high-speed and large-capacity data transmission is possible by transmitting optical signals having different wavelengths through a single optical fiber. Therefore, the transmission capacity can be increased while using an existing optical fiber cable network without laying a new optical fiber cable.

  At various places in the optical communication network, an optical transmission device is installed that mutually converts an optical signal and an electrical signal, and performs merging, relaying, branching, etc. on a plurality of optical signal transmission paths. The optical transmission apparatus incorporates an optical transceiver for transmitting and receiving optical signals to and from other optical transmission apparatuses and optical transmission lines. The main optical element constituting the optical transceiver corresponding to the WDM transmission system is an optical multiplexer / demultiplexer, and the optical multiplexer / demultiplexer is an optical multiplexer that combines a plurality of optical signals having different wavelengths on the transmission side of the optical transceiver. And a signal obtained by multiplexing optical signals of a plurality of wavelengths propagated through a single optical transmission line (such as an optical fiber) on the receiving side, and is demultiplexed for each wavelength of light. It functions as an optical demultiplexer to be sent to.

  As a method of multiplexing and demultiplexing light in the optical multiplexer / demultiplexer, there are a method using a diffraction grating and a method using an arrayed waveguide grating (AWG), but an interference film made of a dielectric multilayer film is provided. The method using the interference film filter has a simple structure and is cheaper than other methods. An optical multiplexer / demultiplexer using this interference film filter is often used for an optical transceiver in which the interval between wavelengths of multiplexed optical signals is large and the number of transmission channels is not so large.

  In Patent Document 1 below, an optical multiplexer / demultiplexer using an interference film filter is described, and as described in this document, a general optical multiplexer / demultiplexer using an interference film filter is All of the optical signal entrance / exit (hereinafter also referred to as an optical input / output unit) such as the opening end of the optical fiber collimator are linearly arranged. FIG. 1 schematically shows a general optical multiplexer / demultiplexer 1. The illustrated optical multiplexer / demultiplexer 1 uses the open ends of the optical fiber collimators (C1 to C5) as an optical input / output unit. In this example, an optical multiplexer / demultiplexer 1 that individually inputs and outputs four types of single-wavelength light (hereinafter also referred to as monochromatic light) corresponding to four transmission channels is shown. The optical multiplexer / demultiplexer 1 includes four optical fiber collimators (hereinafter also referred to as demultiplexing collimators C1 to C4) as light input / output units serving as entrances / exits of monochromatic light of each wavelength. In addition, one optical fiber collimator (hereinafter also referred to as a combined collimator C5) serving as an input / output unit for light (hereinafter also referred to as multiplexed light) obtained by combining four types of monochromatic light is provided. FIG. 1 shows an optical path when the optical multiplexer / demultiplexer 1 operates as an optical multiplexer.

  As shown in the figure, when the monochromatic lights L1 to L4 in the demultiplexing collimators C1 to C4 are in the front-rear direction and function as an optical multiplexer, the monochromatic lights L1 to L4 are emitted from the rear to the front. Suppose you are. The direction from the rear to the front is the positive direction of the z axis. All the optical fiber collimators C <b> 1 to C <b> 5 are arranged on the flat substrate 10. And let the normal direction of the board | substrate 10 be an up-down direction, and let the direction which goes to the upper direction from the downward direction be a y-axis direction, and let the right-handed xyz coordinate system be set in the figure. Accordingly, FIG. 1A is a zx plan view when the optical multiplexer / demultiplexer 1 is viewed from above, and FIG. 1B is a side view when the optical multiplexer / demultiplexer 1 is viewed from the right rear.

As shown in FIG. 1A, the monochromatic lights L1, L2, L3, and L4 propagating through the optical fibers Fb1, Fb2, Fb3, and Fb4 connected to the rear ends of the demultiplexing collimators C1 to C4. Are respectively λ ₁ , λ ₂ , λ ₃ , and λ _{4. When the} optical multiplexer / demultiplexer 1 operates as an optical multiplexer, the monochromatic lights L 1, L 2, L 3, and L 4 are demultiplexed. Light is emitted forward from the open ends of the collimators C1, C2, C3, and C4. Forward selectively transmits monochromatic light L1~L4 wavelength lambda ₁ to [lambda] ₄ corresponding to each of the respective demultiplexed collimator C1 -C4 are each branching collimators C1 -C4, light other than the transmission wavelength Interference film filters F1 to F4 to be reflected are arranged. The interference film filters F1 to F4 are obtained by forming an interference film on the surface of a parallel plate-like transparent substrate made of quartz glass or the like. The monochromatic lights L1 to L4 emitted from the demultiplexing collimators C1 to C4 are incident on the interference film filters F1 to F4 at a predetermined incident angle θ and are emitted at an emission angle θ.

  On the optical path of outgoing light (L11, L13, L15, L17) from each of the interference film filters F1 to F4, mirrors M1 to M1 are formed by forming a dielectric multilayer film or a metal thin film on the surface of a transparent substrate made of quartz glass or the like. M4 is arranged. The mirrors M1, M2, and M3 respectively reflect the light (L11, L13, L15) traveling forward from the interference film filters F1, F2, and F3 at a reflection angle θ, respectively, so that the interference film filters F2, F3, And F4. Further, the light L17 traveling forward from the interference film filter F4 is specularly reflected by the mirror M4, the opening end of the multiplexing collimator C5 is on the optical path of the specularly reflected light L18, and the optical axis direction of the multiplexing collimator C5 is This coincides with the incident direction of the light L18 reflected by the mirror M4.

In the optical system including the interference film filters F1 to F4 and the mirrors M1 to M4 in the optical multiplexer / demultiplexer 1, the transmitted light from the interference film filters F1 to F4, the reflected light from the mirrors M1 to M4, and the interference film filters F2 to F4. The transmission and reflection are repeated by reflection other than the transmission wavelength on the front surface of the light, and multiplexed light in which the monochromatic lights of wavelengths λ ₁ to λ ₄ are combined is incident on the opening end of the combining collimator C5. The multiplexed light is transmitted to the WDM optical communication network via the optical fiber Fb5 connected to the rear end side of the multiplexing collimator C5. That is, the light is input to an optical transmission line in an optical communication network or an optical element (photodiode or the like) in various devices installed in the optical communication network.

  When the optical multiplexer / demultiplexer 1 shown in FIG. 1 operates as an optical demultiplexer, the multiplexed light L5 propagating through the optical fiber Fb5 connected to the multiplexing collimator C5 is the optical system of the optical multiplexer / demultiplexer 1. The optical path following the above-described L11 to L18 in the ascending order is traced back to the descending order, and the interference film filters F4 to F1 from the light incident from the front to the back with respect to the interference film filters F4 to F1. Monochromatic light having a wavelength transmitted by each of the light beams is input to the demultiplexing collimators C4 to C1. These monochromatic lights are input to various devices installed in the optical communication network via optical fibers Fb4 to Fb1 connected to the demultiplexing collimators C4 to C1. For example, an optical signal superimposed on each monochromatic light is converted into an electrical signal. In connection with the present invention, the following Non-Patent Document 1 describes the standard of the optical transceiver, the configuration of the optical transceiver, and the like.

US Patent Application Publication No. 2003/0099434

Hideaki Kansugi, Kuniyuki Ishii, Satoshi Murayama, Hiromi Tanaka, Hiromi Kurashima, Hiroto Ishibashi, Hideshi Tsumura, "Low-power Optical Transceiver for Data Centers", July 2013 SEI Technical Review No.183, pp.60-64

  In recent years, with the spread of portable information terminals represented by smartphones or cloud computing (SaaS, PaaS, HaaS, network storage, etc.), communication traffic in the optical communication network that is the backbone of data communication networks has increased rapidly. Yes. Therefore, various devices set in the optical communication network, especially optical transmission devices for data centers, are required to be downsized in addition to demands for high speed and low power consumption. Therefore, miniaturization is also required for the optical transceiver incorporated in the optical transmission apparatus.

  At present, an optical transceiver that intervenes in a 40 Gbps or 100 Gbps high-capacity optical communication network that also supports the WDM transmission system is a standard called CFP (C form-factor pluggable, length 144.75 × width 82 × height 13.6 mm) Things are prevalent. This CFP standard optical transceiver is larger in size than a small optical transceiver compatible with a small capacity of 10 Gbps. Therefore, it is difficult to replace a conventional small-capacity optical transmission optical transceiver with a large-capacity CFP standard optical transceiver in a data center or the like.

  Therefore, development of a new standard optical transceiver that replaces CFP is progressing as a large-capacity and small-sized optical transceiver. Specifically, as described in Non-Patent Document 1 above, QSFP + (Quad Small Form-factor Pluggable Plus, length 72.4 × width 18.35 × height that can be mounted at a density four times higher than that of CFP) Development of new standard compact optical transceivers such as 8.5mm) and CFP4 (length 92 x width 21.5 x height 9.5mm) is in progress. These new standard optical transceivers are all reduced in length, width and height as compared to conventional CFP standard optical transceivers. In particular, the width is greatly reduced with respect to the length and height, and is about 1/4 with respect to 82 mm of the CFP standard.

  By the way, in response to a small new standard optical transceiver, the optical multiplexer / demultiplexer incorporated in the optical transceiver is also required to be downsized. In particular, it is required to reduce the size in the width direction. However, in the conventional optical multiplexer / demultiplexer described in Patent Document 1, an optical input / output unit such as an optical fiber collimator is arranged on a straight line as shown in FIG. Also, the input / output direction of monochromatic light (symbols L1 to L4) in the light input / output unit (FIG. 1, reference C1 to C4) for inputting / outputting monochromatic light, and the optical input / output unit for inputting / outputting multiplexed light ( In FIG. 1, the light input / output direction (symbol L5 or L18 in FIG. 1) intersects with each other at a predetermined angle (symbol 2θ in FIG. 1). Therefore, the conventional optical multiplexer / demultiplexer has a large size corresponding to the width direction of the optical transceiver, and is difficult to be incorporated in the new standard optical transceiver.

  Therefore, an object of the present invention is to provide a small optical multiplexer / demultiplexer that can be incorporated into a small optical transceiver, and an optical transceiver including the optical multiplexer / demultiplexer.

The present invention for achieving the above object is an optical multiplexer / demultiplexer that multiplexes or demultiplexes n types of light having different wavelengths, where n is a natural number,
First to nth demultiplexed light input / output units for inputting / outputting light of different single wavelengths, with the light entrance / exit as the light input / output unit,
One combined light input / output unit for inputting / outputting light obtained by combining the n types of light having different wavelengths;
Second to nth interference film filters corresponding to each of the second to nth demultiplexed light input / output units;
First to n-1 th mirrors corresponding to each of the first to n-1 demultiplexed light input / output units;
Have
The traveling direction of the light output from the first to nth demultiplexed light input / output units is defined as the front-rear direction.
The second to n-th interference film filters are disposed in front of the corresponding demultiplexed light input / output units, and selectively receive light of a single wavelength input / output to / from the corresponding demultiplexed light input / output units. Transmit and reflect light of other wavelengths,
The first to n-th demultiplexed light input / output units are two-dimensionally arranged on the same plane with the front-rear direction as a normal line when viewed from the rear,
A first mirror is disposed on the optical path of the input / output light of the first demultiplexed light input / output unit;
The kth interference film filter and the kth mirror are arranged in this order from the rear to the front on the optical path of the input / output light of the kth demultiplexed light input / output unit, where k is a natural number of 2 to n-1. And
The first mirror is disposed so as to reflect the light output forward from the first demultiplexed light input / output unit toward the second interference film filter,
The kth mirror is arranged so as to reflect the light output forward from the kth demultiplexed light input / output unit and transmitted through the kth interference film filter in the direction of the (k + 1) th interference film filter,
The kth interference film filter is arranged to reflect the light incident from the k-1th mirror toward the front,
The combined light input / output unit is disposed on the optical path of light output forward from the nth demultiplexed light input / output unit and transmitted through the nth interference film filter,
The light output from the first demultiplexed light input / output unit is input to the multiplexed light input / output unit by alternately following the first to n-1 th mirrors and the second to n th interference film filters in ascending order,
m is a natural number of 2 to n,
The m-th interference film filter transmits light having a single wavelength from light traveling from the front to the rear and inputs the light to the m-th demultiplexed light input / output unit, and transmits light having a wavelength other than the single wavelength to the m-th wavelength. Arranged to reflect toward one mirror,
The light output from the multiplexed light input / output unit alternately follows the 2nd to nth interference film filters and the 1st to n-1 mirrors in descending order, and the mth demultiplexed light in the mth interference film filter. The light input to the input / output unit and the light reflected by the first mirror are input to the first demultiplexed light input / output unit.
The optical multiplexer / demultiplexer is characterized by this.

  A first interference film filter that selectively transmits light of a single wavelength input and output by the first light input / output unit is disposed in front of the first demultiplexed light input / output unit, and the first interference An optical multiplexer / demultiplexer in which the first mirror is arranged in front of the membrane filter can also be used.

  The first to n-th light input / output units are arranged at positions that form an apex of an n-gon on the same plane, and are arranged in order in a direction that circulates the n-gon in one direction in ascending order. It may be an optical multiplexer / demultiplexer.

Alternatively, the surface on which the first to nth demultiplexed light input / output units are arranged is defined as an xy plane,
The first to n-th demultiplexed light input / output units are arranged so as to form a plurality of rows parallel to the y-axis direction with the x-axis direction light as the row direction, and are arranged in the first row. From the light input / output unit of 1 as a starting point, it is arranged in order in the ascending order of conflict,
In the last row where the nth demultiplexed light input / output unit is arranged, there are arranged demultiplexed light input / output units equal to or less than the number of demultiplexed light input / output units arranged in rows other than the last row, and An optical multiplexer / demultiplexer in which a plurality of demultiplexed light input / output units of the same number are arranged in each row other than the last row may be used.

Further, the demultiplexed light input / output unit is an even number of n ≧ 4, and is arranged in the first row and the second row,
The first to n / 2nd demultiplexed light input / output units are arranged in the first row,
The n / 2 + 1 to nth demultiplexed light input / output units are arranged in the second row,
The interference film filter and the mirror may be an optical multiplexer / demultiplexer fixed to the upper surface and the lower surface of a substrate disposed between rows.

The m-1st mirror and the mth interference film filter disposed on the same plane parallel to the zx plane with the front-rear direction as the z-axis direction are fixed on the same auxiliary substrate stacked on the substrate. ,
The auxiliary substrate is configured to be rotatable around the y-axis and is fixed at a predetermined rotational position.
An optical multiplexer / demultiplexer may be used.
The substrate includes a fixed plate having a plane parallel to the yz plane, and the m-1st mirror and the mth interference film filter arranged across the rows have side surfaces parallel to the yz plane, An optical multiplexer / demultiplexer whose side surfaces are fixed to the fixed plate can also be used.

  The demultiplexed light input / output unit is disposed at an emission position of light that passes through the corresponding interference film filter from the front to the rear, and the combined light input / output unit transmits light through the nth interference film filter from the rear to the front. It is also possible to use an optical multiplexer / demultiplexer arranged on the optical path. The mirror and / or interference film filter may be an optical multiplexer / demultiplexer in which the back surface facing the light incident surface is a reflective surface.

  The combined light input / output unit is disposed inside a region where the first to nth light input / output units are disposed as viewed from the rear, and the nth interference film filter and the combined light input / output An optical multiplexer / demultiplexer including an optical path deflecting unit that forms a bent optical path with the unit can also be provided. Further, the multiplexed light input / output unit has a light input / output port at a front end, and the optical path deflecting unit is an optical multiplexer / demultiplexer that folds back the light output from the nth light input / output unit. You can also.

  The scope of the present invention also includes an optical transceiver in which two optical multiplexers / demultiplexers are housed in a housing, one optical multiplexer / demultiplexer being an optical multiplexer and the other optical multiplexer / demultiplexer being an optical demultiplexer. The optical transceiver is an optical transceiver characterized in that at least one of the two optical multiplexers / demultiplexers is the optical multiplexer / demultiplexer described above.

  The optical multiplexer / demultiplexer according to the present invention can achieve downsizing and can be incorporated into a small optical transceiver. Other effects will be clarified in the following description.

It is a figure which shows the structure of the common optical multiplexer / demultiplexer using an interference film filter. It is a figure which shows the outline of the optical system of the optical multiplexer / demultiplexer which concerns on 1st Example of this invention. It is a figure which shows the structure of the optical multiplexer / demultiplexer which concerns on a 1st Example. It is a figure which shows the structure of the optical multiplexer / demultiplexer which concerns on the 2nd Example of this invention. It is a figure which shows the structure of the optical multiplexer / demultiplexer which concerns on the 3rd Example of this invention. It is a figure which shows the structure of the optical multiplexer / demultiplexer which concerns on the 4th Example of this invention. It is a figure which shows the 1st modification of the optical multiplexer / demultiplexer which concerns on the 4th Example of this invention. It is a figure which shows the 2nd modification of the optical multiplexer / demultiplexer which concerns on the 4th Example of this invention. It is a figure which shows the 3rd modification of the optical multiplexer / demultiplexer which concerns on the 4th Example of this invention. It is a figure which shows the modification of the optical multiplexer / demultiplexer which concerns on the 5th Example of this invention. It is a figure which shows the optical multiplexer / demultiplexer which concerns on the other Example of this invention. It is a figure which shows the optical multiplexer / demultiplexer which concerns on the other Example of this invention. It is the schematic which shows the structure of the optical transceiver based on the Example of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that in the drawings used for the following description, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted. In some drawings, reference numerals may be assigned to parts that are not required in other drawings if unnecessary.

=== Example ===
As described above, a general optical multiplexer / demultiplexer using an interference film filter is difficult to be incorporated in a new standard optical transceiver having a narrow width. Therefore, the optical multiplexer / demultiplexer according to the embodiment of the present invention has a feature in the arrangement of the optical input / output units, and can reduce the size in the width direction that is the arrangement direction of the optical input / output units. As a result, it can be easily incorporated into a new standard optical transceiver. An optical multiplexer / demultiplexer according to an embodiment of the present invention will be described below.

=== First Embodiment ===
FIG. 2 is a perspective view showing an optical system of the optical multiplexer / demultiplexer 1a according to the first embodiment of the present invention. FIG. 2 also shows an optical path when the optical multiplexer / demultiplexer 1a operates as an optical multiplexer. In the optical multiplexer / demultiplexer 1a according to the first embodiment, four demultiplexing collimators C1 serving as light input / output units for the respective monochromatic lights of the _four wavelengths λ ₁ , λ ₂ , λ ₃ , and λ _4. To C4 and one multiplexing collimator C5, and corresponding to each of the three mirrors M1 to M3 and the demultiplexing collimators C1 to C4 as optical components constituting the optical system, the wavelengths λ ₁ , λ ₂ , Four interference film filters F1 to F4 that selectively transmit monochromatic light of λ ₃ and λ ₄ are provided. Here, the traveling directions of the monochromatic lights L1 to L4 input to and output from the demultiplexing collimators C1 to C4 are defined as the front-rear direction, and the four demultiplexing collimators C1 to C4 have an opening end at the front end to define the front and rear directions. I decided to. The right-handed xyz coordinate system is defined with the direction from the rear to the front as the positive direction of the z-axis.

  The open ends of the four demultiplexing collimators C1 to C4 are two-dimensionally arranged on the same xy plane, and in this example, are arranged at the vertices of the rectangle SQ formed in the same plane. Here, when the rectangle SQ is viewed from the rear to the front, the direction in which the demultiplexing collimators C1 and C2 and the demultiplexing collimators C4 and C3 are arranged is the x-axis direction, and the demultiplexing collimators C1 and C4, and The direction in which the demultiplexing collimators C2 and C3 are arranged is the y-axis direction. The x-axis direction is the left-right direction, and the y-axis direction is the up-down direction. With respect to the left, right, up and down directions, as shown in the figure, the direction from the right to the left is the positive direction of the x axis, and the direction from the bottom to the top is the positive direction of the y axis. In addition, also in each embodiment described below including the first embodiment, the above-described coordinate system and front / rear / up / down / left / right directions are adopted. Further, the origin of the coordinate system is not particularly defined, and the surfaces parallel to the xy plane, the yz plane, and the zx plane are all referred to as an xy plane, a yz plane, and a zx plane. Further, the demultiplexing collimators C1 to C4 and the multiplexing collimator C5 are assumed to have an optical axis in the z-axis direction.

As shown in FIG. 2, in front of the branching collimator C1 -C4, an interference film filter F1~F4 that selectively transmits a wavelength lambda ₁ to [lambda] _4, respectively are arranged, the demultiplexing collimator C1~C3 Mirrors M1 to M3 are further arranged in front of the corresponding interference film filters F1 to F3. A multiplexing collimator C5 is disposed in front of the interference film filter F4.

Here, the arrangement of the demultiplexing collimators C1 to C4, the combining collimator C5, and the optical components constituting the optical system will be described based on the optical paths shown in the drawing. The mirror M1 is directed forward from the demultiplexing collimator C1. The light L11 emitted and transmitted through the interference film filter F1 is arranged to reflect in the direction of the interference film filter F2. Note monochromatic light L1 demultiplexing collimator C1 is input and output, if has a very sharp wavelength characteristics at a single wavelength lambda _1, the interference film filter F1 is not an essential component.

The interference film filter F2 reflects the light L12 incident from the mirror M1 forward along the z-axis. The reflected light L13 enters the mirror M2. Monochromatic light L1 having a wavelength lambda ₁ from demultiplexed collimator C1 by which traces the light path of the same zx plane a (L11 to L13), the mirror M1, in being successively reflected interference film filter F2 reaches the mirror M2. The monochromatic light L2 having the wavelength λ ₂ from the demultiplexing collimator C2 is combined with the light L12 incident on the interference film filter F2 from the mirror M1 when passing through the interference film filter F2, and has wavelengths λ ₁ and λ _2. Each of the monochromatic lights travels in the direction of the mirror M2 as the combined light.

The mirror M2 is disposed so as to reflect the light incident forward along the z axis toward the lower side in the yz plane, and the collimator C3 in which the reflected light L14 from the mirror M2 is disposed below the collimator C2. Is incident on an interference film filter F3 disposed in front of. Interference film filter F3, as well reflects toward the front along the optical L14 incident from mirror M2 to the z-axis, and transmits the monochromatic light L3 having a wavelength lambda ₃ from the demultiplexing collimator C3. Thereby, the transmitted light from the rear in the interference film filter F3 and the incident light L14 from the front are combined, and the light L15 including each monochromatic light of the wavelengths λ _{1 to} λ ₃ is directed to the mirror M3.

The mirror M3 is arranged so as to reflect the light L15 incident forward from the interference film filter F3 in the direction of the interference film filter F4. The interference film filter F4 reflects the multiplexed light L16 of the light having the wavelengths λ _{1 to} λ ₃ incident from the mirror M3 forward along the z axis and is monochromatic with the wavelength λ ₄ from the demultiplexing collimator C4. The light L4 is transmitted. Whereby multiplexed optical L17 having a wavelength lambda ₁ to [lambda] ₄ and the light L16 including monochromatic light L4 and the wavelength lambda ₁ to [lambda] ₃ wavelength lambda ₄ is multiplexed is directed forward along the z-axis. The light L17 from the interference film filter F4 is input to the multiplexing collimator C5, and this light L17 is output as an output light from the optical multiplexer / demultiplexer 1a via the optical fiber Fb5 connected to the front end of the multiplexing collimator C5. Sent to the communication network. In the optical multiplexer / demultiplexer 1a including the optical system described above, when the monochromatic light L1 emitted forward from the demultiplexing collimator C1 is viewed from the rear, the rectangular regions SQ described above from the demultiplexing collimators C1 to C4. Are combined with the monochromatic lights L2 to L4 of other wavelengths while following a U-shaped optical path that borders the outline of the light in the clockwise direction. When the optical multiplexer / demultiplexer 1a operates as an optical demultiplexer, the multiplexed light L5 combined with all the wavelengths λ _{1 to} λ ₄ is emitted backward from the collimator C5, and then the optical paths L11 to L11. Trace L17 in reverse order in descending order. In the interference film filters F4, F3, F2, and F1, light traveling from the front to the rear along the z-axis corresponding to the lights L17, L15, L13, and L11, respectively, along the optical path that follows in the opposite direction. Incident. Interference film filters F4, F3, F2, and F1 transmit monochromatic light of wavelengths λ ₄ , λ ₃ , λ ₂ , and λ ₁ , respectively, and input the transmitted light to collimators C4, C3, C2, and C1 Let

  Next, a more specific configuration of the optical multiplexer / demultiplexer 1a according to the first embodiment will be described. FIG. 3 is a diagram showing the configuration of the optical multiplexer / demultiplexer 1a according to the first embodiment. FIGS. 3 (A), (B), (C), and (D) are respectively the optical multiplexer / demultiplexers. The rear view when 1a is seen from back, the top view when it sees from the upper part, the side view when it sees from the right side, and the top view when it sees from the bottom are shown. Here, the optical path when the optical multiplexer / demultiplexer 1a is operating as an optical multiplexer is shown.

  The interference film filters F1 to F4 and the mirrors M1 to M3 constituting the optical system of the optical multiplexer / demultiplexer 1a according to the first embodiment are arranged on the upper and lower surfaces (11, 12) of the flat substrate 10 having the xz plane. Has been. On the upper surface 11 side, interference film filters F1 and F2 and mirrors M1 and M2 are arranged in a fixed state. Further, the demultiplexing collimators C1 and C2 are also arranged on the upper surface side of the substrate 10 in a state of being fixed by an appropriate holding structure not shown. On the lower surface 12 side, demultiplexing collimators C3 and C4, a multiplexing collimator C5, interference film filters F3 and F4, and a mirror M3 are arranged in a fixed state. The demultiplexing collimators C1 to C4 have a front end as an opening end, and the multiplexing collimator C5 has a rear end as an opening end. These open ends serve as an optical input / output unit in the optical multiplexer / demultiplexer 1a. A rectangular notch 13 is formed on the right end side of the substrate 10 to connect the upper and lower surfaces (11-12) to pass the optical path in the yz plane formed between the mirror M2 and the interference film filter F3. Has been.

  As shown in FIG. 3B, the interference film filter F1 has a light incident / exit surface on the xy plane, and the reflection surface of the mirror M1 is opposite to the xy plane around the y axis when viewed from above. It is tilted while being rotated clockwise at an angle θ. That is, the light L11 is incident on the mirror M1 at an incident angle θ. The light incident / exit surface in the interference film filter F2 is directed from the upper side to the lower side and is inclined in the counterclockwise direction about the y axis at an angle θ so as to face the mirror M1.

That is, the light incident / exit surface of the interference film filter F2 is inclined at an angle θ in the counterclockwise direction around the y axis with respect to the optical axis of the demultiplexing collimator C2. Thereby, the light L12 from the mirror M1 enters the interference film filter F2 at an incident angle θ. The angle θ is set based on the distance D in the front-rear direction between the mirror M2 and the interference filter F2 on the substrate upper surface 11 and the distance P in the left-right direction between the demultiplexing collimators C1 and C2 on the substrate upper surface 11.

  As shown in FIG. 3 (C), the reflecting surface of the mirror M2 is seen from the right to the left, and the xy plane is counterclockwise around the x axis so that the normal direction is directed downward and forward. It faces in a direction tilted at an angle φ. As a result, the light L13 incident on the mirror M2 travels in the direction of the interference film filter F3 disposed on the lower surface 12 of the substrate 10 via the notch 13 formed in the substrate 10. The angle φ is based on the distance D in the front-rear direction between the mirror M2 and the interference filter F2 on the substrate upper surface 11 and the distance Ph in the vertical direction between the demultiplexing collimator C2 on the substrate upper surface 11 and the demultiplexing collimator C3 on the substrate lower surface 12. Is set. The light incident / exit surface in the interference film filter F3 is counterclockwise about the x axis so that the light incident / exit surface faces the mirror M2 disposed on the upper surface 11 of the substrate 10 when viewed from the right side. It faces the direction tilted at an angle φ. Therefore, the angle formed between the light L14 directed from the substrate upper surface 11 through the notch 13 to the substrate lower surface 12 and the optical axis of the demultiplexing collimator C3 is 2φ as shown in the figure.

  As shown in FIG. 3D, the reflecting surface of the mirror M3 disposed on the substrate lower surface 12 is a direction in which the xy plane is inclined counterclockwise about the y axis at an angle θ when viewed from the lower side to the upper side. Suitable for. That is, the light L15 from the interference film filter F3 is incident on the mirror M3 at an incident angle θ. Then, the light incident / exit surface of the interference film filter F4 is oriented in a direction in which the xy plane is tilted counterclockwise around the y axis at an angle θ so as to face the mirror M3 when viewed from below. That is, the light L16 from the mirror M3 enters the interference film filter F4 at an incident angle θ. Therefore, the light L16 incident on the interference film filter F4 is reflected forward along the z-axis direction. A multiplexing collimator C5 is disposed on the optical path of the reflected light L17. In the optical multiplexer / demultiplexer 1a according to the first embodiment, the demultiplexing collimators C1 to C4, the interference film filters F1 to F4, the mirrors M1 to M3, and the multiplexing collimator C5 are arranged as described above. As shown in FIG. 3A, the optical path L when the optical multiplexer / demultiplexer 1a is viewed from behind is formed so that the positions of the demultiplexing collimators C1 to C4 follow the U-shape in this order.

  In the optical multiplexer / demultiplexer 1a configured as described above, the interference film filters F2 to F4 are arranged to be inclined with respect to the optical axes of the corresponding demultiplexing collimators C2 to C4. If the film surface is greatly inclined with respect to the light transmission direction, the light intensity of the P wave and the S wave that vibrate in directions orthogonal to each other in the light transmission process is different, that is, the insertion loss is polarization dependent. Occurs. In addition, polarization mode dispersion in which a difference in propagation speed between the P wave and the S wave occurs. As for the mirror, if the reflection film is a dielectric film, the reflectance has wavelength dependency and angle dependency. In the present embodiment, θ ≦ 15 ° and φ ≦ 15 ° are set in consideration of the above-described various dependencies.

Next, the wavelength of the light demultiplexed and combined by the optical multiplexer / demultiplexer 1a according to the first embodiment, the specific size and angle of each part in the optical multiplexer / demultiplexer 1a, and the like will be described. First, the wavelengths of monochromatic light input and output by the demultiplexing collimators C1, C2, C3, and C4 are λ ₁ = 1271 nm, λ ₂ = 1291 nm, λ ₃ = 1131 nm, and λ ₄ = 1331 nm, respectively. The distance P between the branching collimators (C1-C2, C3-C4) in the left-right direction is P = 4 mm.

  The interference film surfaces in the interference film filters F1 to F4 and the reflection surfaces of the mirrors M1 to M3 have a rectangular shape of w1.4 mm × h1.4 mm, and have a refractive index n = 1.5 and a thickness t = 1 mm, respectively. An interference film surface and a reflection surface are formed on the surface of the film. The interference film surface and the reflection surface are so thin that they can be ignored with respect to the thickness t of the transparent substrate. The center distance D in the front-rear direction between the position where the interference film filters F1 to F4 are arranged and the position where the mirrors M1 to M3 are arranged is about 8.5 mm. Accordingly, the angle θ is set to θ = 13.5 ° from the distance P and the center-to-center distance D. Of course, P and D may be set after setting θ. The vertical distance Ph of the branching collimator is set to an angle φ = θ = 13.5 ° so that P = Ph, and Ph = P = 4 mm. As described above, the optical multiplexer / demultiplexer 1a according to the first embodiment has a size that can be sufficiently incorporated into the optical transceiver of the QSFP + or CFP4 standard described above. It is also possible to incorporate two optical multiplexers / demultiplexers 1a in parallel in the left and right in the optical transceiver corresponding to each of the optical demultiplexer and the optical multiplexer.

=== Second Embodiment ===
The interference film filter has a structure in which an interference film is formed on the surface of the transparent substrate, and light incident obliquely to the interference film surface of the interference film filter is incident on the xy plane of the incident light and the emitted light depending on the refractive index of the transparent substrate. Is out of position. That is, the optical path of light passing through the interference film filter is shifted before and after the transmission. Therefore, in the optical multiplexer / demultiplexer according to the second embodiment, the demultiplexing collimator and the multiplexing collimator are arranged at positions that take into account the shift of the optical path.

  FIG. 4 shows the arrangement of optical components in the optical multiplexer / demultiplexer 1b according to the second embodiment of the present invention. 4A is a plan view when the optical multiplexer / demultiplexer 1b according to the second embodiment is viewed from above, and FIG. 4B is a side view when the optical multiplexer / demultiplexer 1b is viewed from the right side. FIG. FIG. 4C is a plan view of the optical multiplexer / demultiplexer 1b as viewed from below. As shown in FIG. 4A, in the optical multiplexer / demultiplexer 1b according to the second embodiment, the interference film filter F1 corresponding to the demultiplexing collimator C1 is omitted, but other basic structures are omitted. In addition, the optical components constituting the optical system are the same as those in the first embodiment shown in FIG. Further, the optical multiplexer / demultiplexer 1b shown in FIG. 4 operates as an optical multiplexer.

The arrangement of the demultiplexing collimators C1 to C4 and the multiplexing collimator 5 in the optical multiplexer / demultiplexer 1b according to the second embodiment will be described below. First, as shown in FIG. 4A, the demultiplexing collimators C1 and C2 arranged on the upper surface 11 of the substrate 10 are arranged at a distance P. Although each of the demultiplexing collimator C1, C2 monochromatic light L1 having a wavelength lambda ₁ and lambda ₂ from the L2 is incident monochromatic light L2 incident on the interference film filter F2 is refracted at the transparent substrate, an interference film filter It shifts by a distance ΔP corresponding to the refractive index and thickness t of the transparent substrate before and after passing through F2. Therefore, the mirror M1 and the interference film filter F2 are disposed so that the light L12 from the mirror M1 toward the interference film filter F2 is incident on the emission position of the monochromatic light L2 in the interference film filter F2. The distance in the left-right direction between the light L11 traveling from the demultiplexing collimator C1 to the mirror M1 and the light L13 traveling from the interference film filter F2 to the mirror M2 is P−ΔP.

  Next, the light L13 from the interference film filter F2 toward the mirror M2 is reflected by the mirror M2 and enters the interference film filter F3. As shown in FIG. 4B, the light entrance / exit surface of the interference film filter F3 rotates around the x axis with respect to the optical axis of the corresponding demultiplexing collimator C3, but around the y axis. It is not rotating. Therefore, the monochromatic light L3 incident on the interference film filter F3 from the demultiplexing collimator C3 does not shift in the x-axis direction before and after transmission through the interference film filter F3. However, since the light incident / exit surface of the interference film filter F3 is tilted in a state of being rotated about the x axis, the monochromatic light L3 emitted from the demultiplexing collimator C3 is transmitted in the y axis direction before and after passing through the interference film filter F3. Shift upward. If the mirror M2 on the upper surface 11 of the substrate is tilted at an angle θ around the x axis with respect to the optical axis of the demultiplexing collimator C2, the interference film filter F3 is also in the optical axis of the demultiplexing collimator C3 on the lower surface 12 of the substrate. It is inclined at an angle θ. Therefore, the monochromatic light L3 input from the demultiplexing collimator C3 is shifted upward by ΔP before and after passing through the interference film filter F3. Further, since the reflecting surface of the mirror M3 is not inclined around the x axis, the lights L16 and L17 that subsequently reach the multiplexing collimator C5 via the interference film filter F4 do not shift in the vertical direction. Therefore, the distance between the demultiplexing collimators C1 and C4 on the upper surface 11 and the lower surface 12 of the substrate 10 is set to P−ΔP, and the distance between the demultiplexing collimators C2 and C3 is set to P.

  As shown in FIG. 4C, when viewed from below from above, the reflecting surface of the mirror M3 is inclined in the direction by rotating the xy plane counterclockwise around the y axis at an angle θ. In addition, the light incident / exit surface of the interference film filter F4 is inclined in a direction in which the xy plane is rotated counterclockwise by an angle θ around the y axis when viewed from below. The light L17 from the interference film filter F4 toward the multiplexing collimator C5 is parallel to the optical axis of the demultiplexing collimator C4. Therefore, similarly to the case where the monochromatic light L2 is transmitted through the interference film filter F2 on the upper surface 11 of the substrate, the monochromatic light L4 emitted from the branching collimator C4 is shifted to the left by the distance ΔP. That is, the demultiplexing collimators C3 and C4 that are separated from each other by the distance P in the left-right direction on the substrate lower surface 12 are arranged at positions shifted by ΔP to the left with respect to the demultiplexing collimators C1 and C2 on the substrate upper surface 11, respectively. Yes.

  The distance in the left-right direction between the demultiplexing collimator C3 and the combining collimator C5 is set to P−ΔP. Specifically, the values of ΔP in the interference film filters F2 to F4 are specifically listed. The distance P between the demultiplexing collimators C1 and C2 is 4 mm, the thickness t of the transparent substrate of each of the interference film filters F2 to F3 is 1 mm, the transparent film When the refractive index n of the substrate is 1.5, ΔP is about 0.1 mm.

  As described above, in the optical system in the optical multiplexer / demultiplexer 1b according to the second embodiment of the present invention, the optical fiber collimators C1 to C5 are in the optimum positions in consideration of the shift of light transmitted through the interference film filters F1 to F4. The coupling loss of light input to each of the optical fiber collimators C1 to C5 can be reduced. Of course, when looking from the rear to the front, the demultiplexing collimators C1 to C4 are arranged at the vertices of the square with one side P, and the multiplexing collimator C5 is arranged at the same position as the demultiplexing collimator C4. The inclination angles of the reflecting surface and the light incident / exiting surfaces of the interference film filters F2 to F4 may be set individually. In any case, the optical loss can be reduced by disposing the demultiplexing collimators C1 to C4 and the combining collimator C5 at the positions considering the optical path shift in the interference film filters F2 to F4.

=== Third embodiment ===
In the optical multiplexer / demultiplexers according to the first and second embodiments, the demultiplexing collimators are arranged in two rows and two columns in the same plane when viewed from the rear, and the width in the left-right direction can be reduced. The optical multiplexer / demultiplexer according to the third embodiment has a configuration that can further reduce the size in the front-rear direction.

  FIG. 5 shows an optical multiplexer / demultiplexer according to the third embodiment. FIG. 5A is a plan view when the optical multiplexer / demultiplexer 1a according to the first embodiment shown above is viewed from above, and FIG. 5B is an optical multiplexer / demultiplexer according to the third embodiment. It is a top view when the container 1c is seen from upper direction. In the optical multiplexer / demultiplexer 1a according to the first embodiment shown in FIG. 5A, the mirrors M1 and M2 and the mirror M3 (not shown) are surfaces on the side where light is incident on the transparent substrate having a predetermined thickness. The surface reflection type mirror was formed. The interference film filters F1 and F2 and the interference film filters F3 and F4 (not shown) were also of the surface reflection type. That is, the surface on which the interference film is formed on the transparent substrate is the reflection surface R, and the reflection surface R is the surface on the side where the reflected light from the mirrors M1 to M3 is incident.

  On the other hand, in the optical multiplexer / demultiplexer 1c according to the third embodiment shown in FIG. 5B, the mirrors M1, M2, the mirror M3 (not shown), the interference film filters F1, F2, and the interference film filter (not shown). The reflection surface R of F3 and F4 is a back surface reflection type formed on the back surface side facing the light incident surface. As a result, the light incident on the mirrors M1 to M3 and the interference film filters F1 to F4 is transmitted through the transparent substrate and reflected by the reflection surface R on the back surface side. As a result, in the optical multiplexer / demultiplexer 1c according to the third embodiment, the size in the front-rear direction can be shortened with respect to the optical multiplexer / demultiplexer 1a according to the first embodiment. As described above, in the optical multiplexer / demultiplexer 1a according to the first embodiment, the center-to-center distance D is about 8.5 mm. However, the center-to-center distance in the optical multiplexer / demultiplexer 1c according to the third embodiment is as follows. d was 7.2 mm and could be shortened by about 1.3 mm. Of course, both the mirror and the interference film filter may not be the back surface reflection type, and one optical component of the mirror and the interference film filter may be the back surface reflection type.

  In the case of a back surface reflection type mirror or interference film filter, there is a possibility that light reflected on the back surface of the transparent substrate is multiple-reflected inside the transparent substrate, resulting in light loss. Therefore, when there is a concern about light loss, the front and back surfaces of the transparent substrate may not be parallel to each other, but may be shifted from a parallel state by a minute angle (for example, 0.1 °). If the front and back surfaces of the transparent substrate are shifted from the parallel state, the light incident on the transparent substrate is refracted on the same principle as in the second embodiment, and the optical path is shifted. However, if the deviation from the parallel state is a small angle, the shift of the optical path can be substantially ignored. Of course, each demultiplexer collimator may be arranged in consideration of the shift of the optical path as in the second embodiment.

=== Fourth embodiment ===
In the optical multiplexer / demultiplexer according to each of the above embodiments, the multiplexing collimator C5 is arranged at a position determined according to the positions of the demultiplexing collimators C1 to C4, the mirrors M1 to M3, and the arrangement of the interference film filters F2 to F4. It was. Further, the multiplexing collimator C5 had an open end on the rear side. Therefore, the optical multiplexer / demultiplexer according to the fourth embodiment of the present invention has a configuration in which the arrangement of the multiplexing collimator C5 can be freely set.

  FIG. 6 shows a schematic configuration of the optical multiplexer / demultiplexer according to the fourth embodiment. FIGS. 6A and 6B are plan views of the optical multiplexer / demultiplexer (1d, 1e) as viewed from below. The optical multiplexer / demultiplexer (1d, 1e) shown in FIGS. 6A and 6B bends the optical path along the optical path formed between the interference film filter F4 and the multiplexing collimator C5. An optical path deflecting unit (20a, 20b) is provided.

  In the optical multiplexer / demultiplexer 1d shown in FIG. 6A, an optical path deflecting unit 20a made of a rhombus prism is interposed in the optical path between the demultiplexing collimator C4 and the multiplexing collimator C5. Then, the light L17 directed from the interference film filter F4 toward the multiplexing collimator C5 is bent rightward and then bent forward again to form a crank-shaped optical path between the interference film filter F4 and the multiplexing collimator C5. Is done. Then, light traveling forward from an intermediate position between the optical axes of the demultiplexing collimators C3 and C4 is input to the multiplexing collimator C5. Therefore, when viewed from the rear, the multiplexing collimator C5 is disposed at an intermediate position between the demultiplexing collimators C3 and C4.

  The optical path deflecting unit 20b in the optical multiplexer / demultiplexer 1e shown in FIG. 6B is configured by a right-angle prism or an isosceles trapezoid prism with the apex of the right-angle prism flattened, and the like from the interference film filter F4 to the multiplexing collimator C5. The light L <b> 17 heading toward is folded back in the direction of the intermediate position between the demultiplexing collimators C <b> 3 and C <b> 4. Accordingly, when viewed from the rear, the multiplexing collimator C5 is arranged in the demultiplexing collimators C3 and C4, and has an opening end in the front, and is arranged in the same plane as all the demultiplexing collimators C1 to C4. ing.

  Note that by changing the arrangement of the optical path deflecting units (20a, 20b) in the optical multiplexers / demultiplexers (1d, 1e) shown in FIGS. 6 (A) and 6 (B), the multiplexing collimator C5 can be separated from the rear side. It can also be arranged at the center of a rectangular area formed by the wave collimators C1 to C4. FIG. 7 shows an optical multiplexer / demultiplexer 1f in which a multiplexing collimator C5 is arranged at the center of a rectangular area formed by the demultiplexing collimators C1 to C4 as a first modification of the fourth embodiment. Here, the state when the optical multiplexer / demultiplexer 1f operates as an optical multiplexer is also shown. 7A is a front view of the optical multiplexer / demultiplexer 1f as viewed from the front, and FIG. 7B is a side view of the optical multiplexer / demultiplexer 1f as viewed from the right. In the optical multiplexer / demultiplexer 1f shown here, a multiplexing collimator C5 having an opening end on the front end side is disposed behind the substrate 10. The opening end of the multiplexing collimator C5 is flush with the opening ends of the demultiplexing collimators C1 to C4, and is arranged at the center of the arrangement region of the demultiplexing collimators C1 to C4. The optical path deflecting unit 20c in the optical multiplexer / demultiplexer 1f is composed of a right-angle prism or an isosceles trapezoidal prism as in the optical multiplexer / demultiplexer 1e shown in FIG. 6B. However, as shown in FIG. 7A, in the optical path deflecting unit 20c, the side surface 120 of the prism having a triangular shape or an isosceles trapezoid is inclined 45 ° around the z axis with respect to the zx plane. When viewed from the front-rear direction, the light incident / exit surface of the optical path deflecting unit 20 is disposed across the opening end of the demultiplexing collimator C4 and the left-right center position of the front end surface of the substrate 10.

  As an operation of the optical path deflecting unit 20c, when the light L17 directed from the interference film filter F4 toward the multiplexing collimator C5 is incident on the rear surface, the light is bent toward the upper left and folded forward. Therefore, the optical path of the light L18 entering and exiting the optical path deflecting unit 20c is directed from the demultiplexing collimator C4 to the left and right center position of the substrate 10 when viewed from the front-rear direction. That is, the emission position in the left-right direction of L18 is the center of the arrangement region of the four demultiplexing collimators C1 to C4.

  Since the substrate 10 is interposed on the optical path of the light L18 emitted from the optical path deflecting unit 20c, as shown in FIG. 7B, in this example, the substrate 10 has a hole 14 penetrating in the front-rear direction. ing. Of course, the substrate 10 may be divided into left and right. In any case, a passage 14 through which light is transmitted by connecting the substrate 10 in the front-rear direction is provided. As a result, the light L18 emitted from the optical path deflecting unit 20c is directed to the rear end side of the substrate 10 by the light L19 passing through the passage 14. In the illustrated example, the notch 15 is formed behind the substrate 10 so that the opening end of the multiplexing collimator C5 is arranged in the same plane as the opening ends of the demultiplexing collimators C1 to C4. With the above configuration, in the optical multiplexer / demultiplexer 1f, the multiplexing collimator C5 is disposed on the rear end side, and is disposed at the center of the arrangement region of the demultiplexing collimators C1 to C4 when viewed from the front-rear direction. Thus, in the optical multiplexer / demultiplexer (1d to 1f) according to the fourth embodiment, the position of the multiplexing collimator C5 can be freely set by including the optical path deflecting units (20a to 20c). Yes.

  As a modification of the fourth embodiment, there is also an optical multiplexer / demultiplexer 1g according to the second modification shown in FIG. FIG. 8 is a diagram showing a state when the optical multiplexer / demultiplexer 1g is operating as an optical multiplexer, and FIG. 8 (A) is a front view when the optical multiplexer / demultiplexer 1g is viewed from the front. FIG. 8B is a side view of the optical multiplexer / demultiplexer 1g as viewed from the right. In the optical multiplexer / demultiplexer 1g of the second modification of the fourth embodiment, the optical path deflecting unit 20c in the optical multiplexer / demultiplexer 1f shown in FIG. 7 is changed to an optical path deflecting unit 20d using a rhombus prism. . The multiplexing collimator C5 is arranged at the center of the arrangement region of the demultiplexing collimators C1 to C4 when viewed from the front-rear direction, and the multiplexing collimator C5 is arranged on the front end side.

  Also, the optical multiplexing / demultiplexing shown in FIGS. 7 and 8 can be performed by combining the configurations of the optical path deflecting units (20a, 20b) in the optical multiplexing / demultiplexing devices (1d, 1e) shown in FIGS. An optical multiplexer / demultiplexer that operates in the same manner as the optical units (1f, 1g) can be configured. FIG. 9 shows a third modification of the fourth embodiment. Here, an optical multiplexer / demultiplexer 1h that performs the same operation as the optical multiplexer / demultiplexer 1f shown in FIG. 7 is shown. FIG. 9 is a diagram showing a state when the optical multiplexer / demultiplexer 1h is operating as an optical multiplexer, and FIG. 9 (A) is a side view when the optical multiplexer / demultiplexer 1h is viewed from the right side. FIG. 9B is a plan view of the optical multiplexer / demultiplexer 1h as viewed from below. In the optical multiplexer / demultiplexer 1h, a multiplexing collimator C5 having an opening end on the front end side is disposed behind the substrate 10. The opening end of the multiplexing collimator C5 is flush with the opening ends of the demultiplexing collimators C1 to C4, and is arranged at the center of the arrangement region of the demultiplexing collimators C1 to C4. The optical path deflecting unit 20e in the optical multiplexer / demultiplexer 1h includes a first optical path deflecting unit 21 composed of a right-angle prism or an isosceles trapezoidal prism and a second optical path deflecting unit 22 composed of a rhombus prism.

  As the operation of the optical path deflecting unit 20e, first, the first optical path deflecting unit 21 bends the light L17 directed from the interference film filter F4 to the combining collimator C5 upward and then returns to the front. Therefore, the optical path of the light L18 entering and exiting the first optical path deflecting unit 21 is bent in a U shape when viewed from the left-right direction. The emission position of the light L18 is an intermediate position between the demultiplexing collimators C2 and C3. When the light L18 folded forward by the first optical path deflecting unit 21 enters the second optical path deflecting unit 22, the second optical path deflecting unit 22 shifts the incident light L18 to the right and moves forward. And exit. The optical path of the light L19 that enters and exits the second optical path deflecting unit 22 is bent in a crank shape when viewed from the up and down direction. Further, the emission position of the light L19 in the left-right direction is an intermediate position between the demultiplexing collimators C2 and C3. Therefore, the position where the light L19 is emitted from the second optical path deflecting unit 22 is the center of the arrangement region of the four demultiplexing collimators C1 to C4 when viewed from the front-rear direction. Also in this optical multiplexer / demultiplexer 1h, as shown in FIG. 8A, there is provided a passage 14 through which light passes through the substrate 10 in the front-rear direction. In the third modification, for example, if the second optical path deflecting unit 22 is a right-angle prism or an isosceles trapezoidal prism, the light L18 folded back by the first optical path deflecting unit 21 is folded back forward again. Thus, an optical multiplexer / demultiplexer that operates in the same manner as the optical multiplexer / demultiplexer 1g shown in FIG. 8 can be configured.

  As described above, the optical multiplexer / demultiplexer (1d to 1h) according to the fourth embodiment includes the optical path deflecting units (20a to 20e), so that the position of the multiplexing collimator C5 can be freely set. Yes. The optical path deflecting units (20a to 20e) in the optical multiplexers / demultiplexers (1d to 1h) shown in FIGS. 6 to 9 form a bent optical path using a prism, but the optical path is bent in the prism. You may comprise a surface with a mirror.

=== Fifth embodiment ===
In an optical multiplexer / demultiplexer using an interference film filter, it is necessary to accurately guide the input light to the position of the demultiplexing collimator or the opening end of the multiplexing collimator to reduce the optical loss as much as possible. That is, high alignment accuracy is required. In order to increase the alignment accuracy, it is necessary to fix the interference film filter and the mirror in a state of being aligned with high accuracy. In particular, the optical multiplexer / demultiplexer 1b according to the second embodiment has a configuration in consideration of the optical path shift in the interference film filters F1 to F4, and higher alignment accuracy is required. Therefore, the optical multiplexer / demultiplexer according to the fifth embodiment of the present invention includes a configuration and a structure that improve the alignment accuracy and facilitate the alignment operation.

  FIG. 10 shows an optical multiplexer / demultiplexer 1i according to the fifth embodiment. FIG. 10A shows a perspective view when the optical multiplexer / demultiplexer 1i is viewed from the upper left rear, and FIG. 10B shows a perspective view when the optical multiplexer / demultiplexer 1i is viewed from the lower left rear. ing. The optical system of the optical multiplexer / demultiplexer 1i is the same as the optical multiplexer / demultiplexer 1b according to the second embodiment shown in FIG.

  As shown in FIGS. 10A and 10B, the substrate 10 is integrally formed with flat portions having front and rear surfaces parallel to the xy plane at both front and rear ends. It has a letter shape. The front and rear plate-like portions of the H-shaped substrate 10 are collimator holding portions (16 and 17) for holding the demultiplexing collimators C1 to C4 and the combining collimator C5, and the rear collimator holding portions. 16 are formed with four holes 18 penetrating in the front-rear direction at equal intervals in the left-right and up-down directions. The front end portions of the demultiplexing collimators C1 to C4 are inserted into the holes 18, respectively. Yes. As shown in FIG. 10B, the front collimator holding portion 17 has a hole 19 penetrating in the front-rear direction, and the rear end portion of the combining collimator C5 is inserted into the hole 19. The The demultiplexing collimators C1 to C4 and the combining collimator C5 are fixed to the collimator holding portions (16, 17) by welding, bonding, or the like.

  As shown in FIG. 10A, in the optical system of the optical multiplexer / demultiplexer 1i, the mirror M1 and the interference film filter F2 face each other and rotate around the y-axis with respect to the z-axis direction. M1 and the interference film filter F2 are fixed to the upper surface of the auxiliary substrate 30 different from the substrate 10 while maintaining the relationship of facing each other. The auxiliary substrate 30 is laminated on the upper surface 11 of the substrate 10. A hole 31 penetrating in the vertical direction is formed in the auxiliary substrate 30, and a flat cylindrical protrusion 32 that engages with the hole 31 is formed on the upper surface 11 of the substrate 10. The central axis 33 of the protrusion 32 is parallel to the y-axis, and the auxiliary substrate 30 is rotated around the central axis 33 when performing alignment work. When the alignment work is finished, the auxiliary substrate 30 is fixed to the substrate 10 by a method such as welding or adhesion. Accordingly, the reflecting surface of the mirror M1 and the light incident / exiting surface of the interference film filter F2 are fixed in a state where the xy plane is rotated around the y axis at a predetermined angle while facing each other.

  As shown in FIG. 10B, the lower surface 12 of the substrate 10 is also provided with a mirror M3 and an interference film filter F4 in which the xy plane is inclined by a predetermined angle around the y axis while facing each other. . The mirror M3 and the interference film filter F4 are fixed to the lower surface of the auxiliary substrate 40 laminated on the lower surface 12 of the substrate 10. Further, a hole 41 penetrating in the vertical direction is also formed in the auxiliary substrate 40, and a flat cylindrical protrusion 42 that engages with the hole 41 is formed on the lower surface 12 of the substrate 10. Similar to the auxiliary substrate 30 on the upper surface 12 side of the substrate 10, the auxiliary substrate 40 is rotatable with respect to the substrate 10 around the axis 43 of the protrusion 42 during the alignment operation. After the alignment operation, the auxiliary substrate 40 is fixed to the substrate 10 while being adjusted to a predetermined rotational position.

  In the optical multiplexer / demultiplexer 1 i, the fixed plate 50 having the yz plane is disposed in front of the upper surface 11 and the rear surface of the lower surface 12 of the substrate 10, and the right end surface of the mirror M <b> 2 or the interference film filter F <b> 3 is the left surface of the fixed plate 50. It is glued to. Thereby, the mirror M2 and the interference film filter F3 are fixed in a state inclined at a predetermined angle around the x axis. Further, in this example, the fixed plate 50 is formed of an integral flat plate whose upper end side and lower end side are connected via the notch portion 13, and the region connecting the upper end side and the lower end side is the right end of the notch portion 13. It is fitted on the side.

=== Other Embodiments ===
In the above-described embodiment, an optical multiplexer / demultiplexer that performs multiplexing and demultiplexing of four different types of monochromatic light is illustrated. However, each of the above embodiments is applied to an optical multiplexer / demultiplexer that inputs / outputs light of more wavelengths. You can also. For example, like the optical multiplexer / demultiplexer 1j shown in FIG. 11, a plurality of demultiplexing collimators C11 to C18 may be arranged at the positions of the polygonal vertices when viewed from the rear. In the illustrated example, eight demultiplexing collimators C11 to C18 are arranged on the same xy plane so as to form a regular octagonal apex. An interference film filter (not shown) is disposed at least on the front end side of each of the demultiplexing collimators C11 to C18 other than the demultiplexing collimator C11, and a mirror (not illustrated) is disposed in front of the demultiplexing collimator C11 and each interference film filter. Yes. Then, the input light traveling forward from the demultiplexing collimator C1 which is the starting point of the optical path is sequentially reflected by the mirrors arranged on the optical axes of the demultiplexing collimators C11 to C18 and the interference film filter, and forward from the rear. , The optical path L of light that repeats these reflections is formed so as to go around the polygon in one direction.

  Alternatively, as in the optical multiplexer / demultiplexer 1k illustrated in FIG. 12, when the front is viewed from behind, a plurality of demultiplexing collimators C21 to C29 may be arranged in three or more rows. Then, the optical path L that is sequentially reflected between the mirror and the interference film filter starting from the demultiplexing collimator C1 and reaches the multiplexing collimator is formed so as to have a twisted shape when viewed from behind. Also good. Depending on the number of branching collimators, the same number of branching collimators cannot be arranged in all rows. In that case, the same number of branching collimators may be arranged in rows other than the bottom row.

  In the optical multiplexer / demultiplexer in each of the embodiments described above, the opening end of the optical fiber collimator is used as the light input / output unit that is the entrance / exit of light from the outside. However, the optical input / output unit may have any form. . For example, a form in which laser light propagating in space is directly input to and output from the optical system may be used. Of course, the optical fiber connected to the demultiplexing collimators C1 to C4 and the multiplexing collimator C5 may be further connected to another optical fiber via an optical connector or the like.

  The optical multiplexer / demultiplexer according to the embodiment of the present invention can reduce the area of the region where the collimator is arranged, and can be applied to a new standard optical transceiver such as QSFP + or CFP4. In the embodiment of the present invention, two optical multiplexers / demultiplexers are provided, one optical multiplexer / demultiplexer operates as an optical multiplexer, and the other optical multiplexer / demultiplexer operates as an optical demultiplexer. In the optical transceiver, at least one of the two optical multiplexers / demultiplexers is the optical multiplexer / demultiplexer according to the embodiment of the present invention.

  FIG. 13 shows the configuration of an optical transceiver 100 according to an embodiment of the present invention. The configuration of the optical transceiver 100 according to the embodiment of the present invention is the same as that of the QSFP + standard optical transceiver described in Non-Patent Document 1, and FIG. 13 schematically shows the configuration. The optical transceiver 100 is installed in a data center or the like having a large number of server devices, and outputs a data transmission device that outputs data from the server device toward the optical communication network N, and an optical signal transmitted from the optical communication network N. Is provided with the function of a data receiving device that receives and outputs to the server device.

  The optical transceiver 100 shown here includes two optical multiplexers / demultiplexers 101 according to the embodiments of the present invention that combine and demultiplex the four types of monochromatic light described above, one of which is an optical multiplexer that operates as an optical multiplexer. A demultiplexer (hereinafter also referred to as an optical demultiplexer 101a), and the other is an optical demultiplexer (hereinafter also referred to as an optical demultiplexer 101b) that operates as an optical demultiplexer. In addition, in the housing 102 of the optical transceiver 100, four light emitting means 121 to 124 and four light receiving means 151 to 154 are accommodated in addition to the optical multiplexer 101a and the optical demultiplexer 101b. Each of the light emitting means 121 to 124 includes a laser diode (LD), an LD drive circuit, and the like. Each of the light receiving means 151 to 154 includes a photodiode (PD), an amplifier circuit for a signal photoelectrically converted by the PD, and the like. The optical transceiver 100 is connected with four transmission data transmission paths 111 to 114 for inputting data based on electrical signals and four reception data transmission paths 161 to 164 for outputting data based on electrical signals. ing. Further, the optical transmission line 130 for transmission, which is composed of an optical fiber and outputs an optical signal multiplexed by the WDM system, to the optical communication network N, and the multiplexed optical signal from the optical communication network N An optical transmission path 140 for reception that is input to the optical demultiplexer 101b in the optical transceiver 100 is also connected.

Next, the transmission operation and the reception operation in the optical transceiver 100 will be described with the optical communication network side as the upstream side, the signal transmission direction as the upward direction, and the reception direction as the downward direction. As a transmission operation, first, an electrical signal corresponding to each of the four systems of transmission data from a server device or the like installed on the downstream side is transmitted through the four systems of transmission data transmission paths 111 to 114. Input to means 121-124. Each of the light emitting means 121 to 124 converts the inputted electric signal into an optical signal and emits it. Further, the four light emitting means 121 to 124 emit monochromatic light having different wavelengths λ _{1 to} λ ₄ . In this example, the demultiplexing collimators C1 to C4 and the multiplexing collimator C5 are optical fiber collimators, and light emitted from each of the light emitting units 121 to 124 is transmitted through four optical multiplexers 101a via the optical fibers. Input to demultiplexing collimators C1 to C4. It optical signal consisting of monochromatic light of four different wavelengths lambda ₁ to [lambda] ₄ by is input to the optical multiplexer 101a. The optical multiplexer 101a combines the input four types of wavelengths λ _{1 to} λ ₄ and outputs an optical signal composed of the multiplexed light from the combined collimator C5. Then, an optical signal composed of multiplexed light including light of four types of wavelengths λ _{1 to} λ ₄ is transmitted to the optical communication network N via the optical transmission path 130.

On the other hand, the receiving operation, multiplexed optical demultiplexer 101b via the optical signal is an optical transmission line 140 comprising a multiplexed light including light of four different wavelengths lambda ₁ to [lambda] ₄ from the optical communication network N collimator C5 Is input. The optical demultiplexer 101b demultiplexes the input multiplexed light into four types of monochromatic light having wavelengths λ _{1 to} λ ₄ . Thereby, optical signals composed of monochromatic lights having different wavelengths λ _{1 to} λ ₄ are emitted from the demultiplexing collimators C _{1 to} C ₄ . The optical signals emitted from the demultiplexing collimators C1 to C4 are individually input to the four light receiving units 151 to 154. Each light receiving means 151-154 converts the received optical signal into an electrical signal and outputs it. The electric signals output from the light receiving units 151 to 154 are input to a downstream server device or the like via four systems of data transmission paths 161 to 164 for reception and are used for data processing.

  The above examples do not limit the scope of the invention. The configurations of the above embodiments can be implemented in appropriate combinations, and various omissions, replacements, and changes can be made without departing from the scope of the invention. The embodiments and the modifications thereof are included in the scope of the invention and the gist thereof, and are also included in the invention described in the claims and the equivalent scope thereof.

1, 1a-1k 101, 101a, 101b optical multiplexer / demultiplexer, 10 substrate,
11 Upper surface of substrate, 12 Lower surface of substrate, 13 Notch, 20a-20e Optical path deflecting unit,
30, 40 Auxiliary board, 50 Fixed plate, 100 Optical transceiver, 102 Optical transceiver housing, 111-114, 161-164 Data transmission path,
121-124 light emitting means, 130,140 light transmission path, 151-154 light receiving means,
C1-C4 optical fiber collimator (demultiplexing collimator),
C5 optical fiber collimator (combining collimator), F1-F4 interference filter,
L1-L4 single wavelength light (monochromatic light), L5 combined light (multiplexed light),
M1-M3 mirror, N optical communication network

Claims (12)

An optical multiplexer / demultiplexer that multiplexes or demultiplexes n types of light having different wavelengths, where n is a natural number,
First to nth demultiplexed light input / output units for inputting / outputting light of different single wavelengths, with the light entrance / exit as the light input / output unit,
One combined light input / output unit for inputting / outputting light obtained by combining the n types of light having different wavelengths;
Second to nth interference film filters corresponding to each of the second to nth demultiplexed light input / output units;
First to n-1 th mirrors corresponding to each of the first to n-1 demultiplexed light input / output units;
Have
The traveling direction of the light output from the first to nth demultiplexed light input / output units is defined as the front-rear direction.
The second to n-th interference film filters are disposed in front of the corresponding demultiplexed light input / output units, and selectively receive light of a single wavelength input / output to / from the corresponding demultiplexed light input / output units. Transmit and reflect light of other wavelengths,
The first to n-th demultiplexed light input / output units are two-dimensionally arranged on the same plane with the front-rear direction as a normal line when viewed from the rear,
A first mirror is disposed on the optical path of the input / output light of the first demultiplexed light input / output unit;
The kth interference film filter and the kth mirror are arranged in this order from the rear to the front on the optical path of the input / output light of the kth demultiplexed light input / output unit, where k is a natural number of 2 to n-1. And
The first mirror is disposed so as to reflect the light output forward from the first demultiplexed light input / output unit toward the second interference film filter,
The kth mirror is arranged so as to reflect the light output forward from the kth demultiplexed light input / output unit and transmitted through the kth interference film filter in the direction of the (k + 1) th interference film filter,
The kth interference film filter is arranged to reflect the light incident from the k-1th mirror toward the front,
The combined light input / output unit is disposed on the optical path of light output forward from the nth demultiplexed light input / output unit and transmitted through the nth interference film filter,
The light output from the first demultiplexed light input / output unit is input to the multiplexed light input / output unit by alternately following the first to n-1 th mirrors and the second to n th interference film filters in ascending order,
m is a natural number of 2 to n,
The m-th interference film filter transmits light having a single wavelength from light traveling from the front to the rear and inputs the light to the m-th demultiplexed light input / output unit, and transmits light having a wavelength other than the single wavelength to the m-th wavelength. Arranged to reflect toward one mirror,
The light output from the multiplexed light input / output unit alternately follows the 2nd to nth interference film filters and the 1st to n-1 mirrors in descending order, and the mth demultiplexed light in the mth interference film filter. The light input to the input / output unit and the light reflected by the first mirror are input to the first demultiplexed light input / output unit.
An optical multiplexer / demultiplexer characterized by that.   In Claim 1, the 1st interference membrane filter which selectively permeate | transmits the light of the single wavelength which the 1st light input / output part inputs and outputs is arrange | positioned ahead of the said 1st demultiplexed light input / output part, An optical multiplexer / demultiplexer, wherein a first mirror is disposed in front of the first interference film filter.   3. The first to nth light input / output units according to claim 1, wherein the first to nth light input / output units are arranged at positions that form apexes of an n-gon on the same plane, and circulate in one direction around the n-gon in ascending order. An optical multiplexer / demultiplexer, which is arranged in order in the direction to be performed. In claim 1 or 2,
The surface on which the first to nth demultiplexed light input / output units are arranged is defined as an xy plane.
The first to n-th demultiplexed light input / output units are arranged so as to form a plurality of rows parallel to the y-axis direction with the x-axis direction light as the row direction, and are arranged in the first row. From the light input / output unit of 1 as a starting point, it is arranged in order in the ascending order of conflict,
In the last row where the nth demultiplexed light input / output unit is arranged, there are arranged demultiplexed light input / output units equal to or less than the number of demultiplexed light input / output units arranged in rows other than the last row, and In each row other than the last row, the same number of demultiplexed light input / output units are arranged.
An optical multiplexer / demultiplexer characterized by that. In claim 4,
The demultiplexed light input / output unit is an even number of n ≧ 4, and is disposed in the first row and the second row,
The first to n / 2nd demultiplexed light input / output units are arranged in the first row,
The n / 2 + 1 to nth demultiplexed light input / output units are arranged in the second row,
The interference film filter and the mirror are fixed to the upper and lower surfaces of a substrate disposed between rows,
An optical multiplexer / demultiplexer characterized by that. In claim 5,
The m-1st mirror and the mth interference film filter disposed on the same plane parallel to the zx plane with the front-rear direction as the z-axis direction are fixed on the same auxiliary substrate stacked on the substrate. ,
The auxiliary substrate is configured to be rotatable around the y-axis and is fixed at a predetermined rotational position.
An optical multiplexer / demultiplexer characterized by that.   The substrate according to any one of claims 4 to 6, wherein the substrate includes a fixed plate having a plane parallel to the yz plane, and the m-1st mirror and the mth interference film filter disposed across the rows are yz. An optical multiplexer / demultiplexer having a side surface parallel to the surface, the side surface being fixed to the fixed plate. In any one of Claims 1-7,
The demultiplexed light input / output unit is disposed at a light emission position that transmits the corresponding interference film filter from the front to the rear,
The combined light input / output unit is disposed on an optical path of light that passes through the nth interference film filter from the rear to the front,
An optical multiplexer / demultiplexer characterized by that.   9. The optical multiplexer / demultiplexer according to claim 1, wherein the mirror and / or the interference film filter has a back surface facing the light incident surface as a reflection surface. 10. In any one of Claims 1-9,
Looking at the front from behind, the combined light input / output unit is disposed inward of the region where the first to nth light input / output units are disposed,
An optical path deflecting unit that forms a bent optical path between the nth interference film filter and the multiplexed light input / output unit;
An optical multiplexer / demultiplexer characterized by that.   11. The multiplexed light input / output unit according to claim 10, wherein the combined light input / output unit has a light input / output port at a front end, and the optical path deflecting unit turns back the light output from the nth light input / output unit. Optical multiplexer / demultiplexer.   Two optical multiplexers / demultiplexers are housed in a housing, one optical multiplexer / demultiplexer being an optical multiplexer and the other optical multiplexer / demultiplexer being an optical demultiplexer, wherein the two optical multiplexers / demultiplexers are An optical transceiver, wherein at least one of the optical multiplexers is the optical multiplexer / demultiplexer according to any one of claims 1 to 10.

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