JP6317216B2 - Optical input / output device - Google Patents

Description

  The present invention relates to an optical input / output device used for an optical network.

  In recent years, video distribution using an optical communication network has started actively. In video distribution, the same information is transmitted to multiple users, so it is more efficient to use the network when one signal light is branched to the other path during transmission than when it is transmitted individually. Can do.

  A typical device that performs multi-branching is a splitter. In this device, a signal sent from one path can be branched at a predetermined intensity ratio on the other path. However, when the splitter is used, if the user of the transmission destination stops using the service, if the signal is continuously transmitted as it is, an excessive loss is generated and the uselessness is wasted. To avoid this, it is necessary to replace the splitter with a different number of branches and branch ratio.

  An optical switch is a device that can change the path of signal light. Among optical switches, a spatial optical system optical switch that switches a light path in free space is superior to other systems from the viewpoint of high-density mounting and power consumption reduction, and technological development is progressing in recent years.

  The basic configuration of the spatial optical system optical switch will be described. In general, a spatial optical system optical switch is composed of several lenses and a light beam deflecting element that changes the traveling direction of a light beam in a free space between an input fiber and an output fiber. Typical optical switches include an input / output fiber array and a collimating lens array, an optical cross-connect switch (OXC) composed of two sets of light beam deflection elements, an input / output fiber array and a collimating lens array, a lens group, and a dispersion element. And a wavelength selective switch (WSS) including a beam deflection element group.

  In an optical switch such as that described above, it is usually not possible to dynamically switch the switching branched into multiple paths or the branching ratio between the multiple paths. In order to cope with a change in the service of the user and an optimum change in the branching ratio due to the replacement, an optical switch that can branch into many directions and can dynamically change the branching ratio is important.

JP 2014-35377 A

Y. Sakamaki et al, ECOC 2011 Technical Digest, Th.12.A.3. (2011)

  In multicast distribution, the required signal light intensity differs depending on the transmission distance. In order to effectively use the intensity of signal light, it is important to allocate as much light as necessary to each transmission destination. Further, when the receiver is changed or the state of the transmission network is changed, it is required that the branching ratio can be changed accordingly. However, with a conventional splitter, it is difficult to make the branching ratio variable.

  The present invention has been made in view of the above-described conventional problems, and the problem of the present invention is that when the change of the receiver or the state of the transmission network is changed by changing the branching ratio of the signal light, An object of the present invention is to provide an optical input / output device capable of setting a branching ratio accordingly.

  In order to solve the above-described problem, the invention described in one embodiment is arranged in a matrix form with a first port of one channel and a second port of a plurality of channels for inputting and outputting signal light. A plurality of pixels, and the phase shift amount based on the phase value set according to the pixel position is given to each pixel with respect to the signal light input from the first port, and spatial phase modulation is performed. And a phase to be set for each pixel of the phase modulation element so that the signal light is optically coupled to two or more desired channels among the plurality of channels of the second port. A pattern generation unit that generates a pattern; and a drive unit that converts the generated phase pattern into a drive signal for each pixel of the phase modulation element and drives the pixel of the phase modulation element according to the drive signal, The pattern generator determines two or more periodic phase patterns based on the positions of two or more channels that optically couple the signal light of the second port, and the determined two or more periodic phases An optical input / output device that generates the phase pattern set in each pixel of the phase modulation element by superimposing a pattern.

It is a figure which shows schematic structure which looked at the input / output device of 1st Embodiment from the x-axis direction. It is a figure which shows the structural example of a phase modulation element. It is a figure which shows the example of the phase pattern for making light couple | bond with the output port used as a reference | standard, and the example of the diffraction from the reflection type phase modulation element in the phase pattern. (A) is a figure which shows the example of the deflection characteristic by a single periodic phase pattern, (b) is a figure which shows the example of the deflection characteristic at the time of superimposing two periodic phase patterns. (A) is an example of a phase modulation element in which different phase patterns are set for each of a plurality of regions, and (b) and (c) are diagrams showing examples of periodic phase patterns and phase changes in the respective regions. It is a figure which shows schematic structure seen from the x-axis direction about the input / output device of 2nd Embodiment. It is a figure which shows the structural example of the phase modulation element in the case of the optical structure with wavelength selection system. It is a figure which shows schematic structure seen from the x-axis direction about the input / output device of 3rd Embodiment. It is a figure which shows schematic structure seen from the x-axis direction about the input / output device of 4th Embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
[Configuration of optical input / output device]
First, the optical input / output device of this embodiment will be described. FIG. 1 is a diagram illustrating a schematic configuration of the input / output device according to the first embodiment viewed from the x-axis direction. In the example shown in FIG. 1, the direction in which the ports for inputting and outputting signal light are arranged is the y axis, and the direction in which the signal light propagates is the z axis. The input light (signal light) is emitted to the space through the optical fiber 11 and given to the optical element 13 through the collimator lens 12. The light emitted from the optical element 13 is reflected by the phase modulation element (phase modulator) 14 after being subjected to a phase change corresponding to the incident position on the phase modulation element 14, and then reflected again via the optical element 13. 12, 15-1 to 15-n and optical fibers 11, 16-1 to 16-n. The position and intensity of the signal light reflected and output to the optical element 13 according to the phase pattern set in the phase modulation element 14 are selected, and predetermined light of the plurality of optical fibers 16-1 to 16-n is selected. It is output at an arbitrary intensity from the fiber 16m.

  In the optical input / output device of this embodiment, a path (channel) constituted by the optical fiber 11, the collimating lens 12, and the optical element 13 forms a first port, and the optical element 13 and the collimating lenses 12, 15-1 are formed. -15-n and a path (channel) constituted by the optical fibers 11 and 16-1 to 16-n form a second port. That is, the first port is composed of one channel, while the second port is composed of a plurality of channels.

  As the optical element 13, means for changing the emission direction of the signal light so that the input light is emitted toward the phase modulation element 14 can be used. For example, a lens, a prism, a diffraction grating, or the like is used. Can do. As the optical element 13, means for converting the light input to the optical element 13 via the optical fiber 11 and the collimating lens 12 so that the angle when entering the phase modulation element 14 changes depending on the position on the y-axis. For example, a lens, a prism, a concave mirror, a diffraction grating, or the like can be used.

[Configuration of phase modulator]
Next, the phase modulation element 14 used in this optical input / output device will be described in detail. FIG. 2 is a diagram illustrating a configuration (light irradiation region) when the reflective phase modulation element is viewed from the z-axis direction. The phase modulation element 14 includes a large number of pixels 41-11 to 41-pq in which the phase of light can be independently controlled in each of p × q pixels arranged in a matrix on the xy plane, and the phase of each pixel. A driver element 42 for controlling the light source and a reflecting portion 43 on the back surface. In the above optical input / output device, the light irradiation region when light is incident on the phase modulation element is the region R shown in FIG. The wavefront of the emitted light (signal light) is controlled by giving a specific phase pattern to each of the pixels 41-11 to 41-pq in the region R, and the traveling direction of the emitted light and the optical power in that direction are controlled. I can do it.

  The phase modulation element 14 can be realized by using, for example, LCOS (Liquid Crystal On Silicon). In this device, the orientation direction of the liquid crystal material can be controlled by the voltage applied to the driver electrode, and the phase of the emitted light can be controlled by changing the refractive index of the liquid crystal felt by the input signal. is there. A reflective phase modulator can be realized by using the front electrode as a transparent electrode and the back electrode as a reflective electrode. Instead of the liquid crystal material, a material exhibiting an electro-optic effect may be used. The phase modulation element 14 can also be realized by using a MEMS (Micro Electro Mechanical System) mirror. For example, by applying a voltage, it is possible to change the optical path length for each pixel and to control the phase by displacing the mirror corresponding to the position of each pixel in the z-axis direction.

  In the input / output device of the present embodiment, although not shown, phase pattern generation means connected to the driver element 42 is provided. The phase pattern generating means generates a phase pattern in which the signal light is optically coupled to a desired channel of the second port, and the driver element 42 converts the generated phase pattern into a drive signal, and converts it into the converted drive signal. Based on this, by driving each pixel of the phase modulation element 14, it is possible to optically couple to a desired channel of the second port. A method for generating a phase pattern in the phase pattern generating means will be described below.

[Phase pattern generation method]
A method of generating a phase pattern in which a desired channel is selected from a plurality of channels of the second output port and optical coupling of signal light is performed by the phase modulation element will be described. First, a method for selecting one reference channel (reference channel) will be described. FIG. 3 is a diagram illustrating an example of a phase pattern for coupling light to one reference channel and an example of diffraction from a reflective phase modulation element. The channel is selected by controlling the diffraction angle of light incident on the phase modulation element, for example. By setting the phase to be set to the saw shape 51 as shown in FIG. 3, the diffraction angle of the outgoing wave from the phase modulation element can be controlled as shown in FIG. Here, the diffraction angle θ ₀ , that is, the angle θ ₀ formed by the emitted light with respect to the normal direction of the phase modulation element is:
sin θin plus sin θo = m · λ / Λ Equation (1)
Given in. In equation (1), θin is the angle formed by the incident light with respect to the normal direction of the phase modulation element, m is the diffraction order, λ is the wavelength of the incident light, and Λ is the length of one period of the phase pattern.

Here, consider the wavefront of light when subjected to phase modulation. For simplicity, consider θin = 0.
When receiving the phase modulation as described above, a linear phase shift as shown in the equation (2) is spatially given to the light incident on the phase modulation element.

This tilts the wavefront and deflects the light.

Based on the position of the reference channel, the angle θ ₀ to be emitted is determined to determine the periodic phase pattern of the period Λ that satisfies the above formula (1), and the phase pattern of the determined period Λ is given to the phase modulation element. By setting, it is possible to optically couple to the reference channel of the second port. Θo may be adjusted by changing Λ so that optical coupling is obtained in the reference channel.

  Further, a configuration may be adopted in which the reference channel of the second port is arranged at the position of θo that satisfies the above formula (1), and output to the reference channel. The actual channel arrangement may be set according to the equation (1), and there may be a slight deviation from the position determined by the equation (1). When there is a deviation, the amount of attenuation increases as the deviation from the position increases.

  Next, a method for optically coupling signal lights by selecting a channel other than the reference channel of the second port will be described. A phase pattern obtained by superimposing a periodic phase pattern having a different period w on a periodic phase pattern having a reference period Λ determined based on the position of the reference channel of the second port using the above equation (1). By setting, signal light is optically coupled to a plurality of channels. A case where both the periodic phase pattern of the reference period Λ and the periodic phase pattern of different periods w are sawtooth waves will be described as an example.

The phase pattern that provides optical coupling to the reference channel of the second port is, for example, a sawtooth-shaped periodic phase pattern 61 as shown in the upper part of FIG. 4A, and the sawtooth wave has a period of Λ. , The amplitude is 2π. When only this phase pattern exists, light is emitted only in the output port direction θo as shown in the lower part of FIG. With respect to this periodic phase pattern, as shown in the upper part of FIG. 4B, the phase φ in one cycle of the superposed sawtooth wave is φ = k × y% w Equation (3)
(% Represents the remainder operator)
When the periodic phase pattern 62 is superposed, a peak 64 appears in the angle direction θs as shown in the lower part of FIG. 4B, and the optical power of the peak 63 can be distributed. Here, when w is the length of one period of the periodic phase pattern to be superimposed and k is a constant, the emission angle θs to the position where optical coupling is obtained can be expressed by the following equation (4).
θs = θo + arcsin (m · λ / w) Equation (4)
m is the order of diffraction and is an integer. Here, it is defined as Δθs = θs−θo. In Expression (4), by selecting w so that θs is in the angular direction in which the channel of the second port is arranged, signal light is transmitted to each of the channels arranged in the θs direction and θo direction with respect to one input. Optical coupling is possible. In other words, from the equation (4), if θo is taken as a reference, it is possible to optically couple to a predetermined channel by arranging the output port at the position of Δθs = arcsin (m · λ / w). The actual channel arrangement may be set according to the equation (4), and there may be a slight deviation from the position determined by the equation (4). When there is a deviation, the amount of attenuation increases as the deviation from the position increases.

  The above equation (4) can also be derived by frequency expansion of an equation showing a phase shift by the phase modulation element. Here, consider the wavefront of light when subjected to phase modulation. When the phase modulation as described above is performed, a phase shift as shown in Expression (5) is spatially given to the light incident on the phase modulation element.

  Here, Jm is a coefficient indicating the intensity ratio. From equation (5), light is diffracted to an angle θs represented by equation (4) in addition to the angle of inclination θo.

  Note that the lower limit value of w can be determined by the maximum value θmax and the minimum value θmin determined by the size of the channel of the second port in the y-axis direction (port parallel direction). The range of w is designed so that the angle Δθs formed by the angle θs at which the channel of the second port is disposed and the angle θo is within the range of the maximum value θmax and the minimum value θmin. When θo is in the range of θmin to θmax, the condition for θs to enter θmin to θmax is | arcsin (m · λ / w) | <θmax−θmin. Since m is an integer, | arcsin (m · λ / w) | ≧ | arcsin (λ / w) | is always satisfied, and the periodic phase pattern superimposed for optical coupling to the plurality of channels of the second port The period w falls within the range of w> λ / sin (θmax−θmin).

Further, the expression (3) further uses an arbitrary constant b to change the phase φ to φ = k × (y% w) + b (6)
Can be rewritten in a form including the initial phase. Therefore, the periodic phase pattern having the additional period w ₁ determined by the equation (6) is superimposed on the periodic phase pattern having the reference cycle Λ determined by the equation (3), and a further different cycle w ₂ is set. The phase φ _{2 in} one cycle is
φ ₂ = k ₂ × (y% w ₂ ) + b ₂ formula (7)
By setting the phase pattern generated by superimposing the periodic phase pattern represented by: θ _s2 = θ _o + arcsin (m × λ / w ₂ ) Equation (8)
Further, it is possible to further optically couple the channels arranged in the angle direction, and simultaneous output to three ports is possible. Similarly, simultaneous output to four or more ports is possible by superimposing four or more periodic phase patterns having different periods. That is, as described above, the period of the periodic phase pattern is determined based on the position of the channel where the signal light is to be optically coupled, and a plurality of periodic phase patterns having different periods are superimposed and set in the phase modulation element. A phase pattern may be generated.

  Note that the periodic phase pattern is not limited to a sawtooth wave, and may be a sine wave, a rectangular wave, or a combination of these. Further, the waveform may be different for each periodic phase pattern to be superimposed.

[Adjusting the output light intensity ratio]
Next, a method for adjusting the output intensity ratio when coupled to a plurality of channels of the second port will be described.

K, and the period by controlling the amplitude of the periodic phase pattern, which overlaps with the optical power of the emission direction by serving as a reference periodic phase pattern k ₂ is changed to overlap with the formula (7) in equation (4) It is possible to control the ratio of the optical power in the emission direction by the characteristic phase pattern. That is, it is possible to set the branching ratio for each channel of the second port. In the case where three or more periodic phase patterns are superimposed, the branch ratio for each channel of the second port can be set similarly.

Further, by dividing the phase modulation element 14 into a plurality of regions and setting periodic phase patterns with different periods in each region, it is possible to output to a plurality of channels of the second port. In FIG. 5, by setting a periodic phase pattern having a period of Λ1 in region A and a periodic phase pattern having a period of Λ2 in region B, θ _o1 determined by (Expression 9) and (Expression 10) At the same time, light is diffracted to θ _o2 .
sin θin plus sin θo1 = m · λ / Λ1 Formula (9)
sin θin plus sin θo1 = m · λ / Λ2 Equation (10)

The intensity of light diffracted by θ _o1 and θ _o2 can be adjusted by changing the width and position of each of the regions A and B in FIG. If the width is the same, the diffracted light corresponding to the region becomes stronger as the light intensity is higher, and if the light intensity is the same, the diffracted light corresponding to the region becomes stronger as the range is larger.

  According to the optical input / output device of this embodiment, by superimposing a plurality of periodic phase patterns, it is possible to output optical power to a plurality of channels by distributing optical power in a direction corresponding to the period. In addition, the light intensity can be controlled with high accuracy by controlling the amplitude of the periodic phase pattern to be superimposed.

  By setting the phase modulation element 14 as described above, when signal light is input from the first port, it can be optically coupled to a predetermined channel among the plurality of channels of the second port and output. However, the input and output directions of signal light may be interchanged. That is, when signal light is input from a predetermined channel among a plurality of channels of the second port, it is optically coupled to the first port and output. When signal light is input from the second port, signal light from different output channels may be input with a time shift so as not to interfere with each other. The ratio of the coupling ratio to the first port for each input channel when the signal light signal light is input from the second port and optically coupled to the first port is the same as the branching ratio when the light is divided. is there.

(Second Embodiment)
FIG. 6 is a diagram illustrating a schematic configuration of the input / output device according to the second embodiment viewed from the x-axis direction. This embodiment is different from the first embodiment in that a wavelength dispersion element 17 is disposed between the collimating lens 12 and the phase modulation element 14. Only parts different from the input / output device of the first embodiment will be described. The wavelength dispersion element 17 may be disposed at any position between the collimating lenses 12, 15-1 to 15-n and the optical element 13, or between the optical element 13 and the phase modulation element 14.

  In this embodiment, for example, WDM (Wavelength Division Multiplexing) light that bundles wavelengths λp to λq can be used as the input signal light. In the example shown in FIG. 6, the wavelength dispersion element 17 is arranged between the collimating lenses 12, 15-1 to 15-n and the optical element 13 so that the condensing position is different for each wavelength, and the output port is different for each wavelength. And light intensity can be selected. The wavelength dispersion element 17 has diffraction performance in the direction perpendicular to the paper surface, and may irradiate light at a position different in the direction perpendicular to the paper surface of the phase modulation element 14 depending on the wavelength of the input light.

  As shown in FIG. 7, the phase modulation element 14 used in this embodiment can be configured to independently control the phase pattern for each of a plurality of regions. That is, in the phase modulation element 14 of the present embodiment, a light irradiation region decomposed into wavelength channels is formed. In addition, when incident light is converted into a WDM signal and dispersed in the x-axis direction (for example, the direction perpendicular to the paper surface of FIG. 6) by a diffraction grating, the incident area differs for each wavelength channel as shown in FIG. The parallel regions R1 to Rn are obtained. In this case, different output ports and output light intensities can be set for each wavelength channel by independently controlling the phase patterns of the regions R1 to Rn.

  In this embodiment, since the optical configuration has wavelength selectivity, signals of different wavelengths are irradiated to different regions on the phase modulation element 14. Therefore, by setting a phase pattern generated by superimposing different periodic phase patterns for each region, it is possible to select different output ports and light intensities for each wavelength.

(Third embodiment)
FIG. 8 is a diagram illustrating a schematic configuration of the input / output device of the third embodiment viewed from the x-axis direction. In the first embodiment, a reflection type phase modulation element is used, but in this embodiment, an optical input / output device is configured using a transmission type phase modulation element. FIG. 8 shows a configuration example of an optical input / output device using a transmissive phase modulation element as viewed from the x-axis direction. Only the parts of the input / output device of the third embodiment different from those of the input / output device of the first embodiment will be described.

  In the optical input / output device of this embodiment, as shown in FIG. 8, the optical fiber 21, the collimating lens 22, the optical element 23, the phase modulation element 24, the optical element 25, and the collimating lens 26 are arranged from the input side. -1 to 26-n and optical fibers 27-1 to 27-n are arranged.

The phase modulation element 24 is configured by a reflection type phase modulation element. That is, unlike the phase modulation element 14 of the first embodiment, since the reflection part 43 is not provided on the back surface of the driver element 42, the light incident from the optical fiber 21 side is subjected to a phase change. The light passes through the optical fibers 27-1 to 27-n. As with the phase modulation element 14 of the first embodiment, the phase modulation element 24 is provided with electrodes on the front and back surfaces. In the phase modulation element 24, both the front and back electrodes are transparent electrodes. Thus, a transmissive phase modulator can be realized. In the reflection-type phase modulation element 14, as described above, the light incident on the phase modulation element 14 is emitted at a predetermined angle (θ ₀ , θs) with respect to the normal direction on the incident surface. The phase modulation element 24 that is a type differs in that light incident on the phase modulation element 24 is emitted at a predetermined angle (θ ₀ , θs) with respect to the normal direction on the surface opposite to the incident surface. Other than that, it functions similarly to the reflection type phase modulation element 14.

  In the configuration of FIG. 8, after the channel and the output light intensity of the input light from one optical fiber 21 shown in the left hand are adjusted, the plurality of optical fibers 27-1. Output to a predetermined one of n. The input light is emitted to the space via the optical fiber 21 and is incident on the first optical element 23 via the collimator lens 22. The light emitted from the first optical element 23 is transmitted by the phase modulation element 24 to the second optical element 25 after a phase change corresponding to the incident position is given. The light transmitted through the phase modulation element 24 is connected to the optical fibers 27-1 to 27-n via the collimating lens arrays 26-1 to 26-n. The signal light is selected from the output port connected to the second optical element 25 and the light intensity according to the phase pattern given to each element of the phase modulation element 24, whereby a plurality of optical fiber optical fibers 27-1 to 27-27. -N is output at an arbitrary intensity from a predetermined optical fiber 27m.

  By setting the phase modulation element 24 as described above, when signal light is input from the first port, it can be optically coupled to a predetermined channel among the plurality of channels of the second port and output. However, the input and output directions of signal light may be interchanged. That is, when signal light is input from a predetermined channel among a plurality of channels of the second port, it is optically coupled to the first port and output. When signal light is input from the output port, signal light from different output channels may be input with a time shift so as not to interfere with each other. The ratio of the coupling ratio to the first port for each input channel when the signal light is input from the second port and optically coupled to the first port is the same as the branching ratio when the light is divided.

(Fourth embodiment)
FIG. 9 is a diagram illustrating a schematic configuration of the input / output device of the fourth embodiment viewed from the x-axis direction. This embodiment is different from the third embodiment in that the wavelength dispersion elements 28 and 29 are disposed between the collimating lens 22 and the phase modulation element 24 and between the phase modulation element 24 and the collimation lenses 26-1 to 26-n. Is different. Only the parts of the input / output device of the fourth embodiment different from those of the input / output device of the third embodiment will be described.

  In this embodiment as well, as in the second embodiment, WDM (Wavelength Division Multiplexing) light that bundles wavelengths λp to λq can be used as the input signal light. As shown in FIG. 9, a wavelength dispersion element 28 is disposed between the collimating lens 22 and the optical element 23, and a wavelength dispersion element 29 is disposed between the collimating lenses 26-1 to 26-n and the optical element 25. It is possible to select a different output port and light intensity for each wavelength by making the condensing position different for each wavelength. In FIG. 9, the wavelength dispersion element has diffraction performance in the direction perpendicular to the paper surface, and irradiates light at different positions in the direction perpendicular to the paper surface of the phase modulation element 14 depending on the wavelength of the input light. The wavelength dispersion elements 28 and 29 may be disposed between the optical element 23 and the phase modulation element 24 and between the phase modulation element 24 and the optical element 25.

DESCRIPTION OF SYMBOLS 11, 16-1 to 16-n Optical fiber 12, 15-1 to 15-n Collimating lens 13 Optical element 14 Phase modulation element 17 Wavelength dispersion element 21, 27-1 to 27-n Optical fiber 22, 26-1 26-n collimating lens 23, 25 optical element 24 phase modulation element 28, 29 wavelength dispersion element 41-11 to 41-pq pixel 42 driver element 43 reflecting portion

Claims (6)

A first port of one channel and a second port of a plurality of channels for inputting and outputting signal light;
A plurality of pixels which are plane arranged in a matrix, wherein the first signal light input from the port, the plurality of pixels the phase change amount based on the set phase values depending on the pixel position A phase modulation element that deflects light by spatial phase modulation given by
A pattern generator that generates a phase pattern to be set in each pixel of the phase modulation element so that the signal light is optically coupled to two or more desired channels of the plurality of channels of the second port;
A drive unit that converts the generated phase pattern into a drive signal for each pixel of the phase modulation element and drives the pixel of the phase modulation element according to the drive signal;
The pattern generation unit determines two or more periodic phase patterns based on positions of two or more channels that optically couple the signal light of the second port, and the two or more determined periodicities The phase pattern to be set for each pixel of the phase modulation element is generated by superimposing the phase pattern, and the width and position of a plurality of regions of the phase modulation element for setting the periodic phase pattern having different periods are changed. Thus , the optical input / output device is characterized in that a branching ratio which is an intensity ratio of the signal light optically coupled to the two or more channels is adjusted . The optical input / output device according to claim 1,
The pattern generation unit emits the signal in the normal direction of the phase modulation element based on the position of a reference channel serving as one of two or more channels that optically couple the signal light of the second port. Λ satisfying sin θin plus sin θo = m · λ / Λ where θ _{0 is the} angle to be made by the signal light, θin is the angle made by the incident signal light, m is the diffraction order, and λ is the wavelength of the incident light. , Determine a reference period Λ of the periodic phase pattern,
Based on the position of one or more additional channels other than the reference channel among the two or more channels that optically couple the signal light of the second port, the reference channel and the additional channel form. the angle θn (n = 2~N), the wavelength of the input light lambda, when the diffraction order of m, add w _n satisfying θn = arcsin (m · λ / w n) of the periodic phase pattern Determine the period w _n to be
Light output device and generates said phase pattern to be set to each pixel of the phase modulating element by superimposing two or more periodic phase pattern having different periods lambda, w _n the determined . The optical input / output device according to claim 1,
An optical input / output device in which a periodic phase pattern having a different period is superimposed for each region in a plane of the phase modulation element. The optical input / output device according to claim 1,
The optical input / output device, wherein the plurality of periodic phase patterns are waveforms of a sawtooth wave, a sine wave, a rectangular wave, or a combination thereof. The optical input / output device according to claim 1,
An optical input / output device, wherein a ratio of amplitudes of the plurality of periodic phase patterns is determined by an optical coupling ratio of a channel to be optically coupled. The optical input / output device according to any one of claims 1 to 5,
The phase pattern generated by the pattern generation unit is generated by superimposing three or more periodic phase patterns having different periods.

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