JP6238413B2 - Optical signal processor - Google Patents

Description

  The present invention relates to an optical signal processing device, and more particularly to an optical signal processing device that is simple to mount and capable of multi-port operation while being low in cost.

  With the construction of a large-capacity optical communication network that has shown rapid progress in recent years, wavelength division multiplexing (WDM) communication technology has attracted attention and the spread of facilities has progressed. However, in WDM nodes, optical signals are directly transmitted. In general, a path is switched after being converted into an electric signal once without being controlled. However, in the above method, there is a concern that the processing load at the node is increased, the communication speed is limited, and the power consumption is increased. For this reason, transparent network systems such as ROADM (Reconfigurable Optical Add / Drop Multiplexer) are increasing in importance in order to perform signal processing without using optical switching, and thus constitute ROADM. Development of optical devices such as a wavelength selective switch (WSS) and a tunable dispersion compensator (TODC: Tunable Optical Dispersion Compensator) has been energetically advanced (for example, see Non-Patent Document 1).

  A general configuration and operation principle of an optical signal processing device such as WSS or TODC will be described. The WDM signal input from the input optical fiber propagates through the space as collimated light by the collimator, passes through a plurality of lenses and a diffraction grating for wavelength demultiplexing, and is then condensed again through the lenses. A spatial light modulator (SLM, Spatial Light Modulator) for giving a desired phase change of the optical signal is disposed at the condensing position. Typical examples of the SLM include a micromirror array using MEMS (Micro-electro mechanical system) technology, a liquid crystal cell array, DMD (Digital Mirror Device), LCOS (Liquid crystal on silicon), and the like. As a result, each optical signal is given a desired phase change and reflected. Each of the reflected optical signals enters the diffraction grating through the lens, is wavelength-multiplexed, and then couples to the output fiber through the lens. If the optical signal processing device is used as a compensation device based on the configuration of one input fiber and one output fiber, as represented by TODC, the input fiber and output fiber can be used together and a circulator can be used. A technique of separating signals before and after compensation is frequently used. In addition, when configuring a switching device such as WSS, a signal reflected by arranging a plurality of output fibers in addition to at least one input fiber and deflecting the signal light to a desired angle by the SLM. The output fiber to which the light is coupled can be selected and switched.

  In a WDM node, a configuration in which a plurality of optical signal processing devices as described above are mounted simultaneously is common. FIG. 1 is a configuration diagram in the case where a WSS is configured by the above-described optical signal processing device, and a plurality of WSSs are mounted on one WDM node (optical node). The optical signal incident on the optical node is set to a wavelength selective drop or through path by the WSS group 101 of the wavelength cross-connect function unit 107. The optical signal dropped in the WSS group 101 is routed according to the wavelength by the wavelength demultiplexing function unit group 102, enters the receiver group 103, and reaches a desired receiver. On the other hand, the optical signal transmitted from the transmitter group 104 in this optical node passes through the wavelength multiplexing function unit group 105 and is transmitted to the adjacent node by the WSS group 106 of the wavelength cross-connect function unit 107. The

  In such a form, the wavelength and the route are determined by the position of the port that is input to or output from the optical node (Colored / Directed). For this reason, in order to give a more flexible function depending on the method, a method for transmitting / receiving a signal of an arbitrary wavelength by replacing the wavelength demultiplexing function unit group 102 and the wavelength multiplexing function unit group 105 with a WSS group ( Colorless), and by inserting a matrix switch group between each of the wavelength demultiplexing function unit group 102 and the receiver group 103, and between the transmitter group 104 and the wavelength multiplexing function unit group 105, a signal from an arbitrary path can be obtained. Various forms such as a method for enabling transmission and reception (Directionless) have been proposed. Here, in any form, the wavelength cross-connect function unit 107 shown in FIG. 1 often requires as many WSS sets as the number of routes, with one set for add and one for drop. For this reason, a low-cost 2-in-1 WSS in which two WSS functions are combined into one device is very attractive due to many advantages such as a reduction in initial introduction cost, a reduction in power consumption, and a reduction in load on the control system. Of course, the functions integrated into one device are not limited to the functions for two devices, and even different functional forms such as WSS and TODC are highly effective. Furthermore, in the case of a device that realizes multiple inputs and multiple outputs such as WSS, it is directly connected to the scale of an optical node system that can realize an increase in the number of input / output ports. Exists.

Dan M. Marom, et al. , “Wavelength-Selective 1 K Switches Using Free-Space Optics and MEMS Micromirrors: Theory, Design, and Implementation,” JE. Lightwave Technology, Vol. 23, no. 4, pp. 1620-1630, 2005

  FIG. 2 shows a conceptual diagram of a general configuration of the optical signal processing apparatus that integrates a plurality of functions, and a more detailed operation will be described. In the following, the WSS function for two units is integrated into the optical signal processing apparatus, the direction of wavelength demultiplexing by the diffraction grating is the x-axis (also referred to as wavelength dispersion axis), and the optical signal is output from the fiber. The advancing direction at this time is defined as the z axis, and the direction perpendicular to the x axis and the z axis is defined as the y axis. Further, in order to simplify the description, one input port and two output ports in one WSS are used, but the number and configuration are not limited to this description. The principal ray of the optical signal emitted from the first WSS function unit is indicated by a solid line, and the principal ray of the optical signal emitted from the second WSS function unit is indicated by a broken line.

  First, the optical signal processing apparatus having the configuration shown in FIG. Input / output to the optical signal is performed via the input / output port group 201. The input / output port group 201 includes a first input / output port group 201-1 corresponding to the first WSS function unit, and a second input / output port group 201-1. It can be divided into a second input / output port group 201-2 corresponding to the WSS function unit. In the configuration in FIG. 2A, the first input / output port group 201-1 is an array of the lower three optical fibers in FIG. 2A, and the second input / output port group 201-2 is in the upper side. Illustrated in an array of three optical fibers. The traveling directions of the optical signals emitted from the first input / output port group 201-1 and the second input / output port group 201-2 are both parallel, and in this example coincide with the z axis. An optical signal emitted from the input / output port group 201 to the space propagates while spreading at a certain numerical aperture (NA) according to the beam diameter confined in the port. In general, the input / output port group 201 is often realized by a combination of an optical fiber array and a microlens array 202 so that an optical signal emitted from each input / output port becomes collimated light. The optical signal propagated through the space is Fourier-transformed by the lens group 203 arranged separately for each WSS function unit, and is subjected to position / angle conversion. Thereafter, the light is demultiplexed in the x-axis direction by entering the diffraction grating 205 at a predetermined angle for each WSS functional unit via the lens 204, and further collected on the spatial light modulator 207 via the lens 206. To be lighted. The spatial light modulator 207 has a beam deflection function, and from this, it is possible to switch the output port by appropriately controlling the deflection angle. At this time, the optical axes related to the first input / output port group 201-1 intersect the second input / output port group 201-2 so that they intersect at a certain point on the upper side of the spatial light modulator 207 in FIG. The optical axes involved are each optically designed to intersect at a certain point on the lower side of the spatial light modulator 207. That is, for each WSS functional unit, the optical signal collected on the spatial light modulator 207 is collected independently at different positions in the Y-axis direction. By using the spatial light modulator 207 and setting the deflection angle independently for each WSS function unit, the WSS function for two units can be realized by one device.

  The optical signal processing apparatus that integrates a plurality of functions is not limited to the configuration shown in FIG. FIG. 2B shows a configuration example of the optical signal processing apparatus when the lens group 203 and the lens 204 are omitted. Also in this example, the traveling directions of the optical signals emitted from the first input / output port group 201-1 and the second input / output port group 201-2 are both parallel, and in this example, coincide with the z axis. . In order to collect light at different positions on the spatial light modulator 207 for each WSS function unit, the lens 206 that was one in the configuration of FIG. 2A is replaced with the lenses 206-1 and 206-2. Multiple functions can be aggregated by separating them from each other.

  However, in order to realize an optical signal processing apparatus that integrates a plurality of functions as described above, it is necessary to pay careful attention to optical design so that crosstalk between WSS function units does not occur. With reference to FIG. 3, the concept of crosstalk that can occur between WSS function units in the optical signal processing device of the configuration example of FIG. 2B will be described. FIG. 3A is a side view of the simplified optical signal processing device shown in FIG. 2B, and FIG. 3B shows a spatial light modulator of the optical signal processing device in FIG. It is a figure for demonstrating the beam condensed. The radii of the beams related to the two WSS function units that collect light so that the same spatial light modulator 207 is divided into regions along the y axis are w1 and w2, respectively. A deviation amount of (pitch) is assumed to be Δy. Also, assuming that the angle difference when each beam is incident on the spatial light modulator 207 is θ, the wavelength of light is λ, and the shift amount of the focal position with respect to the reflection surface of the spatial light modulator 207 is z1 and z2, respectively. The coupling efficiency η of the two beams can be obtained as shown in Equation (1).

  In general optical devices, the difference θ of the beam incident angle between each WSS function unit is designed to be 0 in order to simplify the optical arrangement and shorten the optical device in the y-axis direction. Furthermore, z1 and z2 are also designed to be 0 from the viewpoint of reducing the loss of each WSS function unit, and consideration is given so that the focal point of the beam coincides with the reflection surface of the spatial light modulator 207. In view of this point, equation (1) can be summarized as equation (2) below.

  As is clear from equation (2), the crosstalk that can occur between the WSS function units decreases the beam diameter of each WSS function unit, and increases the difference Δy in the beam focusing position related to each WSS function unit. It can be reduced by designing.

  On the other hand, as mentioned above, WSS has an important issue of increasing the number of ports. The calculation of the number of ports will be described with reference to FIG. FIG. 4A is a side view of the simplified optical signal processing device shown in FIG. 2B, and FIG. 4B is a diagram illustrating a spatial light modulator of the optical signal processing device in FIG. It is a figure for demonstrating the beam deflection angle set. Based on FIG. 4, when only a certain WSS function unit is focused, the coupling ratio between ports with respect to the beam deflection angle θ generated by the setting of the spatial light modulator 207 is obtained from Expression (1). In general WSS, as described above, z1 and z2 are designed to be 0 from the viewpoint of loss reduction, and the focus of the beam is considered to coincide with the reflection surface of the spatial light modulator 207. Since only the deflection angle φ can be controlled by the spatial light modulator 207, of course, there is no position fluctuation of the two beams to be calculated. Therefore, Δy = 0 and the beam diameter is w1 = w2. Is established. In view of this point, Expression (1) can be summarized as Expression (3) shown below.

For η shown above, the actual crosstalk can be calculated by applying Equation (4).

  When a certain deflection angle θ is set according to Equation (3), the coupling between the light incident on the spatial light modulator 207 and the beam polarized by the spatial light modulator 207, so-called crosstalk between ports, is expressed using η. It means that you can. It should be noted that the maximum polarization angle of the spatial light modulator 207 is finite. That is, in order to increase the number of ports while the wavelength λ to be used is determined and the crosstalk between ports is maintained at a certain value (in other words, it can be considered that η is maintained at a certain value) Only the beam diameter w1 of the incident light focused on the spatial light modulator 207 has a degree of freedom. Of course, w1 cannot be set without limitation, and is limited by the total height H of the spatial light modulator 207. Therefore, the number of ports cannot be increased simply by arranging two or more WSS function units in the y-axis direction.

  As described above, it is difficult to overcome the relationship between the crosstalk between ports and the number of ports only by arranging them in the y-axis direction. Therefore, as a next policy, consider arranging WSS function units in the x-axis direction. An example of this configuration is shown in FIG. The basic operation principle of the optical signal processing apparatus shown in FIG. 5 is the same as that described in the previous examples, but the spatial light modulator 505 is divided into regions in the x-axis direction for each WSS function unit. Is different. This eliminates the need to consider the crosstalk between the WSS function units shown in Equation (1), and allows a large beam in the y-axis direction to be designed. is there. However, since the first WSS function unit and the second WSS function unit need to be focused at different positions on the x-axis on the spatial light modulator 505, the same diffraction gratings are simply arranged in the x-axis direction. By simply disposing, it is necessary to separately configure the input / output port group 501, the microlens array 502, the diffraction grating 503, and the lens 504 for each WSS function unit. In this case, it is essential to prepare all optical components other than the spatial light modulator 505 separately and to perform alignment separately, and it is difficult to reduce the cost from the viewpoint of preparing the members and from the viewpoint of mounting load. Further, since it is necessary to consider a space layout for arranging the optical components without interfering with each other, it is difficult to produce a merit of downsizing.

  From the above, it is important for multi-function intensive optical devices to support multiple ports while taking advantage of low cost and downsizing. However, in order to reduce the crosstalk between the WSS function units, there is a request to reduce the beam diameter from the equation (2). On the contrary, to increase the number of ports as the WSS, the beam diameter is calculated from the equation (3). Since there is a demand for increasing the size, it is clear that the number of ports that can be realized is limited by the height of the spatial light modulator 207 in the y-axis direction, and a device configuration method that can overcome this limitation is eagerly desired.

  Therefore, the present invention aims at different designs for the wavelength dispersion of the optical function unit related to the first input / output port group and the wavelength dispersion of the optical function unit related to the second input / output port group. Accordingly, an object of the present invention is to provide an optical signal processing device capable of increasing the number of ports while reducing crosstalk between optical function units. Furthermore, the above-mentioned problems can be further solved by using AWG (Arrayed-waveguide grating) by PLC (Planar lightwave circuit), BRW (Bragg-reflector waveguide), which is a semiconductor distributed device, and the like as wavelength demultiplexing elements. An object of the present invention is to provide an optical signal processing apparatus capable of achieving economic efficiency.

In order to achieve such an object, a first aspect of the present invention is an optical signal processing device. The optical signal processing apparatus includes a first optical input / output unit and a second optical input / output unit having N (N is an integer of 1 or more) input / output ports, a first optical input / output unit, and the second optical input / output unit. A wavelength separating unit for wavelength-separating each of the wavelength multiplexed optical signals emitted from the input / output port of the optical input / output unit, a condensing unit for condensing the optical signals separated for each wavelength by the spectroscopic unit, Spatial light modulating means for optically modulating each of the optical signals collected by the means. Further, in the optical signal processing device, the spectroscopic means is configured to disperse the wavelength multiplexed optical signal emitted from the input / output port of the first optical input / output unit and the wavelength emitted from the input / output port of the second optical input / output unit. Different from the dispersion power for the multiplexed optical signal, the wavelength dispersion direction for the wavelength multiplexed optical signal emitted from the input / output port of the first optical input / output unit and the wavelength multiplexing output from the input / output port of the second optical input / output unit The wavelength-multiplexed optical signal emitted from the input / output port of the first optical input / output unit and the wavelength-multiplexed optical signal emitted from the input / output port of the second optical input / output unit are opposite to the wavelength dispersion direction with respect to the optical signal. Is characterized in that the order of arrangement of the converging positions of the optical signals dispersed for each wavelength from the short wavelength to the long wavelength in the chromatic dispersion direction in the spatial light modulator is different.

In one embodiment, the spectroscopic means may be an arrayed waveguide grating, a Bragg reflector waveguide or a grating coupler.

  As described above, according to the present invention, it is possible to provide an optical signal processing device capable of increasing the number of ports while reducing crosstalk between optical function units. Further, it is possible to achieve further miniaturization by using AWG (Arrayed-waveguide grating) by PLC (Planar lightwave circuit), BRW (Bragg-reflector waveguide), which is a semiconductor distributed device, and the like as wavelength demultiplexing elements. It is possible to provide an optical signal processing device that can be used.

It is a figure for demonstrating the structural example of a wavelength division multiplex node. It is a figure for demonstrating the concept of an optical signal processing apparatus, (a) is a block diagram of an optical signal processing apparatus, (b) is a block diagram of the simplified optical signal processing apparatus. It is a figure for demonstrating the crosstalk between the wavelength selection switch function parts of an optical signal processing apparatus, (a) is a side view of the optical signal processing apparatus shown in FIG.2 (b), (b) is a spatial light modulator. It is a figure for demonstrating the beam condensed on. It is a figure for demonstrating the concept of an optical signal processing apparatus, (a) is a side view of the optical signal processing apparatus shown in FIG.2 (b), (b) is the beam deflection angle set to a spatial light modulator. It is a figure for demonstrating. It is a figure which shows the structural example of the wavelength selection switch function part of an optical signal processing apparatus. It is a figure which shows the structure of the optical signal processing apparatus concerning one Embodiment of this invention, (a) is a top view, (b) is a side view. It is a figure which shows the optical signal processing apparatus concerning one Embodiment of this invention, (a) is a top view, (b) is a side view. It is a figure which shows the optical signal processing apparatus concerning one Embodiment of this invention, (a) is a top view, (b) is a side view. It is a figure which shows the optical signal processing apparatus concerning one Embodiment of this invention, (a) is a top view, (b) is a side view. It is a figure which shows the structure of the dispersion element of the optical signal processing apparatus concerning one Embodiment of this invention. It is a figure which shows the structure of the dispersion element of the optical signal processing apparatus concerning one Embodiment of this invention, (a) is sectional drawing, (b) is a top view.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of various embodiments, specific numerical examples are used. However, the present invention is not limited to such specific numerical examples, and the loss of generality is based on other numerical values. It goes without saying that can also be implemented. The same or similar reference numerals indicate the same or similar elements, and duplicate descriptions are omitted.

(Embodiment 1)
6A and 6B are diagrams showing the configuration of the optical signal processing apparatus according to the first embodiment of the present invention, where FIG. 6A is a plan view and FIG. 6B is a side view. The optical signal processing device according to the present embodiment is arranged in the subsequent stage of the first microlens array 602-1 disposed in the subsequent stage of the first input / output port group 601-1 and the second input / output port group 601-2. The second microlens array 602-2 thus arranged are arranged at different angles in the XZ plane, and a diffraction grating 603, a lens 604, and a spatial light modulator 605 are arranged in this order. In the description of the present embodiment, only one lens 604 is used as the lens. However, any number of lenses may be used as long as the configuration has similar optical characteristics, and any arrangement is used. There is no problem. Depending on the optical system design, a configuration in which the lens 604 is disposed between the microlens array 602 and the diffraction grating 603 is also possible. Further, for the purpose of reducing aberrations and shortening the optical system, a structure in which the lens 604 is composed of two lenses and the diffraction grating 603 is sandwiched between them can be adopted. Furthermore, in the present embodiment, a description is given assuming a combination of a fiber array 601 and a microlens array 602 as an interface between an optical fiber and a spatial optical system. However, if the configuration has similar optical characteristics, a microlens array is used. It is not always necessary to use a beam diameter adjusting mechanism (for example, an anamorphic prism pair) instead of a microlens array. Furthermore, as the interface, for example, an optical waveguide substrate represented by PLC may be used.

  In the description of this embodiment, it is assumed that the optical signals emitted from the first input / output port group 601-1 and the second input / output port group 601-2 are incident at a certain point on the diffraction grating 603. Yes.

  The operation of the optical signal processing apparatus of the present invention is as follows, taking as an example the functional units involved in the first input / output port group 601-1. First, the optical signal input to the first input / output port group 601-1 is emitted to the space as collimated light through the first microlens array 602-1. The signal light propagating in the space is wavelength-demultiplexed by the diffraction grating 603, collected by the lens 604, and condensed to the lower side with respect to the X-axis direction of the spatial light modulator 605 in FIG. . The light that has been subjected to the desired phase modulation and reflected by the spatial light modulator 605 is deflected to a desired angle in the YZ plane according to the phase setting, and further passes through the lens 604 again. Optical switching is performed at an arbitrary port, and the switching operation is completed. Since the optical signal related to the second input / output port group 601-2 is emitted to the space at an angle different from that of the optical signal related to the first input / output port group 601-1, in FIG. The light is condensed on the upper side with respect to the X-axis direction of the modulator 605. In other words, the diffraction grating has different dispersibility between the optical signal emitted from the first input / output port group 601-1 and the optical signal output from the second input / output port group 601-2. Here, the dispersibility refers to the direction of wavelength dispersion and the emission angle per unit wavelength. For example, the optical signals of each wavelength emitted from the first input / output port group 601-1 and separated are collected so as to be arranged in the order of short wavelength to long wavelength downward with respect to the X-axis direction of the spatial light modulator 605. Shine. On the other hand, the optical signals of the respective wavelengths emitted from the second input / output port group 601-2 and separated are collected so as to be arranged in the order of long wavelength to short wavelength downward with respect to the X-axis direction of the spatial light modulator 605. Shine. Therefore, since the optical signals related to the first input / output port group 601-1 and the second input / output port group 601-2 can be considered as independent optical systems, aggregation of a plurality of functions can be realized.

  In the present embodiment, the WSS function represented by the formula (2) is arranged by arranging the WSS function unit arranged in parallel in the Y-axis direction in FIG. 2 on the same X-axis as the wavelength demultiplexing axis. There is no need to consider crosstalk between the parts, and the diameter of w1 can be increased as shown in the equation (3), and the number of ports can be set to be twice or more that of the configuration in FIG.

  The description so far will be considered with specific numerical values. For each of the configuration shown in FIG. 3 and the configuration in the present embodiment, the crosstalk between WSS function units according to Equation (2) and the crosstalk between ports according to Equation (3) are suppressed to −40 dB or less, respectively, and spatial light The usable height (length) H of the modulator is set as 2 * w1 + 2 * w2 + Δy ≦ 15000 μm. For simplification of calculation, the calculation is performed with w1 = w2 and the maximum deflection angle by the spatial light modulator as 1 deg. In the optical signal processing apparatus having the configuration as shown in FIG. 3, Δy / w1 = 3.05 is derived from Equation (2), and w1 is calculated to have an upper limit of about 2100 um from the height limitation of the spatial light modulator. When the beam radius w1 is determined, Δθ for securing the crosstalk between ports of −40 dB or more is calculated from the equation (3) to be 0.041 deg. Consequently, in the configuration of the optical signal processing device of FIG. It can be seen that 1 deg / 0.041 deg = 24 ports is the upper limit. On the other hand, since the restriction on the number of ports according to the expression (2) is eliminated in the present embodiment, w1 can be set larger than that of the conventional configuration and can be designed as w1 = about 3700 μm. From equation (3), it is estimated that Δθ = about 0.023 deg in this case, and as a result, 43 ports can be realized. Therefore, by applying this embodiment, the number of ports can be increased by about twice that of the conventional configuration.

  The present embodiment not only contributes to the increase in the number of ports as described above, but also can improve the manufacturing cost for realizing the optical device. Among the lens and the input / output port group, the first input / output port group 601-1 and the second input / output port group 601-2 are set so that the installation angles are not parallel but have a finite value. It is characterized in that it is not necessary to divide a plurality of parts in the X-axis direction. The lens is a Fourier transform element and has a function of mutually converting the position and angle of incident light. Therefore, in order to collect light at different positions on the spatial light modulator 305 for each WSS functional unit, it is necessary to change the angle of each other at the front stage of the lens. By adjusting the installation angle of the input / output port group and the microlens array in this way, as shown in FIG. 2, multiple functions are integrated with only one lens without separately arranging the lenses for each WSS function unit. An optical device can be realized, and the cost can be reduced by reducing the number of members, and the manufacturing throughput can be improved by facilitating alignment. Further, in the configuration of FIG. 2B, the light passing through the diffraction grating 205 is widely distributed in the arrangement direction of the WSS function unit (the Y-axis direction in FIG. 2B), so that no vignetting occurs. Therefore, it is necessary to prepare a sufficiently large diffraction grating. Among many optical elements, the diffraction grating belongs to an expensive class, and its price is proportional to the area. In view of this point, in this embodiment, by adopting a configuration in which the diffraction grating is arranged at a certain point where the principal rays of each WSS functional unit intersect on the XZ plane, the area of the diffraction grating is reduced to about half of the conventional one. This can be suppressed and further cost cut is possible. As described above, the present embodiment solves the above-described problems, and can realize an optical signal processing device that is low in cost and good in mountability.

  In the above embodiment, the dispersion power of the diffraction grating differs between the optical signal output from the first input / output port group 601-1 and the optical signal output from the second input / output port group 601-2. Even if the number of input / output port groups is three or more and the diffraction gratings are configured so that the optical signals emitted from at least one input / output port group have different dispersion powers, crosstalk can be reduced.

(Embodiment 2)
7A and 7B are diagrams showing the configuration of the optical signal processing apparatus according to the second embodiment of the present invention, where FIG. 7A is a plan view and FIG. 7B is a side view.

  As shown in FIG. 7, the basic configuration of the optical signal processing device according to the present embodiment is the first microlens array 602 disposed in the subsequent stage of the first input / output port group 601-1 as in the first embodiment. -1 and the second microlens array 602-2 arranged in the subsequent stage of the second input / output port group 601-2 are arranged at different angles in the XZ plane, and further, the diffraction grating 603, the lens 604 and the spatial light modulator 605 are arranged in this order. In the first embodiment, optical signals emitted from the first input / output port group 601-1 and the second input / output port group 601-2 are diffracted. The point which injects into the different position on the grating | lattice 603 differs in the point to which the angle correction member 701 is added in connection with this.

  In the configuration in the first embodiment, the optical signal emitted from each of the first input / output port group 601-1 and the second input / output port group 601-2 is designed to enter a certain point on the diffraction grating 603. Therefore, by arranging this incident point at the focal position of the lens 604, the optical device is configured such that light of all wavelengths is incident vertically (telecentric optical system) toward the spatial light modulator 605. Was possible. However, since a region where no signal light is incident is formed at the central portion of the spatial light modulator 605, it is desirable to apply a large area as a requirement for the spatial light modulator 605. In the present embodiment, the optical signal emitted from each of the first input / output port group 601-1 and the second input / output port group 601-2 is incident on different positions on the diffraction grating 603, so that the lens 604 The main difference from the first embodiment is that the first WSS function unit and the second WSS function unit are brought close to each other by shifting from the focal position.

  In the present embodiment, as described above, the incident angle of the signal light incident on the spatial light modulator 605 does not become vertical due to the effect that the incident position on the diffraction grating 603 is shifted from the focal position of the lens 604. Therefore, it is desirable to introduce an angle correction member 701 between the lens 604 and the spatial light modulator 605 so that this angular change is corrected and a telecentric optical system is established in the spatial light modulator 605. The angle correction member is exemplified in the present embodiment as a triangular prism shape that is an isosceles triangle in the XZ plane, but may be any shape as long as the same optical characteristics can be realized. In addition, there is no problem even if the angle correction member 701 is disposed between the lens 604 and the diffraction grating 603. Furthermore, when the spatial light modulator 605 can also perform phase modulation in the X-axis direction, by applying a phase change equivalent to the phase change caused by the angle correction member 701 to the signal light by the spatial light modulator 605, The angle correction member 701 can be omitted. In this case, it is not necessary to prepare the angle correction member 701 separately, and further cost reduction can be expected.

  For Example 2, as shown in FIG. 8, the first input / output port group 601-1 and the first microlens array 602-1, the second input / output port group 601-2 and the second microlens array 602-2. It is also possible to arrange each of the combinations so as to have different traveling directions in the yz plane. In this case, the spatial light modulator 605 is designed so that the wavelength demultiplexing region has the same coordinate in the x-axis direction. In this case, as shown in FIG. 3, the pitch between the WSS function units Δy is set small. However, in the configuration described in FIG. 8 of the second embodiment, the directions of wavelength demultiplexing in the first WSS function unit and the second WSS function unit are opposite to each other. Clearly different. In this case, focusing only on a certain wavelength demultiplexed by the diffraction grating 603, the light is condensed at different coordinates with respect to the x-axis on the spatial light modulator 605. Also, -40 dB can be secured. In the configuration in FIG. 8, the diffraction grating tends to have a larger area than the configuration in FIG. 7, but by reducing the length of the spatial light modulator 605 in the x-axis direction, the small area of the spatial light modulator 605 is reduced. Can be achieved. Furthermore, since the length in the x-axis direction of the wavelength demultiplexing region that can be assigned to each WSS function unit by the spatial light modulator 605 can be improved, the optical signal processing device in FIG. 8 has excellent wavelength resolution. It will have characteristics.

  In the present embodiment, the area of the spatial light modulator 605 can be reduced while maintaining the optical characteristics that can be realized by the optical device in the first embodiment. As the spatial light modulator, a liquid crystal cell array, MEMS, LCOS, or the like is generally used. However, the spatial light modulator has a size that can be realized due to in-plane stability and technical limitations of a large CMOS manufacturing process. There is a limit. For this reason, by improving the in-plane utilization of the spatial light modulator, it is possible to realize a small-sized but multi-port optical device.

(Embodiment 3)
FIG. 9 is a diagram showing the configuration of a third embodiment of the optical signal processing device according to the present invention. Yes, (a) is a plan view and (b) is a side view.

  As shown in FIG. 9, the basic configuration of the optical signal processing device according to the present embodiment includes a first cylindrical lens array 802-1 arranged at the rear stage of the first input / output port group 801-1, and a second input. The second cylindrical lens array 802-2 arranged in the subsequent stage of the output port group 801-2 is arranged so as to emit light at different angles in the XZ plane, and the lens 803, the angle correction member 804, and the spatial light. The modulator 805 is arranged in this order. In the first and second embodiments, the input / output port is arranged in the dispersive element array 801, and is a member having a wavelength dispersion function instead of a general bulk diffraction grating. It is different in the configuration. The first input / output port and the second input / output port in each dispersion element forming the dispersion element array 801 form a first input / output port group 801-1 and a second input / output port group 801-2, respectively.

  FIG. 10 shows details of the dispersive element array 801 in FIG. As shown in FIG. 10, each of the dispersive elements constituting the dispersive element array 801 includes a slab waveguide group 902 connected to the first optical waveguide 901-1 and a first array waveguide connected to the slab waveguide group. 903-1 and a first slab waveguide 904-1 connected to the first array waveguide, and in addition, a slab waveguide group 902 connected to the second optical waveguide 901-2, and a slab waveguide group And a second slab waveguide 904-2 connected to the second arrayed waveguide. This configuration is the same as the AWG that is most commonly used when the optical waveguide circuit has a wavelength demultiplexing function. The dispersion element array 901 is formed by stacking the optical waveguide circuits in the y-axis direction. The slab waveguide group 902 promotes the miniaturization of the dispersive element array 801 by sharing the optical waveguide circuit related to each of the first WSS function unit and the second WSS function unit. As shown, the slab waveguide related to the first WSS functional part and the slab waveguide related to the second WSS functional part are separated and arranged according to the request from the circuit layout and other functional circuits formed in the dispersion element 801. There is no problem at all. The first slab waveguides 904-1 and 904-2 may or may not be provided depending on the request from the spatial optical design.

  The basic operation principle is the same as that of the second embodiment described with reference to FIG. 7, but the input / output port group 601, the microlens array 602, and the diffraction grating 603 in the second embodiment are included in the demultiplexing element array 801. The significance of this embodiment exists in terms of function integration. The feature of the optical signal processing apparatus using the spatial optical system is the degree of freedom in three-dimensional optical signal processing and optical design. By designing the spatial light modulator 605 independently of the chromatic dispersion axis and the optical deflection axis, a wavelength selective switch can be realized by combining the functions of both in one device. On the other hand, the adjustment of the beam diameter tends to cause an additional cost for arrangement of lenses and alignment in mounting. Depending on the optical design, the lens arrangement becomes a problem, and the total length of the device tends to be long. Furthermore, when controlling the beam diameter in the XZ plane, there is a possibility that the desired beam diameter may not be achieved only by adopting a microlens array. To overcome this problem, additional members such as an anamorphic prism pair are used. Need to be placed. On the other hand, when the functions are integrated in the dispersive element array 801 as in this embodiment, the same mounting accuracy as that of photolithography can be realized without alignment and mounting, and the cost can be greatly reduced. Further, the AWG can take a large difference in waveguide length between the arrayed waveguides, and can generally have a dispersibility that is several to ten times that of a bulk type diffraction grating. In an optical signal processing apparatus employing a spatial optical system, this feature can be designed with the optical length of the entire device, that is, the lens 803 having a short focal length, and is extremely important in terms of miniaturization of the device. have.

  As described above, as the means for realizing the dispersion element array 801, the laminated array waveguide grating as shown in FIG. 10 is exemplified. However, any dispersion element array having a similar function may be used. It is not restricted to such a structure. As long as the device has a dispersion element function, for example, a dispersion element called a virtually imaged phased array (VIPA), a grating coupler, and other similar devices can be used as the dispersion element array 801.

  FIG. 11 shows an example of these dispersive elements that can be used as the dispersive element array 801. FIG. 11 is a configuration diagram of a Bragg reflector waveguide (BRW) that can be used in place of the dispersion element array 801 used by the AWG. FIG. 11A is a cross-sectional view, and FIG. 11B is a top view. According to FIG. 11A, the BRW dispersion element array includes a waveguide input / output port 1003 for coupling signal light emitted from the fiber array 1001 and the microlens array 1002 to the dispersion element array, and a substrate vertical direction. The upper reflecting mirror 1004, the lower reflecting mirror 1005, and the waveguide layer 1006 are provided. The waveguide layer 1006 includes an active region that is sandwiched between upper and lower light confinement layers. The signal light coupled from the waveguide input port 1003 to the substrate repeats multiple reflections geometrically and optically between the upper reflecting mirror 1004 and the lower reflecting mirror 1005. The distance between the reflecting mirrors in the vertical direction is about the wavelength, that is, about 1 μm. At this time, since the reflectivity of the upper reflector is designed to be lower than the reflectivity of the lower reflector, when propagating through the waveguide in a zigzag manner, a part of the light from the reflector having a low reflectivity enters the space. Emitted. At the time of emission, since different refraction angles are provided for each wavelength in accordance with Snell's law, the light is emitted to space at different angles for each wavelength of the input WDM optical signal. That is, in the BRW shown in FIG. 11, each waveguide layer 1006 forms a wavelength demultiplexing function unit, and operates as a dispersion element array 801, that is, a wavelength demultiplexing element. In this embodiment, the total number of optical fibers of the input / output fiber array 1001 is described as six (each WSS function unit has three ports, so each WSS function unit has three ports). The wavelength demultiplexing function units 1006-1 to 1006-3 are arranged so as to correspond to the number of the wavelength demultiplexing function units 1006-1 to 1006-3, one at each end of the wavelength demultiplexing function unit in the x-axis direction. In FIG. 11, the first input / output fiber array 1001-1 and the first microlens array 1002-1 related to the first WSS function unit are on the right side of the page, and the second WSS function unit on the left side of the page. A two-input / output fiber array 1001-2 and a second microlens array 1002-2 are arranged. Each wavelength demultiplexing function unit is optically independent. In order to reduce crosstalk between adjacent wavelength demultiplexing function units, it is desirable to provide a light blocking layer between the wavelength demultiplexing function units. For example, although groove formation by etching is considered as one of the means, there is no problem in any form as long as the same function is realized.

At this time, the incident angle to the upper reflecting mirror 1004 is θ _i , the exit angle to the space is θ, the equivalent refractive index of the waveguide constituting the demultiplexing angle disperser is n _wg , and the refractive index of _air is n _air (= 1), n _air × sin θ = n _wg × sin θi is obtained according to Snell's law, and when the cutoff wavelength of the waveguide is λ _c and the wavelength used is λ, the refraction angle is given by the following relational expression: expressed.

  Therefore, in this wavelength demultiplexing element, the angle θ at which the designed cutoff wavelength λc travels can be regarded as the basic traveling direction of the signal light, and the light having the wavelength λc behaves to travel at this angle.

  At this time, since the BRW has a uniform structure in the x-axis direction, it is possible to couple the fiber from the right side (waveguide input / output port 1003-1) in the x-axis direction. A fiber can also be coupled from the waveguide input / output port 1003-2). Due to the difference in the incident direction, the emission angle of the optical signal to the space can be controlled by ± θ, and the same operation as in FIG. 9A can be performed. FIG. 11A illustrates propagation of an optical signal incident from the waveguide input / output port 1003-1 in the first WSS function unit and emission to space, and light incident from the waveguide input / output port 1003-2. The propagation of the signal with respect to the second WSS function part and the emission to space are not shown.

  When the BRW described with reference to FIG. 11 is used as the dispersive element array 801, it can have the same level of dispersibility as AWG and is very effective for miniaturization. Further, with respect to the present BRW, a plurality of BRWs can be manufactured collectively using a waveguide manufacturing process. The laminated AWG needs to be polished each time a waveguide layer is formed, smoothed, and then subjected to the waveguide process again. The process load increases as the number of ports increases. In BRW, the required number of wavelength dispersion elements can be formed in a single process, so the cost involved in manufacturing can be kept very low, and the multi-function intensive optical signal is an important merit in reducing costs. The characteristics of the processing apparatus can be further utilized.

DESCRIPTION OF SYMBOLS 101,106 Wavelength selective switch (WSS) group 102 Wavelength demultiplexing function part group 103 Receiver group 104 Transmitter group 105 Wavelength multiplexing function part group 107 Wavelength cross-connect function part 201,501,601,801 Input / output port group 202 , 502, 602 Micro lens array 203 Lens group 204, 206, 504, 604, 803 Lens 205, 503, 603 Diffraction grating 207, 505, 605, 805 Spatial light modulator 701, 804 Angle correction member 802 Cylindrical lens array 901 Light Waveguide 902, 904 Slab waveguide group 903 Array waveguide 1001 Fiber array 1002 Micro lens array 1003 Waveguide input / output port 1004 Upper reflecting mirror 1005 Lower reflecting mirror 1006 Waveguide layer

Claims (4)

A first optical input / output unit and a second optical input / output unit having N (N is an integer of 1 or more) input / output ports, and the first optical input / output unit and the second optical input / output unit A wavelength separating unit for wavelength-separating each of the wavelength-multiplexed optical signals emitted from the input / output ports, a light collecting unit for condensing the optical signals separated for each wavelength by the light separating unit, and a light collecting unit by the light collecting unit. Spatial light modulating means for optically modulating each of the emitted optical signals,
The spectroscopic unit is configured to disperse a wavelength multiplexed optical signal output from the input / output port of the first optical input / output unit and to disperse a wavelength multiplexed optical signal output from the input / output port of the second optical input / output unit. The wavelength dispersion direction for the wavelength multiplexed optical signal emitted from the input / output port of the first optical input / output unit and the wavelength multiplexed optical signal emitted from the input / output port of the second optical input / output unit. the wavelength dispersion direction and a reverse, wavelength-multiplexed optical signal emitted from the first output port of the wavelength-multiplexed optical signal and the second light output section emits the output port of the optical input-output unit and Then, the optical signal processing apparatus is characterized in that the arrangement order of the light collecting positions from the short wavelength to the long wavelength in the wavelength dispersion direction in the spatial light modulation means of the optical signals dispersed for each wavelength is different. 2. The optical signal processing apparatus according to claim 1 , wherein an arrayed waveguide diffraction grating is used as the spectroscopic means. The optical signal processing apparatus according to claim 1 , wherein a Bragg reflector waveguide is used as the spectroscopic means. The optical signal processing apparatus according to claim 1 , wherein a grating coupler is used as the spectroscopic means.

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