JP2017156444A - Wavelength selective switch and optical node device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a WSDM optical node device using a smaller number of wavelength selective switches.SOLUTION: The wavelength selective switch comprises a position angle conversion unit, a port selective lens, and a switch element. The position angle conversion unit comprises a conversion portion that has an input/output port by the number of cores of an SDM fiber for each SDM fiber. The conversion portion comprises: each input/output port at a position corresponding to each core of the SDM fiber; and means that outputs an optical signal to be input into the input/output port at an angle corresponding to the position of the input/output port. A surface reflecting the optical signal in the switch element has a divided area divided for each core of the SDM fiber, and the optical signal input into the input/output port having the conversion portion corresponding to the input SDM fiber is converged to the divided area corresponding to the core associated with the position of the input/output port, and the optical signal reflected from the divided area reaches the conversion portion corresponding to the SDM fiber for the optical signal to be output.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a technique for realizing an optical node device constituting a wavelength multiplexing / spatial multiplexing optical network that controls a path according to wavelength information and spatial information of an optical signal.

  In general, the transmission capacity of a transmission line can be increased by increasing either or both of the transmission band and the signal-to-noise ratio. Currently, an optical fiber widely used in a long-distance optical fiber network has one single-mode core formed in one optical fiber. This is called a single mode fiber (SMF), and its cross section is shown in FIG. When SMF is used for a transmission line, waveform distortion due to the nonlinear optical effect in the core of the optical fiber becomes significant when the transmission light power is increased more than a certain value in order to increase the signal-to-noise ratio. For this reason, there is an upper limit to the transmission optical power, and therefore, the capacity of one SMF has a physical limit, and it is considered that the total capacity is about 1 Pb / s in the long-distance transmission application. On the other hand, the total capacity of the latest long-distance optical fiber communication system has already reached 100 Tb / s, and considering the increasing trend of Internet traffic, there is a common recognition that a new optical fiber technology to replace the current single mode fiber is necessary. It has been brewed (Non-patent Document 1).

  As a new optical fiber, an optical fiber bundle (FB: Fiber Bundle) using a plurality of SMFs bundled together, a single optical fiber having no inter-core coupling (practically small inter-core coupling is negligible). An uncoupled multi-core fiber (UC-MCF) (Fig. 1 (b)) with a single-mode core, and a fu-mode fiber (FMF) that can propagate several propagation modes with a single core. Few Mode Fiber (FIG. 1 (c)), coupled core fiber (CCF) that can propagate a plurality of super modes by a plurality of closely arranged single mode cores (FIG. 1 (d)) , And their combined structures (FIGS. 1E and 1F) have been proposed. Since these optical fibers multiplex information in the direction of the spatial axis, they are generically referred to as Spatial Division Multiplexing (SDM) fibers. The SDM fiber can transmit the number of optical channels represented by the product of the number of wavelengths and the number of propagation modes.

  SDM fibers are classified into two types, a non-coupling type and a coupling type, depending on the presence or absence of coupling between propagating spatial modes. When there is coupling between propagation modes, crosstalk occurs between optical channels that have the same wavelength but different propagation modes.In this case, multiple mixed-wavelength optical channels are mixed in multiple-input multiple-output MIMO (MIMO). ) Separated by processing. FB and UC-MCF are classified as unbound, and FMF and CC-MCF are classified as bound. In the future, it is expected that wavelength multiplexing / spatial multiplexing (WSDM) optical networks using a combination of multiplexing of the spatial axis in addition to the conventional wavelength axis will play an important role.

  In such an optical node device of the WSDM optical network, a plurality of optical channels propagated by spatial multiplexing and wavelength multiplexing of optical links connected to the optical node device are once separated, and routes are distributed according to the final destination. There is a need to provide multiplexing, demultiplexing, and path distribution functions in the wavelength axis and space axis that are multiplexed onto an appropriate optical link. An apparatus having such a function is called a wavelength division multiplexing / spatial multiplexing node apparatus (WSDM optical node apparatus). A wavelength selective switch (WSS: Wavelength Selective Switch) is widely used as a component in an optical node device of a current wavelength division multiplexing optical network. Therefore, in the WSDM optical network, it is considered that a wavelength selective switch for spatial multiplexing (SDM-WSS), which is based on WSS and expanded on the spatial axis, is a key device.

  For reference, FIG. 2 shows a configuration example of an optical node device provided with a conventional WSS for a single mode fiber. In FIG. 2 and subsequent configuration diagrams, the left side of the figure is the input side, and the right side is the output side. The input optical signal is a wavelength-multiplexed signal. In the case of FIG. 2, the number of fibers (N) is 3, the number of modes (m) is 1, and a WSS with 1 input N outputs for each fiber is provided on each of the input side and the output side.

  Next, a description will be given of a WSDM optical node configuration for a non-coupled SDM fiber when a conventional single mode WSS is used. WDM-SDM optical node equipment that is expanded for the SDM fiber of the Route and Select structure used for the conventional single mode fiber, considering that the uncoupled SDM fiber is a conventional single mode fiber arranged in parallel As a configuration, the configuration shown in FIG. 3 can be considered. In this configuration, if N is the number of SDM fibers (for FB, the fiber bundle is counted as one), and the number of spatial modes (number of single mode cores) that one SDM fiber propagates is m, one input Nm output 2Nm of single mode WSSs are required.

  The configuration shown in FIG. 3 shows a configuration when N = 3 and m = 4, and Nm = 12 single-input Nm (12) output single-mode WSSs are required on the input side and the output side, respectively. Has been shown to be. In this configuration, any wavelength of any spatial mode in any input SDM fiber can be connected to any spatial mode in any output SDM fiber.

  FIG. 4 shows a configuration using a 1-input N-output WSS (an example where N = 3 and m = 4). For example, if a number is assigned to the spatial mode of an SDM fiber, any input SDM fiber Any wavelength in any spatial mode can be connected to the same numbered spatial mode in any output SDM fiber. In this case, connection to different spatial modes is impossible. However, considering that all spatial modes propagating through one SDM fiber are connected to the same adjacent optical node, there is no problem in practical use. be able to. The required number of WSSs with 1 input and N outputs is 2Nm, and the WSS is required to be 2 times the number of WSSs required for the optical node for the conventional single mode optical fiber shown in FIG.

  Next, the configuration of the WSDM optical node for the coupled SDM fiber will be described. In the coupled SDM fiber, a part of the energy of the optical channel transmitted in a certain spatial mode at the input end shifts to another spatial mode, so that the optical signal of each spatial mode at the output end is a component of a plurality of optical channels. It becomes a mixture of. The optical channels mixed as described above are finally separated by MIMO processing at the receiving end. In general, since the power distribution of the spatial mode in the coupled SDM fiber is different for each mode, in order to obtain uniform wavelength transmission characteristics regardless of the spatial mode, the optical signal propagating in the SDM fiber is spatially limited by the number of spatial modes m. And the sampled optical signal is input to m single-mode fibers. Since the coupled SDM fiber needs to perform MIMO processing at the receiving end, all spatial modes of a certain wavelength in the same SDM fiber are transferred from the same transmitting end to the same receiving end. For this reason, if it is possible to switch all the spatial modes with a single optical switch element for a certain wavelength in the SDM fiber, the cost of the optical switch element can be shared by a plurality of optical channels. It is possible to reduce the switching cost.

  As such a configuration, a WSS having the configurations of FIGS. 5 and 6 has been proposed (Non-Patent Documents 2 and 3).

  In the configuration shown in FIG. 5, in the WSS having the total number of ports of (N + 1) m, m ports are used as input ports, the remaining Nm ports are used as output ports, and m input Nm output WSSs are used.

  By inputting m single-mode fibers to which the spatially sampled optical signals described above are input to m-input Nm-output WSS and adjusting the angle of a single switching element, all the single SDM fibers in the same SDM fiber are adjusted. The optical channels can be collectively connected to the target output SDM fiber. Such a technique is called wavelength joint switching.

  FIG. 5 shows a case where m = 3 and N = 2, and optical signals of each mode (1 to 3) are input through three single mode fibers, and output to the output port of OUT1, for example. ing. FIG. 6 shows a configuration in which input single-mode fibers are shuffled and connected, whereby the change in angle required for the switching element can be reduced.

  FIG. 7 shows a configuration of a WSDM optical node device using m-input Nm-output WSS. This configuration uses the WSS that performs wavelength coupling switching shown in FIGS. 5 and 6. The device indicated by 10 in FIG. 7 is an MM-SM converter (converter) that converts a multimode optical signal into a single mode equivalent to the number of spatial modes.

  If this configuration is used, the number of WSSs can be reduced to 2N. However, the required total number of ports increases to (N + 1) m. As a WSS configuration that realizes multi-port wavelength-coupled switching, a configuration in which input ports that are conventionally arranged one-dimensionally are arranged two-dimensionally has been proposed (Non-Patent Document 4).

  Moreover, as shown in FIG. 8, the structure which performs wavelength coupling switching for every group to couple | bond is also possible.

  In the current large-scale WDM optical network, the loss of the optical fiber is compensated by an optical amplifier installed at every fixed distance. The amplification factor of the optical amplifier depends on each wavelength, and it is difficult to make the amplification factor of the optical amplifier for each optical channel completely uniform. The power deviation of the optical channel is accumulated every time it passes through the optical amplifier. For this reason, the power deviation is adjusted to be uniform by the WSS constituting the WDM optical node device. In a WSDM optical network, the transmission loss of the optical channel of each spatial mode is compensated by an optical amplifier, but as with the wavelength dependence of the amplification factor, it is impossible to make the amplification factor for each spatial mode completely uniform. It is considered difficult. It is also considered that the spatial mode dependence of the loss of connectors, splicing and other optical devices is also affected.

  In the configurations shown in FIGS. 5 and 6, since all optical signals input from m single-mode fibers are switched by adjusting the angle of one optical switching element, the output light is adjusted by adjusting the angle. Even if the coupling ratio to the port can be adjusted at the same time, the coupling ratio is individually adjusted for each optical signal, and the output optical power cannot be made uniform. However, in a coupled SDM fiber, since there is strong coupling between spatial modes as the fiber propagates, each optical channel propagates in a plurality of spatial modes. For this reason, the spatial mode-dependent loss is greatly reduced, and power adjustment for each spatial mode is unnecessary. On the other hand, in the uncoupled SDM fiber, there is no coupling between such spatial modes, and the optical power deviation between the optical channels accumulates. For example, all the optical channels in a certain input optical fiber are connected to the same output light. Even when connected to a fiber, wavelength coupling switching cannot be used because power deviation adjustment is required.

P. J. Winzer, "Scaling optical fiber networks: challenges and solutions," OPTICS & PHOTONICS NEWS, March 2015, pp. 28-35. M. D. Feuer, et al., "ROADM system for space division multiplexing with spatial superchannels," OFC 2013, PDP5B.8. N. K. Fontaine, et al., "Few-mode fiber wavelength selective switch with spatial-diversity and reduced-steering angle," OFC 2014, Th4A.7. N. K. Fontaine, et al., "Heterogeneous space-division multiplexing and joint wavelength switching demonstration," OFC 2015, Th5C.5. T. Mizuno, et al., "12-core × 3-mode dense space division multiplexed transmission over 40 km according multi-carrier signals with parallel MIMO equalization," OFC 2014, Th5B.2. R. Ryf, et al., "Space-division multiplexed transmission over 3 × 3 coupled-core multicore fiber," OFC 2014, Tu2J.4, 2014K. K. Suzuki, et al., "Ultra-high port count wavelength selective switch coated waveguide-based I / O frontend," OFC 2015, Tu3A.7. Y. Ikuma, et al., "8 × 24 wavelength selective switch for low-loss transponder aggregator," OFC 2015, Th5A.4. N. Nemoto, et al., "8 × 8 wavelength cross connect with add / drop ports integrated in spatial and planar optical circuits," ECOC 2015, Tu.3.5.1.

  As described above, when a WSDM optical node device is constructed with a Route and Select configuration for N pairs of uncoupled SDM fibers providing m spatial modes (eg, FIG. 4), a conventional one-input N The output single mode WSS needs 2Nm. This WDM optical node device can set m spatial mode paths per fiber, but the required number of WSSs is m times that of 2N conventional WDM optical nodes (eg, FIG. 2). 2Nm. The number of WSSs required per spatial mode is 2N, and there is a problem that the transfer cost per bit is not reduced. Wavelength coupled switching cannot be employed because there is no coupling between the spatial modes.

  On the other hand, for a coupled SDM fiber, the number of WSSs can be reduced to 2N by constructing a WSDM optical node using m-input Nm-output WSS by a wavelength-coupled switching technique (example: FIG. 7). However, the number of wavelength-coupled switching WSSs has increased for SDM fibers that have been proposed to further increase the number of spatial modes that can be propagated with a single fiber, and that combine the coupled and uncoupled types. (Example: FIG. 8). In such an SDM fiber, a plurality of multimode cores in which a plurality of spatial modes propagate are arranged so that there is no power coupling (FM-MCF (Few Mode Multi-Core Fiber)) (Non-Patent Document 5) (FIG. 1 (e)). GCC-MCF (Grouped Coupled Core Multi-Core Fiber) (Non-Patent Document 6) (FIG. 1 (f)) in which a plurality of adjacent single-mode core groups are arranged so that there is no power coupling. is there. In this case, the number of WSSs increases by the number of multimode cores or the number of combined single core groups.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a technique for realizing a WSDM optical node device using a smaller number of WSSs.

According to the present invention, there is provided a wavelength selective switch in an optical node device constituting a WSDL optical network,
A position angle conversion unit, a port selection lens, and a switch element;
The position angle conversion unit includes a conversion part having input / output ports for the number of cores of the SDM fiber for each SDM fiber connected to the wavelength selective switch,
The conversion portion includes input / output ports at positions corresponding to the cores of the SDM fiber, and optical signals input to the input / output ports at an angle corresponding to the positions of the input / output ports. Means to output to the side,
The surface of the switch element that reflects the optical signal has a divided region divided for each core of the SDM fiber,
The optical signal input to the input / output port having the conversion site corresponding to the input SDM fiber is condensed on the divided region corresponding to the core corresponding to the position of the input / output port and reflected from the divided region. A wavelength selective switch is provided, wherein the optical signal is configured to reach a conversion site corresponding to the SDM fiber from which the optical signal is output.

  According to the present invention, it is possible to provide a technique for realizing a WSDM optical node device using a smaller number of WSSs.

It is a figure which shows the example of an optical fiber. It is a figure which shows the structural example of the conventional optical node apparatus. It is a figure which shows the structural example of a WDM-SDM optical node apparatus. It is a figure which shows the structural example of a WDM-SDM optical node apparatus. It is a figure for demonstrating the structure of WSS. It is a figure for demonstrating the structure of WSS. It is a figure which shows the structural example of a WDM-SDM optical node apparatus. It is a figure which shows the structural example of a WDM-SDM optical node apparatus. It is a block diagram of the optical node apparatus in embodiment of this invention. 1 is a configuration diagram of a WSS of Example 1. FIG. It is a block diagram of the existing WSS including a wavelength surface and a switch surface. It is a figure for demonstrating LCOS. 1 is a configuration diagram of a WSS of Example 1. FIG. It is a figure which shows the structural example 1 of a position angle conversion part. It is a figure which shows the structural example 2 of a position angle conversion part. FIG. 4 is a configuration diagram of a WSS according to a second embodiment. FIG. 4 is a configuration diagram of a WSS according to a second embodiment. FIG. 6 is a diagram for explaining a configuration of a WSS according to a second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiment described below is only an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

(Configuration of optical node equipment)
FIG. 9 is a configuration diagram of the optical node device 100 according to the embodiment of the present invention. The optical node device 100 is an optical node device constituting a wavelength division multiplexing / spatial multiplexing (WSDM) optical network, and may be referred to as a WSDM optical node device, a WDM-SDM optical node device, or the like. By connecting a plurality of the optical node devices with optical fibers, a wavelength division multiplexing / spatial multiplexing (WSDM) optical network can be realized.

  As shown in FIG. 9, the optical node device 100 is provided with WSSs (wavelength selective switches) corresponding to the number of connected SDM fibers on each of the input side and the output side. For example, if the number of input SDM fibers and the number of output SDM fibers are four, four WSSs are provided on the input side, and four WSSs are provided on the output side. In this case, each WSS on the input side has four output ports, and each output port is connected to one WSS on the output side by a fiber or the like.

  As shown in FIG. 9, each output port of the WSS 101 is connected to one WSS on the output side. That is, the WSS 101 is connected to the WSSs 105 to 108. Although not shown, the same applies to the WSSs 102, 103, and 104.

  In the configuration of FIG. 9, the WSSs 101 to 104 on the input side may be replaced with a 1 to N optical splitter that divides the optical signal power from the SDM fiber into the number N of output side WSSs (N = 4 in this case). Good. Similarly, in the configuration of FIG. 9, the output-side WSSs 105 to 108 may replace N SDM fibers with N-to-1 optical couplers that are power-coupled to one SDM fiber.

  The type of SDM fiber used in the optical node device 100 is not limited, and any of the SDM fibers shown in FIG. 1 can be used.

  Below, the detailed structure of WSS is demonstrated as Example 1 and Example 2. FIG.

Example 1
FIG. 10 is a configuration diagram of the WSS of Example 1 configuring the optical node device 100 according to the present embodiment. In the following, the WSS on the input side will be described, but the WSS on the output side can also be realized with the same configuration. The WSS on the output side corresponds to a reverse operation of the optical signal connection operation described below.

  Here, the WSS is composed of a wavelength plane that is wavelength-separated by a diffraction grating and a switch plane in which ports are arranged. The WSS in this embodiment is characterized by a switch plane, and the existing technology is used for the wavelength plane. Therefore, a configuration diagram of the switch surface is shown as a configuration diagram of the WSS. As a reference, FIG. 11 shows a configuration showing both the wavelength plane and the switch plane in the existing WSS (Non-Patent Document 7). The WSS in the present embodiment can take, for example, the configuration shown in FIG. 11 as the configuration of the wavelength plane.

  The WSS of the first embodiment shown in FIG. 10 is a WSS for an uncoupled multicore fiber (UC-MCF). In the first embodiment, the uncoupled multi-core fiber (hereinafter referred to as fiber) has four cores, and each core propagates an optical signal in a single spatial mode. Hereinafter, the “space mode” is referred to as “mode”.

  As shown in FIG. 10, the fiber connected to the input side of the WSS is shown as fiber COM, and the four fibers connected to the output side of the WSS are shown as fiber A, fiber B, fiber C, and fiber D. ing.

  The WSS includes a connection unit 50, a position-angle conversion unit 20, a port selection lens 30, and an LCOS 40.

  The connection unit 50 is a device that connects each core of each fiber to a single mode fiber. The single mode fiber corresponding to each core is connected to the position-angle converter 20. The optical signal output from each core of the fiber COM by the device is input to the position-angle conversion unit 20 through the corresponding single mode fiber. The optical signal output from the position-angle conversion unit 20 to the fiber side is input to each core of the fibers A to D by the single mode fiber corresponding to each core of the fibers A to D.

  In the example shown in FIG. 10, the position-angle conversion unit 20 is a device integrated by an optical waveguide (PLC: planar lightwave circuit). More specifically, the position-angle conversion unit 20 has a portion corresponding to each fiber. In the example of FIG. 10, the letters COM and A to D are written in the portions of the position-angle conversion unit 20 corresponding to the fibers COM and A to D, respectively. Hereinafter, for example, when referring to the part of the position-angle conversion unit 20 corresponding to the fiber COM, the position-angle conversion unit 20COM (or simply 20COM) may be described. The same applies to the fibers A to D.

  The position-angle conversion unit 20COM includes input ports having different positions for each core of the fiber COM, and converts an optical signal input from a single mode fiber corresponding to each core into an angle (direction) corresponding to the position of the input port. ) To output to the LCOS side.

  The “position” is a one-dimensional position in the vertical direction in FIG. In the example of FIG. 10, four input ports corresponding to the number of cores (4) of the fiber COM are arranged. For example, if numbers such as input port 1, input port 2, input port 3, and input port 4 are numbered from the uppermost port downward, the optical signal input to input port 1 (the light indicated by a) Signal) is output at an angle corresponding to the position of the input port 1 at 20 COM, and the optical signal input to the input port 2 (optical signal indicated by b) is output at an angle corresponding to the position of the input port 2. The The same applies to the input port 3 and the input port 4.

  The position-angle conversion units 20A to 20D also have the same function as the position-angle conversion unit 20COM, except that the input / output is reversed.

  With regard to the above “angle”, for example, the optical signal indicated by “a” input to the input port 1 of 20 COM is output by the port selection lens 30 so as to be condensed on the portion indicated by “a” of the LCOS 40. The angle is set. The same applies to the optical signals indicated by b, c, and d.

  For example, regarding the position-angle conversion unit 20A, when an optical signal reflected from the portion a of the LCOS 40 is input to the position-angle conversion unit 20A via the port selection lens 30, it corresponds to the input angle. An optical signal is output from the output port to be input, and the optical signal is input to the corresponding core (core a of fiber A) via the single mode fiber connected to the output port. The same applies to the light reflected from the LCOS 40b, c, and d portions. The same applies to the position-angle conversion units 20B, C, and D.

  The port selection lens is a device that condenses the optical signal output from the position-angle conversion unit 20 on the LCOS 40.

  The LCOS (Liquid Crystal On Silicon: drive IC integrated liquid crystal element) 40 is an optical phase modulator having a very large number of fine pixels, and is a two-dimensional device. The reflected light from the LCOS 40 can be tilted by phase modulation. The LCOS 40 according to the present embodiment divides the region in the vertical direction (the direction in which ports in the position-angle conversion unit 20 are arranged) in FIG.

  FIG. 12 shows a division image of the LCOS region when viewed from the direction in which light is incident. In FIG. 12, for convenience, the x-axis and y-axis corresponding to the configuration shown in FIG. 11 are shown. That is, the y-axis direction is a direction in which the position changes depending on the wavelength, and the x-axis direction is a direction in which the position changes according to the port in the position-angle conversion unit 20.

  In the first embodiment, each area of the LCOS 40 corresponds to each core. Each core is a single mode, and the number of modes of each fiber is the number of cores of each fiber. For example, in the example of FIG. 10, if the cores in each fiber are core 1, core 2, core 3, and core 4, and the modes corresponding to the cores are mode 1, mode 2, mode 3, and mode 4, respectively, region a in LCOS 40 Corresponds to the core 1 and corresponds to the mode 1, and the region b corresponds to the core 2 and corresponds to the mode 2. The same applies to the areas c and d.

  As described above, the optical signal a input to the input port 1 in the position-angle conversion unit 20COM and output from the position-angle conversion unit 20COM is condensed on the region a of the LCOS 40 via the port selection lens 30. . For example, when the route is selected so that the optical signal a is connected to the fiber B, the optical signal a reflected from the region a of the LCOS 40 is input to the position-angle conversion unit 20B. In addition, the reflection angle in the region a of the LCOS 40 is set, and the optical signal a reflected from the region a of the LCOS 40 is input to the position-angle conversion unit 20B. Even when it is desired to connect to the fibers A, C, and D, the reflection angle in the region a may be set similarly. The above operation is the same for the regions b, c, and d.

  FIG. 13 is a diagram illustrating only a path related to the optical signal a in FIG. 10 in order to more easily understand the operation of the WSS of the first embodiment. As shown in FIG. 13, the optical signal a input to the input port 1 (uppermost port) of the position-angle conversion unit 20COM is condensed on the area a of the LCOS 40, and according to the route selection setting. , Connected to the core corresponding to the mode of the optical signal a in any one of the fibers A to D.

  14 and 15 are diagrams illustrating an example of the position-angle conversion unit 20. FIG. 14 shows an example in which the position-angle conversion unit 20 is realized by an optical waveguide (PCL) as described above.

  The position-angle conversion unit 20 can be realized by a device other than the optical waveguide, and an example thereof is shown in FIG. As shown in FIG. 15, the position-angle conversion unit 20 can be realized by a spatial optical system including an optical fiber and a convex lens.

(Example 2)
FIG. 16 is a configuration diagram of the WSS of Example 2 configuring the optical node device 100 according to the present embodiment. In the following, the WSS on the input side will be described, but the WSS on the output side can also be realized with the same configuration. The WSS on the output side corresponds to a reverse operation of the optical signal connection operation described below. As in the first embodiment, FIG. 16 shows only the switch surface in the WSS. The wavelength plane can be the same as the configuration of the wavelength plane in FIG. The basic configuration of the WSS in the second embodiment is the same as the configuration of the WSS in the first embodiment.

  The WSS of the second embodiment illustrated in FIG. 16 is a WSS used for a fiber having a plurality of cores in which each core propagates a plurality of modes. This fiber may be CC-MCF, FM-MCF, or GCC-MCF. In the following, the total number of modes that each fiber propagates is m, and the number of cores of each fiber is n. In the example illustrated in FIG. 16, the number of cores n of each fiber is n = 4, the total number m = 12 of modes that each fiber propagates, and the number of modes that one core propagates is m / n = 3. The first embodiment can be considered as a case of n = 4 and m = 4 (one mode per core) in the second embodiment.

  Similarly to the first embodiment, the fiber connected to the input side of the WSS is shown as a fiber COM, and the four fibers connected to the output side of the WSS are fiber A, fiber B, fiber C, and fiber D. It is shown.

  As shown in FIG. 16, the WSS includes a connection unit 55, a position-angle conversion unit 25, a port selection lens 30, and an LCOS 40.

  The connection unit 55 is a device that is provided for each core and connects each core of each fiber to single mode fibers corresponding to the number of modes of the core. Further, the connection unit 55 spatially samples an optical signal in which a plurality of modes output from the core are mixed, distributes the optical signal to the single mode optical signal corresponding to the number of modes, and inputs the optical signal to the single mode fiber corresponding to the mode. . In the reverse direction, the reverse process is performed.

  In the example of FIG. 16, the connection unit 55 connects each core of each fiber to three single mode fibers. Each single mode fiber of each core is connected to each port of the position-angle converter 25. Basically, as in the case of the first embodiment, each single mode fiber of each core is connected to a portion in the position-angle conversion unit 25 corresponding to the fiber to which the core belongs. However, in the present embodiment, the part is further divided into parts corresponding to the respective modes.

  For example, the connecting portion 55 corresponding to the second core from the top of the fiber COM (denoted as core b) in FIG. 16 is referred to as a connecting portion 55b (in FIG. 16, b is described in the corresponding connecting portion 55). If the first mode is expressed as mode 1b, the second mode is expressed as mode 2b, and the third mode is expressed as mode 3b (shown as 1, 2, and 3 in FIG. 16). The single mode fiber corresponding to the mode 1b connected to the connecting part 55b is the second part (the part indicated as COM1) corresponding to the first mode of the fiber COM in the position-angle converting part 25. Port (port corresponding to the core b).

  Similarly, for example, a single mode fiber corresponding to the mode 3c connected to the connection unit 55c is represented by a portion (COM3) corresponding to the third mode of the fiber COM in the position-angle conversion unit 25. To the third port (port corresponding to the core c).

  The same applies to other fibers / ports / modes. Further, the fibers A to D have the same connection configuration. For example, the second port from the top of the position indicated by A3 (corresponding to the third mode of each core of the fiber A) of the position-angle conversion unit 25 is connected to the second connection unit 55 from the top of the fiber A. Is done.

  The position-angle conversion unit 25 is a device integrated by an optical waveguide (PLC) as in the first embodiment. More specifically, as described above, the position-angle conversion unit 25 has a portion corresponding to each mode of each fiber.

  In FIG. 16, the characters COM and A to D are written in the positions in the position-angle conversion unit 25 corresponding to the fibers COM and A to D, respectively, and the corresponding mode numbers (numbers in each core). The number indicating whether the mode is For example, as already described, A3 of the position-angle conversion unit 25 corresponds to the third mode of each core of the fiber A.

  Further, for example, the COM 2 of the position-angle conversion unit 25 is connected to the single mode fiber of the second mode of each core of the fiber COM, and has an input port having a different position for each core, and a single unit corresponding to each core. The optical signal input from the one-mode fiber is output at an angle (direction) corresponding to the position of the input port. As in the first embodiment, the “position” is a one-dimensional position in the vertical direction in FIG. In the example of FIG. 16, four input ports corresponding to the number of cores (4) of the fiber COM are arranged.

  Regarding the above “angle”, for example, when an optical signal input to the input port 2 of the COM 2 (second mode output from the connection portion 55 b (core b) of the fiber COM) is output from the COM 2, the port The angle to be output is set so that the light is condensed by the selection lens 30 onto the portion indicated by b of the LCOS 40 (corresponding to the core b). The same applies to other fibers / cores / modes.

  For example, regarding the position-angle converter 25A2, when an optical signal reflected from the portion b of the LCOS 40 is input to the position-angle converter 20A2 via the port selection lens 30, it corresponds to the input angle. An optical signal is output from the output port (second port from the top), and the optical signal is input to the corresponding core (core b of fiber A) via the single mode fiber connected to the output port. . The same applies to the light reflected from the portions a, c, and d of the LCOS 40. The same applies to the position-angle conversion units 20B, C, and D.

  The port selection lens 30 is a device that condenses the optical signal output from the position-angle conversion unit 20 on the LCOS 40.

  Similar to the first embodiment, the LCOS 40 divides the region in the vertical direction (the direction in which the ports in the position-angle conversion unit 20 are arranged) in FIG. The division image of the LCOS region when viewed from the direction in which light is incident is as shown in FIG.

  In the second embodiment, each region corresponds to each core. However, each core has a plurality of modes, and each region receives the optical signal of the corresponding core's multiple modes, and the position-angle conversion unit corresponding to the mode in the fiber in which the optical signal of each mode is selected by route selection Reflected to 25 sites (via the port selection lens 30).

  For example, in the region b of the LCOS 40, when receiving the optical signal of the third mode (mode 3b) of the core b and connecting it to the fiber A, the optical signal reflected from the region b is converted into a position-angle conversion unit. 20 is input to A3, is output from the second port from the top, which is a port corresponding to the angle of the input, and is input to the core b of the fiber A.

  With the configuration shown in FIG. 16, the shuffle described with reference to FIG. 6 is realized, and the reflection angle of the LCOS 40 can be reduced. Further, by adjusting the angle at the time of reflection for each core, it is possible to adjust the coupling rate and adjust the power.

  FIG. 17 shows only the path of the optical signal related to the optical signal output from the core b (core connected to the connecting portion 55b) of the fiber com in FIG. 16 in order to more easily show the operation of the WSS of the second embodiment. FIG. As shown in FIG. 17, for example, the optical signal of mode 2b input to the input port 2 (second port from the top) of COM1 of the position-angle conversion unit 25 is condensed on the region b of the LCOS 40, Depending on the path selection setting, the fiber is connected to the core b (the core connected to the second connecting portion 55 from the top in each fiber) in any of the fibers A to D.

  FIG. 18 is a diagram for explaining the configuration of the second embodiment from the viewpoint of the number of cores, the number of modes, and the like. As shown in FIG. 18, the number of cores of each fiber is n, and the total number of modes that each fiber propagates is m. In this case, one connection unit 55 outputs (inputs) m / n modes. When the total number of fibers is N, the number of connection portions 55 is the total number of cores, which is nN. Further, each part (A3, B3,..., Etc.) of the position-angle conversion unit 25 is connected to each connection part 55 of the fiber A by n single-mode fibers. Further, the total number of parts of the position-angle conversion unit 25 is mN. In the position-angle conversion unit 25, N parts are provided for each mode. The total number of modes is m / nN, and the number of LCOS 40 regions is the number of cores n.

(Summary of embodiment)
As described above, according to the present embodiment, the wavelength selective switch in the optical node device constituting the WSDL optical network,
A position angle conversion unit, a port selection lens, and a switch element;
The position angle conversion unit includes a conversion part having input / output ports for the number of cores of the SDM fiber for each SDM fiber connected to the wavelength selective switch,
The conversion portion includes input / output ports at positions corresponding to the cores of the SDM fiber, and optical signals input to the input / output ports at an angle corresponding to the positions of the input / output ports. Means to output to the side,
The surface of the switch element that reflects the optical signal has a divided region divided for each core of the SDM fiber,
The optical signal input to the input / output port having the conversion site corresponding to the input SDM fiber is condensed on the divided region corresponding to the core corresponding to the position of the input / output port and reflected from the divided region. The optical signal is provided with a wavelength selective switch configured to reach a conversion site corresponding to the SDM fiber from which the optical signal is output.

Further, according to the present embodiment, the wavelength selective switch in the optical node device constituting the WSDL optical network,
A position angle conversion unit, a port selection lens, and a switch element;
The position angle conversion unit includes a conversion part having input / output ports for the number of cores of the fiber for each SDM fiber connected to the wavelength selective switch and for each mode propagating through the core of the SDM fiber,
The conversion portion includes input / output ports at positions corresponding to the cores of the SDM fiber, and optical signals input to the input / output ports at an angle corresponding to the positions of the input / output ports. Means to output to the side,
The surface of the switch element that reflects the optical signal has a divided region divided for each core of the SDM fiber,
An optical signal input to a certain input / output port of a conversion part corresponding to a certain mode of the input SDM fiber is condensed on a divided region corresponding to the core associated with the position of the input / output port, and the divided region The wavelength selective switch configured to reach the conversion part corresponding to the SDM fiber to which the optical signal is output and the mode is provided.

  Further, according to the present embodiment, there is provided an optical node device that includes the wavelength selective switch described above on each of the input side and the output side.

  The LCOS described in the embodiments is an example of the above switch element. Further, as described above, the means for the conversion site may be realized by an optical waveguide system or a spatial optical system.

(Effect of embodiment)
As described above, according to this embodiment, a WDSM optical node device can be constructed with a smaller number of WSSs. In addition, the coupling angle can be adjusted by adjusting the angle at the time of reflection in LCOS for each core, and the power can be adjusted for each core. Therefore, a fiber that combines a non-coupling type and a coupling type (eg, GCC) -Even when using MCF), an optical node device with one WSS per fiber can be realized.

  The present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the claims.

20, 25 Position-angle converter 30 Port selection lens 40 LCOS
50, 55 connection unit 100 optical node device

Claims (3)

A wavelength selective switch in an optical node device constituting a WSDL optical network,
A position angle conversion unit, a port selection lens, and a switch element;
The position angle conversion unit includes a conversion part having input / output ports for the number of cores of the SDM fiber for each SDM fiber connected to the wavelength selective switch,
The conversion portion includes input / output ports at positions corresponding to the cores of the SDM fiber, and optical signals input to the input / output ports at an angle corresponding to the positions of the input / output ports. Means to output to the side,
The surface of the switch element that reflects the optical signal has a divided region divided for each core of the SDM fiber,
The optical signal input to the input / output port having the conversion site corresponding to the input SDM fiber is condensed on the divided region corresponding to the core corresponding to the position of the input / output port and reflected from the divided region. The wavelength selective switch, wherein the optical signal is configured to reach a conversion site corresponding to the SDM fiber from which the optical signal is output. A wavelength selective switch in an optical node device constituting a WSDL optical network,
A position angle conversion unit, a port selection lens, and a switch element;
The position angle conversion unit includes a conversion portion having input / output ports corresponding to the number of cores of the SDM fiber for each SDM fiber connected to the wavelength selective switch and for each mode propagating through the core of the SDM fiber,
The conversion portion includes input / output ports at positions corresponding to the cores of the SDM fiber, and optical signals input to the input / output ports at an angle corresponding to the positions of the input / output ports. Means to output to the side,
The surface of the switch element that reflects the optical signal has a divided region divided for each core of the SDM fiber,
An optical signal input to a certain input / output port of a conversion part corresponding to a certain mode of the input SDM fiber is condensed on a divided region corresponding to the core associated with the position of the input / output port, and the divided region The wavelength selective switch, wherein the optical signal reflected from the light reaches the conversion part corresponding to the SDM fiber to which the optical signal is output and the mode.   An optical node device comprising the wavelength selective switch according to claim 1 on each of an input side and an output side.

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