Optical transmission apparatus

Abstract

Provided is an optical transmission apparatus having a configuration that facilitates application of a plurality of kinds of optical amplifiers having different amplifiable wavelength ranges, and enables execution of optical adjustment to individual signals even when output from the apparatus without performing path control in units of wavelength. The optical transmission apparatus according to the present disclosure comprises: a wavelength group demultiplexer that demultiplexes a wavelength multiplexed signal into optical signals of a wavelength group; a plurality of optical amplifiers that amplify the optical signals of the wavelength group; a wavelength-unit path processing block that executes path control in units of wavelength on the amplified optical signals of the wavelength group; an optical function device that performs optical adjustment on the amplified optical signals of the wavelength group individually; an optical switch function unit that selects an output route and an input route for optical signals of a wavelength group that is not propagated to the wavelength-unit path processing block, and outputs either an output from the wavelength-unit path processing block or the optical signals of the wavelength group that is not propagated to the wavelength-unit path processing block; and a wavelength group multiplexer that multiplexes the optical signals of the wavelength group output from the optical switch function unit.

Description

Optical Transmission Equipment

[0001] The present disclosure relates to an optical transmission device.

[0002] With the spread of the Internet, the demand for data communication networks is rapidly increasing. To meet this rapidly increasing demand, optical communication networks that can transmit large amounts of data with low power consumption are being widely constructed.

[0003] In addition to the function of directly connecting two points, such an optical communication network can also flexibly set routes by using optical transmission equipment that employs optical switches.

[0004] In recent years, an optical transmission device configuration called CDC-ROADM (Colorless, Directionless, Contention-less-Reconfigurable Optical Add Drop Multiplexer) has been widely used as an example of an optical transmission device that uses such an optical switch (see, for example, Non-Patent Document 1). Optical transmission devices in the form of CDC-ROADM are a method for performing efficient data communication in multi-directional networks such as multi-ring and mesh networks, and are characterized by their effectiveness in efficient management of communication resources.

[0005] Fig. 1 is a diagram showing a conceptual configuration of an optical transmission device 100 having the form of a conventional CDC-ROADM. As shown in Fig. 1, the optical transmission device 100 includes a wavelength selective switch (hereinafter referred to as WSS) 110 with one input and L outputs (where L is an integer greater than or equal to 2), an L-input, one-output WSS 120, an M-input, N-output (where M and N are integers greater than or equal to 2) receiver transponder aggregator (hereinafter referred to as TPA) 130, and an N-input, M-output transmitter TPA 140. Fig. 1 depicts a configuration in which M WSSs 110, 110-1 to 110-M, and M WSSs 120, 120-1 to 120-M, are arranged.

[0006] Of the output terminals of the L number of WSSs 110-1 to 110-M, the output terminal of M-1 is connected to the input terminal of M-1 WSSs 120 having a branch number different from its own branch number. For example, the output terminal of M-1 of WSS 110-1 is connected to the input terminal of WSSs 120 (WSSs 120-2 to 120-M) other than WSS 120-1. In other words, the connection relationship between the output terminal of WSS 110 and the input terminal of WSS 120 is configured such that the wiring between WSSs 110 and WSS 120 with the same branch number, which forms the return path, is deleted from a fully meshed wiring state.

[0007] Of the output terminals of the L number of WSSs 110-1 to 110-M, one output terminal is connected to the input terminal of the receiver TPA 130. Also, of the input terminals of the L number of WSSs 1210 to 120-M, one input terminal is connected to the output terminal of the transmitter TPA 140.

[0008] The 1-input, L-output WSSs 110-1 to 110-M have an optical switching function that allows users to select an output terminal for each wavelength of the input wavelength-multiplexed signal and output the wavelength-multiplexed signal. Furthermore, the L-input, 1-output WSSs 1210 to 120-M have a function to multiplex the input optical signals to form the output wavelength-multiplexed signal. The receiver TPA 130, for example, is a multicast switch configured by fully meshing M 1-input, N-output optical splitters 131 and N M-input, 1-output optical switches 132, and can output an optical signal input to any of the input terminals from any output terminal. The transmitter TPA 140, for example, is a multicast switch configured by fully meshing N 1-input, M-output optical switches 141 and M N-input, 1-output optical couplers 142, and can wavelength-multiplex and output an optical signal input from an input terminal as needed from any output terminal.

[0009] In the optical transmission device 100 configured in this manner, the optical signal input from the input terminal of the N-input / M-output transmitter TPA 140 may be of any wavelength and can be output from any of the WSSs 120-1 to 120-M. Optical signals of the same wavelength can be input to different input terminals of the transmitter TPA 140 under the condition that they are not output from the same WSS 120-1 to 120-M. Furthermore, the optical signal output from the output terminal of the M-input / N-output receiver TPA 130 can be an optical signal input from any of the WSSs 110-1 to 110-M. In other words, the optical transmission device 100 has functions known as colorless (capable of outputting any wavelength), directionless (capable of outputting to any route), and contention-less (no wavelength and route collisions).

[0010] As another example of an optical transmission device that uses an optical switch, in order to simplify the device configuration of the optical transmission device, a configuration is known in which the path switching unit is not only per signal wavelength, but also a combination of path switching per wavelength group consisting of multiple signal wavelengths (see, for example, non-patent document 2).

[0011] 2 is a diagram showing a conceptual configuration of a conventional optical transmission device 200. As described above, in order to simplify the device configuration, the optical transmission device 200 has a configuration in which path switching is performed not only in units of signal wavelengths but also in units of wavelength groups each consisting of a plurality of signal wavelengths. As shown in FIG. 2, the optical transmission device 200 includes P 1-input, Q-output wavelength group demultiplexers 210-1 to P (where P and Q are integers of 2 or greater), P Q-input, 1-output wavelength group multiplexers 220-1 to P, Q (P+R)-input, (P+R)-output optical switches 230-1 to Q (where Q is an integer of 2 or greater) provided for each wavelength group, R 1-input, S-output wavelength demultiplexers 240-q-1 to 240-q-R provided for the optical signals of the qth wavelength group (where q is an integer of 1 to Q) output from the optical switches 230-1 to Q, R S-input, 1-output wavelength multiplexers 250-q-1 to 250-q-R provided for the qth wavelength group, and Q×S 2R-input, 2R-output optical switches 260-1 to Q×S provided for each wavelength. 2 shows, as an example, a configuration in which P = 2, Q = 5, S = 8, R = 2, and q = 1. Also, in Fig. 2, the number of wavelengths of optical signals per fiber propagating through each transmission path (which may be an optical fiber) is depicted in a balloon block.

[0012] An optical signal multiplexed with Q×S (5×8=40 in FIG. 2 ) different wavelengths is input from the outside to one of wavelength group demultiplexers 210-1 to 210-P (wavelength group demultiplexers 210-1 to 210-2 in FIG. 2 ) as an input optical signal to optical transmission device 200. Each of wavelength group demultiplexers 210-1 to 210-2 demultiplexes the optical signal multiplexed with Q×S=40 different wavelengths into optical signals of Q=5 different wavelength groups into which S=8 different wavelengths are multiplexed, and outputs the demultiplexed optical signals of Q=5 different wavelength groups from different ports. That is, the input signal light input to optical transmission device 200 is input to one of wavelength group demultiplexers 210-1 to 210-2 and demultiplexed into optical signals multiplexed with S=8 different wavelengths. Each of the demultiplexed optical signals of the five different wavelength groups is input to optical switches 230-1 to 230-Q (optical switches 230-1 to 230-5 in FIG. 2 ) via a transmission path.

[0013] Optical switches 230-1 to 230-5 are optical switches provided one for each of the optical signals of the five wavelength groups. Each of optical switches 230-1 to 230-5 has (P+R) (2+2=4 in FIG. 2 ) input ports, of which P=2 input ports are connected to output ports of wavelength group demultiplexers 210-1 to 210-2 that output optical signals of the corresponding wavelength groups. For example, the first output port of wavelength group demultiplexer 210-1 is connected to the input port of optical switch 230-1, and the fifth output port of wavelength group demultiplexer 210-1 is connected to 230-5. Similarly, the first output port of wavelength group demultiplexer 210-2 is connected to the input port of optical switch 230-1, and the fifth output port of wavelength group demultiplexer 210-2 is connected to 230-5. Then, in each of optical switches 230-1 to 230-5, the optical signals of the input wavelength groups are output from any output port. The connection relationships of the remaining R input ports of the optical switches 230-1 to 230-Q (that is, the input ports not connected to 210-1 to 210-Q) will be described separately later.

[0014] The wavelength group multiplexers 220-1 to 220-P (wavelength group multiplexers 220-1 to 220-2 in the figure) are connected to the output ports of the optical switches 230-1 to 230-5, and have the function of multiplexing the optical signals of the wavelength groups output from the optical switches 230-1 to 230-5 and outputting the multiplexed signals to the outside via a transmission path. Of the (P+R)= output ports of the optical switches 230-1 to 230-5, P=2 output ports are connected to the input ports of the wavelength group multiplexers 220-1 to 220-2 that input signals of the corresponding wavelength groups. For example, the first output port of the optical switch 230-1 is connected to the input port of the wavelength group multiplexer 220-1, and the second output port is connected to the input port of the wavelength group multiplexer 220-2. Similarly, the first output port of the optical switch 230-5 is connected to the input port of the wavelength group multiplexer 220-1, and the second output port is connected to the input port of the wavelength group multiplexer 220-2. The optical signals of the wavelength groups output from the two output ports of the optical switches 230-1 to 230-5 are multiplexed by the wavelength group multiplexers 220-1 to 220-2, respectively, and output to the outside.

[0015] Each of the optical switches 230-1 to 230-5 further includes R (2 in FIG. 2 ) output ports that are not connected to the wavelength group multiplexers 220-1 to 220-2. Now, assuming q=1, and focusing on the optical switch 230-1 that inputs and outputs optical signals of the first wavelength group, the R=2 output ports of the optical switch 230-1 are input to wavelength demultiplexers 240-q-1 to q-R (wavelength demultiplexers 240-1-1 to 1-2 in FIG. 2 ), each with 1 input and S outputs (1 input, 8 outputs in FIG. 2 ). Each of the wavelength demultiplexers 240-1-1 to 1-2 has the function of outputting S=8 wavelengths that make up the q=1 wavelength group from a different port. Similarly, when q=2, the R=2 output ports of the switch 230-2 are input to wavelength demultiplexers 240-2-1 to 2-2 (not shown), each with 1 input and 8 outputs.

[0016] Optical switches 260-1 to 260-40 are 2R input / 2R output (4 input / 4 output in FIG. 2 ) optical switches, each provided for a wavelength demultiplexed by wavelength demultiplexers 240-q-1 to q-R, with R=2 input ports connected to output ports of wavelength demultiplexers 240-q-1 to 240-q-R that output optical signals of the corresponding wavelengths. For example, the output ports of wavelength demultiplexers 240-1-1 to 240-1-2 are input to optical switches 260-1 to 260-8, as shown in FIG. 2 . Similarly, wavelength demultiplexers 240-2-1 to 2-2 (not shown) are connected to optical switches 260-9 to 260-16.

[0017] Each of the optical switches 230-1 to 230-5 further includes R (2 in FIG. 2) input ports that are not connected to the wavelength group demultiplexers 210-1 to 210-2. Now, assuming q=1, and focusing on the optical switch 230-1 that inputs and outputs optical signals of the first wavelength group, the R input ports of the optical switch 230-1 are connected to the output ports of wavelength multiplexers 250-q-1 to 250-q-R (250-1-1 to 250-1-2 in FIG. 2), each with S inputs and 1 output (8 inputs and 1 output in FIG. 2). The wavelength multiplexers 250-1-1 to 250-1-2 have the function of multiplexing optical signals having different wavelengths and outputting optical signals of wavelength groups with S=8 outputs. The optical signals having different wavelengths are optical signals propagated from the R=8 output ports of the optical switches 260-1 to 260-8. That is, the output ports of optical switches 260-1 to 260-8 are connected to the input ports of wavelength multiplexers 250-1-1 to 250-1-2. Similarly, the output ports of optical switches 260-9 to 260-16 are connected to the input ports of wavelength multiplexers 250-2-1 to 250-2-2 (not shown).

[0018] Each of the optical switches 260-1 to 260-40 further includes R=2 output ports that are not connected to the wavelength multiplexers 250-q-1 to 250-q-R. These output ports are connected to a group of optical signal receivers. Furthermore, the optical switches 260-1 to 260-40 further include R=2 input ports that are not connected to the wavelength demultiplexers 240-q-1 to 240-q-R. These input ports are connected to a group of optical signal transmitters. Note that FIG. 2 depicts a configuration in which the optical switch 260-1 is connected to the group of receivers and the group of transmitters by two optical fibers each (in other words, the group of receivers is composed of two receivers, and the group of transmitters is composed of two transmitters), but this is for illustrative purposes only, and any number of receivers and transmitters may be installed depending on the design.

[0019] The optical transmission device 200 having such a configuration is configured so that, after an input optical signal (wavelength-multiplexed signal) input from a transmission path is demultiplexed into wavelength groups, it can be selected, depending on the routing settings of the optical switches 230-1 to 230-Q, whether the input optical signal is selected and input to wavelength group multiplexers 220-1 to 220-P and multiplexed before being output to the outside, or whether the input is selected and input to wavelength demultiplexers 240-q-1 to 240-q-R and demultiplexed into wavelength groups. Furthermore, the optical transmission device 200 is configured so that, depending on the routing settings of the optical switches 260-1 to 260-Q×S, it can be selected whether the optical signals demultiplexed by wavelength by wavelength demultiplexers 240-q-1 to 240-q-R are selected and received by a selected optical signal receiver, or whether the optical signals are selected and input to wavelength multiplexers 250-q-1 to 250-q-R and a wavelength group signal is generated.

[0020] Furthermore, the optical transmission device 200 is configured so that an optical signal output from a transmitter is selectively input to wavelength multiplexers 250-q-1 to 250-q-R by route setting of optical switches 260-1 to 260-Q×S, and a wavelength-group signal is generated. Similarly, the optical transmission device 200 is also configured so that a wavelength-group signal generated by wavelength multiplexers 250-q-1 to 250-q-R is selectively input to wavelength-group multiplexers 220-1 to 220-P by route setting of optical switches 230-1 to 230-Q, and is multiplexed and then output to the outside.

[0021] By using such an optical transmission device 200, a user can select whether to route an input optical signal (wavelength multiplexed signal) in units of wavelength or in units of wavelength group. Compared to devices that perform route control entirely in units of wavelength, this optical transmission device 200 can reduce the degree of freedom in route control by providing a processing hierarchy for wavelength groups, which has a coarse routing control granularity, and can also simplify the device configuration.

[0022] Typically, the amount of data that can be transmitted through a single optical fiber is limited to the product of the number of signals that can be wavelength-multiplexed on the optical fiber and the signal speed of the optical transmitter / receiver. However, recent technological trends in optical transmission devices have made it difficult to improve frequency utilization efficiency. Therefore, to double the signal speed, the occupied wavelength band also doubles, and the number of signals that can be wavelength-multiplexed is halved, resulting in no increase in the amount of data that can be transmitted through a single optical fiber. Under these circumstances, one way to increase the amount of data that can be transmitted through a single optical fiber is to widen the wavelength band used for transmission.

[0023] Generally, the wavelength band used for transmission is determined by optical devices that have limitations on the wavelengths that can be used, and in many cases, the wavelength range that can be amplified by an optical amplifier coincides with the wavelength band used for transmission. In this case, widening the wavelength band used for transmission means using multiple types of optical amplifiers that can be used in different wavelength ranges for optical transmission.

[0024] However, the conventional optical transmission device 100 is not designed to accommodate multiple types of optical amplifiers with different amplifiable wavelength ranges, and is therefore not easily adaptable to multiple types of optical amplifiers. In contrast, the optical transmission device 200 includes wavelength group demultiplexers 210-1 to 210-P and wavelength group multiplexers 220-1 to 220-P, and is therefore easily adaptable to multiple types of optical amplifiers by matching the amplifiable wavelength ranges with the wavelength groups.

[0025] On the other hand, the conventional optical transmission device 100 has a function for controlling the routing of individual wavelength-multiplexed signals within the device, and in conjunction with this function, can perform optical adjustments such as adjusting the optical signal levels of individual wavelength-multiplexed signals. In contrast, the conventional optical transmission device 200 has a function for controlling routing on a wavelength-group basis within the device, and can output signals from the device without routing control on a wavelength-by-wavelength basis, but on the other hand, it is difficult to perform optical adjustments on individual signals when routing control on a wavelength-by-wavelength basis is not performed.

[0026] T. Watanabe, K. Suzuki and T. Takahashi: "Silica-based PLC transponder aggregators for colorless, directionless, and contentionless ROADM," Optical Fiber Communication Conference (OFC), Paper OTh3D.1 (2012). O. Moriwaki et al., "Terabit-scale hierarchical compact optical cross-connect system employing PLC devices and optical backplane," 2010 Conference on Optical Fiber Communication (OFC / NFOEC), collocated National Fiber Optic Engineers Conference, Paper PDPC9 (2010).

[0027] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide an optical transmission device that is configured to easily apply multiple types of optical amplifiers with different amplifiable wavelength ranges, and that is configured to allow optical adjustment of individual signals even when output from the device without route control on a wavelength-by-wavelength basis.

[0028] In order to achieve such an object, the present disclosure provides an optical transmission device having one or a plurality of wavelength multiplexed signal input / output ports, the optical transmission device comprising: a wavelength group demultiplexer that demultiplexes an input wavelength multiplexed signal into optical signals of two or more wavelength groups; and a plurality of optical amplifiers that amplify each of the optical signals of the wavelength group output from the wavelength group demultiplexer, each of which has a different amplifiable wavelength range; a method for controlling the path of the optical signals of the wavelength group amplified by the optical amplifier for each wavelength of the optical signal to generate an optical signal of the wavelength group to be output; a method for inputting an optical signal received from the input optical signals of the wavelength group to an optical receiver; and a method for outputting an optical signal transmitted from an optical transmitter. an optical function device that performs optical adjustments individually according to wavelength to the optical signals of the wavelength group amplified by the optical amplifier; an optical switch function unit that selects an output route and an input route for the optical signals of the wavelength group that are not propagated to the wavelength unit route processing block among the optical signals of the wavelength group amplified by the optical amplifier, and outputs either the output of the wavelength unit route processing block or the output of the optical signal of the wavelength group that is not propagated to the wavelength unit route processing block; and a wavelength group multiplexer that multiplexes and outputs the optical signals of the wavelength group output from the optical switch function unit.

[0029] 3A and 3B are diagrams illustrating a conceptual configuration of an optical transmission device 100 having the form of a CDC-ROADM according to the prior art; a diagram illustrating a conceptual configuration of an optical transmission device 200 according to the prior art; a diagram conceptually illustrating a configuration of an optical transmission device 300 according to the present disclosure; a diagram conceptually illustrating a configuration of another form of the optical transmission device 300 according to the present disclosure; and a diagram illustrating another form of the circuit configuration in the range from an optical amplifier 304 to an optical switch 312, in which (a) illustrates a form in which an optical functional device 309 is arranged at each output port of an optical switch 310, (b) illustrates a form in which an optical functional device is arranged between the optical amplifier 304 and the optical switch 310, and (c) illustrates a form in which the optical switches 310 and 311 in the circuit configuration shown in FIG. 3 are replaced with a multi-input multi-output optical switch 401.

[0030] Various embodiments of the present disclosure will be described in detail below with reference to the drawings. The same or similar reference numerals indicate the same or similar elements, and redundant description may be omitted. Materials and numerical values ​​are for illustrative purposes only and are not intended to limit the technical scope of the present disclosure. The following description is an example, and some configurations may be omitted or modified, or additional configurations may be added, as long as they do not deviate from the gist of one embodiment of the present disclosure.

[0031] 3 is a conceptual diagram illustrating the configuration of an optical transmission device 300 according to the present disclosure. As illustrated in FIG. 3, the optical transmission device 300 includes a wavelength group demultiplexer 303 that demultiplexes an externally input wavelength-multiplexed signal into optical signals of two or more wavelength groups, a plurality of optical amplifiers 304 that amplify each of the optical signals of the wavelength groups output from the wavelength group demultiplexer 303, a plurality of one-input, two-output optical switches 307 connected to each output port of the optical amplifiers 304, a wavelength cross-connect function unit 308 connected to one output port of each of the optical switches 307, and a wavelength cross-connect function unit 309 connected to the other output port of each of the optical switches 307. The optical transmission device 300 includes a plurality of optical functional devices 309, a plurality of one-input multiple-output optical switches 310 connected to the output ports of the optical functional devices 309, a multiple-input single-output optical switch 311 connected to the output ports of the optical switch 310, a plurality of two-input single-output optical switches 312 connected to the output ports of the optical switch 311 and the output ports of the wavelength cross-connect functional unit 308, and a wavelength group multiplexer 313 connected to the output ports of the optical switch 312 and multiplexing two or more input wavelength groups. Note that Fig. 3 illustrates a case where the optical transmission device 300 has one input port to which an externally input wavelength multiplexed signal is input and one output port to which the wavelength multiplexed signal is output to the outside. However, this is intended for illustrative purposes only, and any number of input ports and output ports may be arranged in the transmission device 300 depending on the design.

[0032] When a wavelength-multiplexed signal is input from outside the optical transmission device 300, the externally input wavelength-multiplexed signal is demultiplexed into two or more wavelength groups by the wavelength group demultiplexer 303. Each of the optical signals of the demultiplexed wavelength groups is input to an optical amplifier 304 configured to be able to amplify the optical signal of the corresponding wavelength group. Examples of combinations of wavelength groups and optical amplifiers 304 include a case where the wavelength group is the C band and the optical amplifier 304 is a C-band EDFA, a case where the wavelength group is the L band and the optical amplifier 304 is an L-band EDFA, or a case where the wavelength group is the S band and the optical amplifier 304 is a thulium-doped fiber amplifier TDFA. As another example, the optical amplifier 304 may be a lumped Raman amplifier, i.e., configured to multiplex a pump light source with a wavelength shorter than the wavelength to be amplified and transfer the power of the pump light to the signal light during propagation through the fiber. 3, three optical amplifiers 304 are illustrated, but this is for illustrative purposes only, and any number of optical amplifiers 304 may be arranged depending on the design. Furthermore, the wavelength ranges that the optical amplifiers 304 can amplify may all be different from each other.

[0033] The optical signals of the wavelength group amplified by each of the optical amplifiers 304 can be input to each of the corresponding optical switches 307. As described above, the optical switch 307 is a one-input, two-output optical switch, and is configured to enable the input optical signals of the wavelength group to be selectively input to the wavelength cross-connect functional unit 308 or the optical functional device 309 according to a user's selection. In other words, the optical switch 307 is configured so that the user can select (control) whether the input optical signals of the wavelength group amplified by each of the optical amplifiers 304 are propagated to the wavelength cross-connect functional unit 308 or the optical functional device 309. However, as described below, the optical switch 307 does not necessarily need to be provided, and for example, one of the output ports of the optical switch 310 described below may be connected to the input port of the wavelength cross-connect functional unit 308. Also, in FIG. 3, each of the optical switches 307 is depicted as having one input and two outputs, but this is intended for illustrative purposes only, and the number of input and output ports of the optical switch 307 may be set arbitrarily depending on the design.

[0034] The wavelength cross-connect function unit 308 may be configured to realize cross-connect functionality on a wavelength-by-wavelength basis. For example, as shown in FIG. 3, the wavelength cross-connect function unit 308 may have a configuration similar to that of the optical transmission device 100 according to the prior art described above. As shown in FIG. 3, in the wavelength cross-connect function unit 308, optical signals of wavelength groups can be input from the optical switch 307 to an input WSS at the user's selection. Similar to the WSSs 110-1 to 110-M in FIG. 1 described above, the WSS is configured to select an output terminal (perform routing control) for each wavelength of the input optical signals of the wavelength groups at the user's selection, and output the optical signals from the output WSS to the optical switch 312. Note that while some WSSs in FIG. 3 are depicted in a two-band configuration, this is for illustrative purposes only. Furthermore, the optical signals of the wavelength groups input to the input WSS can be received by any optical receiver Rx via a multicast switch (hereinafter referred to as MCS) at the user's selection. In addition, the wavelength cross-connect function unit 308 is configured so that an optical signal of a wavelength group input from an arbitrary optical transmitter Tx is input to the output-side WSS via an MCS, multiplexed with an optical signal of the wavelength group input from the input-side WSS, and then output to the optical switch 312. Note that, although Fig. 3 depicts a case where an MCS compatible with all three bands is applied as a device that controls the multiplexing / demultiplexing function located between the WSS and the optical receiver Rx or optical transmitter Tx, this is intended as an example, and the device that controls the multiplexing / demultiplexing function may be any device that has the required functions, such as an arrayed waveguide grating, or an MCS or WSS that supports a single band.

[0035] The wavelength cross-connect functional unit 308 configured in this manner has the functions of controlling the routing of optical signals of the input wavelength group for each wavelength and generating optical signals of the output wavelength group, inputting optical signals received from the input optical signals of the wavelength group to an optical receiver, and multiplexing optical signals transmitted from the optical transmitter into optical signals of the appropriate wavelength group to be output. When each of the optical signals of the wavelength group amplified in the optical amplifier 304 described above is input to the wavelength cross-connect functional unit 308 according to user selection in the optical switch 307, the optical signals of the wavelength group are routed for each wavelength in this wavelength cross-connect functional unit 308 and then optically adjusted.

[0036] In the above description of the wavelength cross-connect function unit 308, the wavelength cross-connect function unit 308 is described as having a configuration similar to that of the optical transmission device 100 according to the prior art. However, this is intended as an example, and the wavelength cross-connect function unit 308 is not limited to the form of a CDC-ROADM. For example, the wavelength cross-connect function unit 308 may be configured to input and output wavelength signals using a wavelength multiplexer / demultiplexer such as an arrayed waveguide grating (AWG), to input and output wavelength signals colorlessly using a WSS, or to input and output wavelength signals colorlessly and directionlessly using a multiple-input / multiple-output WSS or MCS. In such cases, the wavelength cross-connect function unit 308 is referred to as a wavelength-based route processing block 308 because it not only provides cross-connect functionality on a wavelength-by-wavelength basis, but also realizes route control on a wavelength-by-wavelength basis.

[0037] On the other hand, the optical functional device 309 is a device for individually optically adjusting, according to wavelength, optical signals of a wavelength group for which a route that does not pass through the wavelength cross-connect functional unit 308 is selected in the optical switch 307. More specifically, the optical functional device 309 applies, either fixedly or adaptively, one or more of wavelength-dependent loss, polarization-dependent loss, or wavelength-dependent delay to each optical signal of the wavelength group. The optical functional device 309 may take the form of a passive one-input one-output device, such as a filter that equalizes the wavelength dependence of optical intensity. In this way, when each optical signal of the wavelength group amplified in the optical amplifier 304 is input to the optical functional device 309 according to a user's selection in the optical switch 307, each optical signal of the wavelength group is optically adjusted without route control.

[0038] The output port of the optical functional device 309 is input to a single-input, multiple-output optical switch 310 for selecting an output route. If the number of output routes is N, the number of output ports of the optical switch 310 should be equal to or greater than N. However, if the condition that there is no return to the input route is accepted, the number of route options is reduced by one, so the number of output ports of the optical switch 310 becomes the minimum value, N-1.

[0039] The output ports of the one-input multi-output optical switch 310 are all connected to input ports of different multi-input single-output optical switches 311. An optical switch 311 is provided for each output port of the optical switch 310, and is configured so that the user can select the input route.

[0040] As will be described later, the optical functional device 309 may be disposed between the optical switch 310 and the optical switch 311. In such a case, the optical functional device 309 needs to be disposed for each of the transmission paths connected to the output port of the optical switch 310. In addition, the optical functional device 309 may be disposed between the optical switch 311 and the wavelength group multiplexer 313.

[0041] Furthermore, the optical switches 310 and 311 may be replaced with an integrated multi-input multi-output optical switch.

[0042] The optical switch 312 is a two-input, one-output optical switch arranged for each of the optical switches 311, and its input port is connected to the output port of the optical switch 311 and the output port of the wavelength cross-connect function unit 308. In other words, the optical switch 312 is configured so that the user can select (control) and output either the optical signal that has passed through the wavelength cross-connect function unit 308 or the optical signal that has passed through the optical functional device 309, from among the optical signals of the wavelength group that have been input and amplified by each of the optical amplifiers 304.

[0043] Each output port of the optical switch 312 is connected to an input port of the wavelength group multiplexer 313. The wavelength group multiplexer 313 has a function of multiplexing and outputting optical signals of multiple wavelength groups that have been optically adjusted by the wavelength cross-connect function unit 308 or the optical functional device 309.

[0044] The optical transmission device 300 according to the present disclosure having such a configuration has the advantage that it is easy to apply multiple types of optical amplifiers with different amplifiable wavelength ranges, due to the arrangement of multiple optical amplifiers 304. Furthermore, the optical transmission device 300 according to the present disclosure can perform optical adjustment of individual signals using the optical functional device 309, even when the signals are output from the device via a path that directly connects the one-input, multiple-output optical switch 310 and the multiple-input, single-output optical switch 311 (in other words, without passing through the wavelength cross-connect function unit 308 that controls the path on a wavelength-by-wavelength basis).

[0045] 4, the optical transmission device 300 according to the present disclosure may further include a first optical multiplexing unit 301 on the input side of the wavelength group demultiplexer 303, and an optical signal source 302 that inputs an optical signal to the first optical multiplexing unit 301. In addition, the optical transmission device 300 according to the present disclosure may include a second optical multiplexing unit 305 on the output side of the wavelength group multiplexer 313, and a second optical signal source 306 that inputs an optical signal to the second optical multiplexing unit 305, as shown in FIG.

[0046] The first optical multiplexing means 301 has a common port that serves as the input side for an externally input wavelength-multiplexed signal and the output side for an optical signal with a shorter wavelength than the externally input wavelength-multiplexed signal, a long-wavelength port connected to the wavelength group demultiplexer 303, and a short-wavelength port connected to a light source (first optical signal source 302, described later) for an optical signal with a shorter wavelength than the externally input wavelength-multiplexed signal. The first optical multiplexing means 301, having such a configuration, corresponds to a device generally called a WDM coupler and functions to input an externally input wavelength-multiplexed signal from the common port, output it from the long-wavelength port, and propagate it to the wavelength group demultiplexer. Furthermore, the first optical multiplexing means 301 also functions to propagate an optical signal with a shorter wavelength than the externally input wavelength-multiplexed signal from the short-wavelength port to the common port, i.e., in the opposite direction to the other optical signal (the externally input wavelength-multiplexed signal). This function makes it possible to amplify the optical signal intensity of some or all of the other optical signals. Optical signals with wavelengths shorter than the externally input wavelength-multiplexed signal are output from the first optical signal source 302. The first optical signal source 302 may be a Raman pump light source that amplifies a certain wavelength range on the super wavelength side of the light source by propagating a high signal level through a transmission line. Note that the optical transmission device 300 may be configured such that the same function as the first optical multiplexing means 301 is realized inside the wavelength group demultiplexer 303.

[0047] The second optical multiplexing means 305 has a common port that serves as the output side for the wavelength-multiplexed signal multiplexed and output by the wavelength group multiplexer 313 and an optical signal with a wavelength shorter than that of the wavelength multiplexed signal input from an external device, a long-wavelength port connected to the wavelength group multiplexer 313, and a short-wavelength port connected to a light source (a second optical signal source 306 described later) of an optical signal with a wavelength shorter than that of the wavelength multiplexed signal. The second optical multiplexing means 305 having such a configuration corresponds to a device generally called a WDM coupler, and has the function of inputting the wavelength-multiplexed signal output from the wavelength group multiplexer 313 through the long-wavelength port, outputting it through the common port, and propagating it to the outside. Furthermore, the second optical multiplexing means 305 also has the function of propagating light with a wavelength shorter than that of the wavelength-multiplexed signal input from an external device from the short-wavelength port to the common port, i.e., propagating light with a wavelength shorter than that of the wavelength-multiplexed signal input from an external device in the same direction as other signal light (the optical signal multiplexed and output by the wavelength group multiplexer 313). This function makes it possible to amplify the optical signal intensity of some or all of the other signal light. An optical signal having a wavelength shorter than that of the wavelength multiplexed signal output from the wavelength group multiplexer 313 is output from a second optical signal source 306. The second optical signal source 306 may be a Raman pump light source that amplifies a certain wavelength range on the super wavelength side of the light source by propagating a high signal level through a transmission line. Note that the optical transmission device 300 may be configured such that the same function as the second optical multiplexing means 305 is realized inside the wavelength group multiplexer 313.

[0048] 3, the position where the optical functional device 309 is mounted is preferably the output side of the optical switch 307. This is because there is an additional advantage that the optical functional device 309 does not become a factor of loss for signals passing through the wavelength cross-connect function unit 308, and the number of devices to be mounted can be the same as the number of input routes. However, from the viewpoint of solving the above-mentioned problem to be solved by the optical transmission device according to the present disclosure, the position where the optical functional device 309 is mounted may be anywhere within the range from the output side of the optical amplifier 304 to the input side of the wavelength group multiplexer 313.

[0049] 5A and 5B are diagrams illustrating other forms of circuit configuration in the range from the optical amplifier 304 to the optical switch 312, where (a) shows a form in which the optical functional device 309 is arranged at each output port of the optical switch 310, (b) shows a form in which the optical functional device 309 is arranged between the optical amplifier 304 and the optical switch 310, and (c) shows a form in which the optical switch 310 and the optical switch 311 in the circuit configuration shown in FIG. 3 are replaced by a multi-input multi-output optical switch 401.

[0050] 5(a), the output port of the optical amplifier 304 is connected to the input port of the optical switch 310, one of the output ports of the optical switch 310 is connected to the input port of the wavelength cross-connect function unit 308, and the remaining output ports for each degree are connected to the optical functional device 309. In this configuration, the optical switch 307 is not required, but a large number of optical functional devices 309 are required.

[0051] The configuration shown in Fig. 5(b) is similar to that shown in Fig. 5(a), but differs in that the optical functional device 309 is disposed between the optical amplifier 304 and the optical switch 310. The configuration shown in Fig. 5(b) has the advantage of being able to reduce the number of components compared to the configuration shown in Fig. 5(a), but the optical signal input to the wavelength cross-connect functional unit 308 is an optical signal that has passed through the optical functional device 309 in advance, which may lead to a loss of transmission efficiency.

[0052] As described above, the configuration shown in FIG. 5C corresponds to the configuration in which the optical switches 310 and 311 in the circuit configuration shown in FIG. 3 are replaced with the multi-input multi-output optical switch 401.

[0053] In either of the configurations shown in Figure 5, as with the configuration shown in Figure 3, it is easy to apply multiple types of optical amplifiers with different amplifiable wavelength ranges, and the configuration makes it possible to perform optical adjustments for individual signals even when output from the device without route control on a wavelength-by-wavelength basis.

[0054] In another embodiment, for example, in the optical transmission device 300, if the optical functional device 309 is not disposed between the optical switch 307 and the optical switch 310, the optical switch 307 and the optical switch 310 may be replaced with an integrated one-input multi-output optical switch.

[0055] As yet another embodiment, for example, in the optical transmission device 300, when the optical functional device 309 is not disposed between the optical switches 311 and 312, the optical switches 311 and 312 may be replaced with an integrated multi-input, single-output optical switch. Furthermore, when the optical functional device 309 is not disposed between the optical switches 310 and 311, the optical switches 310 and 311 may be replaced with a single integrated multi-input, multi-output optical switch.

[0056] The number of input / output ports of each of the optical switches 310, 311, and 312 in the above description is intended to be an example, and may be set arbitrarily according to the design.

[0057] As described above, the optical transmission device according to the present disclosure is configured to easily apply multiple types of optical amplifiers with different amplifiable wavelength ranges, and to optically adjust individual signals even when output from the device without routing control on a wavelength-by-wavelength basis. This optical transmission device facilitates expanding the wavelength band used for transmission and easily increases the amount of data that can be transmitted over a single optical fiber. Therefore, it is expected to be put into practical use as an optical transmission device capable of transmitting much larger amounts of data than conventional technology.

[0058] 100 Optical transmission device 110, 110-1 to M, 120, 120-1 to M WSS 130 TPA for receiver 131 Output optical splitter 132 Optical switch 140 TPA for transmitter 141 Optical switch 142 Optical coupler 200 Optical transmission device 210-1 to P Wavelength group demultiplexer 220-1 to P Wavelength group multiplexer 230-1 to Q Optical switch 240-q-R Wavelength demultiplexer 250-q-R Wavelength multiplexer 260-Q×S Optical switch 300 Optical transmission device 301 First optical multiplexing means 302 Optical signal source 303 Wavelength group demultiplexer 304 Optical amplifier 305 Second optical multiplexing means 306 Second optical signal source 307 Optical switch 308 Wavelength cross-connect function unit 309 Optical functional device 310 Optical switch 311 Optical switch 312 Optical switch 313 Wavelength group multiplexer 401 Optical switch

Claims

1. An optical transmission device having one or more input / output ports for wavelength multiplexed signals, comprising: a wavelength group demultiplexer that demultiplexes the input wavelength multiplexed signal into optical signals of two or more wavelength groups; a plurality of optical amplifiers that amplify each of the optical signals of the wavelength group output from the wavelength group demultiplexer, each of which has a different amplifiable wavelength range; a wavelength unit route processing block that performs route control for each wavelength of the optical signal of the wavelength group amplified by the optical amplifier to generate an optical signal of the wavelength group to be output, inputs an optical signal received from the input optical signals of the wavelength group to an optical receiver, and multiplexes an optical signal to be transmitted from an optical transmitter into an optical signal of the appropriate wavelength group to be output; and an optical functional device that performs optical adjustments according to the wavelength of the optical signals of the wavelength group amplified by the optical amplifier. an optical switch function unit that selects an output route and an input route for optical signals of the wavelength group that are not propagated to the wavelength unit route processing block, among the optical signals of the wavelength group amplified by the optical amplifier, and outputs either the output of the wavelength unit route processing block or the output of the optical signals of the wavelength group that are not propagated to the wavelength unit route processing block; and a wavelength group multiplexer that multiplexes and outputs the optical signals of the wavelength group output from the optical switch function unit.

2. The optical transmission device according to claim 1, further comprising a first optical switch arranged on the output side of each of said optical amplifiers and directing the optical signals of said wavelength group output from each of said optical amplifiers to either said wavelength unit path processing block or said optical functional device.

3. The optical transmission device according to claim 1 or 2, wherein said optical switch function section includes one multiple-input, multiple-output optical switch.

4. The optical transmission device of claim 1 or 2, wherein the optical switch function unit comprises: a plurality of second optical switches to which each of the optical signals of the wavelength group amplified by the optical amplifier is input; a plurality of third optical switches arranged on the output side of the second optical switches; and a plurality of fourth optical switches connected to the output side of the wavelength unit path processing block and the output side of the third optical switches.

5. The optical transmission device described in claim 4, wherein an output port of the second optical switch is connected to an input port of the third optical switch and an input port of the wavelength unit path processing block, and the optical functional devices are each arranged on a transmission path connecting the output port of the second optical switch and the input port of the third optical switch.

6. The optical transmission equipment according to claim 4, wherein an output port of the second optical switch is connected to an input port of the third optical switch and an input port of the wavelength unit path processing block, and the optical functional devices are each arranged on a transmission path connecting the output port of the optical amplifier and the input port of the second optical switch.

7. The optical transmission device described in claim 4, wherein an output port of the second optical switch is connected to an input port of the third optical switch and an input port of the wavelength unit path processing block, and the optical functional devices are each arranged on a transmission path connecting the output port of the third optical switch and the input port of the wavelength group multiplexer.

8. The optical transmission device according to claim 1, further comprising a first optical signal source that generates an optical signal having a shorter wavelength than the wavelength multiplexed signal and inputs the shorter wavelength optical signal to the wavelength group demultiplexer, the wavelength group demultiplexer being configured to multiplex the shorter wavelength optical signal and the input wavelength multiplexed signal and to propagate the shorter wavelength optical signal in a direction opposite to that of the input wavelength multiplexed signal.

9. The optical transmission device according to claim 1, further comprising: a first optical signal source that generates an optical signal having a shorter wavelength than the wavelength multiplexed signal; and first optical multiplexing means that is further configured to multiplex the optical signal having the shorter wavelength with the wavelength multiplexed signal input from outside, and to propagate the optical signal having the shorter wavelength in a direction opposite to that of the wavelength multiplexed signal input from outside.

10. The optical transmission device according to claim 1, further comprising a second optical signal source that generates an optical signal having a shorter wavelength than the optical signal output from the wavelength group multiplexer and inputs the shorter wavelength optical signal to the wavelength group multiplexer, and the wavelength group multiplexer is configured to multiplex the shorter wavelength optical signal and the wavelength multiplexed signal output from the wavelength group multiplexer and propagate the shorter wavelength optical signal in the same direction as the wavelength multiplexed signal output from the wavelength group multiplexer.

11. The optical transmission device according to claim 1, further comprising: a second optical signal source generating an optical signal having a shorter wavelength than the optical signal multiplexed and output by said wavelength group multiplexer; and second optical multiplexing means further configured to multiplex the optical signal having the shorter wavelength and the optical signal multiplexed by the wavelength group multiplexer, and to propagate the optical signal having the shorter wavelength in the same direction as the multiplexed optical signal.

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