Optical output module, optical output system, and optical output method

Abstract

An optical output module according to the present disclosure comprises: a first dummy light source that outputs first dummy light in a first wavelength band; a second dummy light source that outputs second dummy light in a second wavelength band different from the first wavelength band; an optical switch into which the first dummy light and the second dummy light are input; and a control means that outputs a switching instruction to the optical switch. The optical switch outputs a combined light obtained by combining the first dummy light and the second dummy light while, in accordance with the switching instruction, gradually increasing an attenuation amount for the first dummy light and gradually decreasing an attenuation amount for the second dummy light.

Description

Light output module, light output system, and light output method

[0001] The present disclosure relates to a light output module, a light output system, and a light output method.

[0002] FIG. 1 is a diagram illustrating an example of optical level versus wavelength characteristics of an optical signal transmitted through an optical transmission line OL when the optical transmission line OL is normal. In FIG. 1, the upper diagram shows an example in which an optical signal is transmitted by single-band transmission using the C-band, and the lower diagram shows an example in which an optical signal is transmitted by multi-band transmission using the C-band and the L-band (the same applies to FIG. 2 hereinafter).

[0003] Furthermore, in FIG. 1, for the optical level versus wavelength characteristics in the drawing, the horizontal axis represents wavelength and the vertical axis represents optical level (the same applies to FIG. 2 and FIG. 4 hereinafter). Furthermore, in FIG. 1, the optical signal is assumed to be transmitted in a direction from left to right in the drawing (the same applies to FIG. 2 and FIG. 4 hereinafter).

[0004] As shown in FIG. 1, when an optical signal is transmitted through an optical transmission line OL, stimulated Raman scattering (SRS: Stimulated Raman Scattering) occurs, and the optical level versus wavelength characteristic of the optical signal changes in a tilted manner under the influence of SRS.

[0005] The tilted optical level versus wavelength characteristic is generated by energy transition from the short wavelength side to the long wavelength side in an optical signal transmitted through the optical transmission line OL. Furthermore, the wider the wavelength band of the optical signal transmitted through the optical transmission line OL and the higher the optical level of the optical signal transmitted through the optical transmission line OL, the greater the amount of energy that the optical signal gives to the optical transmission line OL and the amount of energy that the optical signal receives from the optical transmission line OL. As a result, the tilt of the optical level versus wavelength characteristic increases (that is, the tilt angle increases). Therefore, in the case of multi-band transmission, the tilt of the optical level versus wavelength characteristic is larger compared to single-band transmission.

[0006] Furthermore, when a disconnection occurs in the optical transmission line OL, the optical level of the optical signal transmitted through the optical transmission line OL fluctuates greatly (decreases), and the optical level may deviate from the design value.

[0007] Figure 2 illustrates an example of the optical level versus wavelength characteristics of an optical signal transmitted through the optical transmission path OL when a break occurs in the optical transmission path OL. As shown in Figure 2, when a break occurs in the optical transmission path OL, the optical signal transmitted through the optical transmission path OL has a narrow wavelength bandwidth and a low optical level. As a result, the tilt-shaped optical level versus wavelength characteristics change transiently, and ultimately, optical signals other than the longest wavelength optical signal are blocked, and the optical level of the longest wavelength optical signal also fluctuates (decreases) significantly. Furthermore, in the case of multiband transmission, the fluctuation in the optical level of the longest wavelength optical signal becomes larger compared to single-band transmission.

[0008] Therefore, especially in multiband transmission, a challenge is to suppress fluctuations in the optical level of the optical signal transmitted through the optical transmission line OL when a break occurs in the optical transmission line OL. Recently, however, the insertion of dummy light as compensation light (ASE (Amplified Spontaneous Emission) light) into the optical transmission line OL has been considered in order to suppress fluctuations in the optical level of the optical signal transmitted through the optical transmission line OL. In addition, dummy light may also be inserted into the optical transmission line OL to keep the effect of stimulated Raman scattering constant. For example, Patent Document 1 discloses a technique that uses multiple dummy lights having different center wavelengths.

[0009] International Publication No. 2020 / 121716

[0010] However, when using multiple dummy lights, as in the technology disclosed in Patent Document 1, momentary interruptions in the optical signal may occur when switching between dummy lights. In this case, if multiband transmission is being performed, a momentary interruption in the optical signal due to switching of dummy lights in one wavelength band can cause fluctuations in the optical signal in another wavelength band, which is a problem.

[0011] Therefore, in view of the above-mentioned problems, the purpose of this disclosure is to provide an optical output module, an optical output system, and an optical output method that can avoid momentary interruptions of the optical signal when switching dummy light.

[0012] An optical output module according to one embodiment includes: a first dummy light source that outputs a first dummy light in a first wavelength band; a second dummy light source that outputs a second dummy light in a second wavelength band different from the first wavelength band; an optical switch to which the first dummy light and the second dummy light are input; and a control means that outputs a switching instruction to the optical switch. The optical switch outputs a combined light obtained by combining the first dummy light and the second dummy light, while gradually increasing the attenuation amount for the first dummy light and gradually decreasing the attenuation amount for the second dummy light, in response to the switching instruction.

[0013] An optical output system according to one embodiment includes: an optical output module; a second optical output module equipped with a third dummy light source that outputs a third dummy light in a third wavelength band different from the first and second wavelength bands; and a multiplexer that outputs combined light obtained by combining the output light of the optical output module and the output light of the second optical output module.

[0014] One embodiment of the optical output method is an optical output method performed by an optical output module, the optical output module comprising: a first dummy light source that outputs a first dummy light in a first wavelength band; a second dummy light source that outputs a second dummy light in a second wavelength band different from the first wavelength band; an optical switch into which the first dummy light and the second dummy light are input; and a control means, the optical output method includes the control means outputting a switching instruction to the optical switch; and the optical switch outputting a combined light obtained by combining the first dummy light and the second dummy light, while gradually increasing the attenuation amount for the first dummy light and gradually decreasing the attenuation amount for the second dummy light in response to the switching instruction.

[0015] According to the above-described embodiment, the effect is obtained that an optical output module, an optical output system, and an optical output method can be provided that can avoid momentary interruptions of the optical signal when switching dummy light.

[0016] This figure illustrates an example of the optical level versus wavelength characteristics of an optical signal transmitted through an optical transmission path when the optical transmission path is functioning normally. This figure illustrates an example of the optical level versus wavelength characteristics of an optical signal transmitted through an optical transmission path when a break occurs in the optical transmission path. This figure shows an example of the configuration of an optical output module according to this disclosure. This figure illustrates an example of the pattern of an optical signal output from an optical output module according to this disclosure. This figure illustrates an example of the time progression of the optical level of an optical signal output from an optical switch when switching ASE light in an optical output module according to this disclosure. This is a flowchart illustrating an example of the operation flow when switching ASE light in an optical output module according to this disclosure. This figure shows an example of the configuration of an optical output module according to this disclosure. This is a flowchart illustrating an example of the operation flow when switching dummy light in an optical output module according to this disclosure. This is a block diagram illustrating an example of the configuration of an optical output system according to this disclosure. This is a block diagram illustrating an example of the hardware configuration of a computer that implements the optical output module according to this disclosure.

[0017] Embodiments of the present disclosure will be described below with reference to the drawings. Note that the following description and drawings have been omitted and simplified as appropriate for clarity of explanation. Furthermore, in the following drawings, the same elements are denoted by the same reference numerals, and redundant explanations have been omitted where necessary.

[0018] <Embodiment 1> First, the configuration of the optical output module 10 according to the present disclosure will be described. Figure 3 is a diagram showing an example of the configuration of the optical output module 10 according to the present disclosure. As shown in Figure 3, the optical output module 10 is a module capable of transmitting optical signals by multiband transmission using the C band and the L band. The optical output module 10 is to be placed in the middle of the optical transmission path OL. In the following description, the C band and the L band are used, but the description is not limited to these. As long as the wavelengths are different, other bands (for example, the S band) may be used.

[0019] The optical output module 10 includes, as components for the C band, a Ch ASE light source 111, an optical transceiver 112, a WSS (Wavelength Selective Switch) 113, and an optical amplifier 114. The optical output module 10 also includes, as components for the L band, a Bulk ASE light source 121, a Ch ASE light source 122, an optical transceiver 123, a WSS 124, an optical amplifier 125, and an optical switch 126. Furthermore, the optical output module 10 includes a control unit 131.

[0020] In this disclosure, dummy light is inserted into the optical transmission path OL as compensation light (ASE light). Bulk ASE light is the ASE light output from the light source itself. Ch ASE light is ASE light that has been wavelength-selected by the subsequent WSS after being output from the light source.

[0021] The Ch ASE light source 111 outputs ASE light that becomes Ch ASE light. The ASE light output from the Ch ASE light source 111 is wavelength-selected by the WSS 113 to become Ch ASE light. The optical transceiver 112 outputs the main signal (indicated as "Signal" in the figure; the same applies hereafter).

[0022] The WSS113 either outputs the main signal output from the optical transceiver 112, or outputs combined light obtained by combining the main signal output from the optical transceiver 112 with Ch ASE light selected from the Ch ASE light source 111.

[0023] Here, the wavelength information of the optical transceiver 112 is registered in the WSS 113 by the control unit 131. When the WSS 113 outputs the combined light described above, it takes ASE light in the C band that does not include the wavelength of the optical transceiver 112 as Ch ASE light and combines this Ch ASE light with the main signal. The optical amplifier 114 amplifies the optical signal (main signal or combined light) output from the WSS 113.

[0024] The Bulk ASE light source 121 outputs ASE light that becomes Bulk ASE light. When using Bulk ASE light, the subsequent WSS and optical amplifier are not required compared to when using Ch ASE light, thus reducing costs.

[0025] The Ch ASE light source 122 outputs ASE light that becomes Ch ASE light. The ASE light output from the Ch ASE light source 122 is wavelength-selected by the WSS 124 to become Ch ASE light.

[0026] Here, the ASE light output from the Bulk ASE light source 121 and the ASE light output from the Ch ASE light source 122 may be the same. Therefore, the Bulk ASE light source 121 and the Ch ASE light source 122 may be common to each other. The optical transceiver 123 outputs the main signal.

[0027] The WSS124 either outputs the main signal output from the optical transceiver 123, or outputs combined light obtained by combining the main signal output from the optical transceiver 123 with Ch ASE light selected from the Ch ASE light source 122.

[0028] Here, the wavelength information of the optical transceiver 123 is registered in the WSS 124 by the control unit 131. When the WSS 124 outputs the combined light described above, it takes ASE light in the L band that does not include the wavelength of the optical transceiver 123 as Ch ASE light and combines this Ch ASE light with the main signal. The optical amplifier 125 amplifies the optical signal (main signal or combined light) output from the WSS 124.

[0029] The optical switch 126 selects either the Bulk ASE light output from the Bulk ASE light source 121 or the optical signal (main signal or combined light) output from the optical amplifier 125, and outputs the selected signal as optical output.

[0030] The optical output module 10 outputs combined light, which is obtained by combining the optical signal output from the optical amplifier 125 and the optical signal output from the optical switch 126.

[0031] Figure 4 illustrates an example of an optical signal pattern output from the optical output module 10 according to this disclosure. As shown in Figure 4, there are four possible patterns for the optical signal output from the optical output module 10.

[0032] Pattern 1 is a pattern in which the combined light of the main signal and Ch ASE light is output as a C-band optical signal, and the Bulk ASE light is output as an L-band optical signal. Pattern 2 is a pattern in which the main signal is output as a C-band optical signal, and the Bulk ASE light is output as an L-band optical signal. Pattern 3 is a pattern in which the main signal is output as a C-band optical signal, and the combined light of the main signal and Ch ASE light is output as an L-band optical signal. Pattern 4 is a pattern in which the main signal is output as a C-band optical signal, and the main signal is output as an L-band optical signal.

[0033] Of these, patterns 1 and 2 are patterns that do not use the L band. In other words, patterns 1 and 2 are patterns for single-band transmission using the C band. On the other hand, patterns 3 and 4 are patterns that use both the C band and the L band. In other words, patterns 3 and 4 are patterns for multi-band transmission using the C band and the L band.

[0034] Note that while the shape of the Ch ASE light in Figure 4 is shown as a strip, it is not limited to this. Depending on the settings of the subsequent WSS, the shape of the Ch ASE light can also be narrower, such as a Bulk ASE light that does not overlap with the wavelength of the main signal.

[0035] Here, for example, the output of the optical output module 10 may transition in the order of pattern 1 → 2 → 3 → 4. In this case, when transitioning from pattern 2 to 3, a switch occurs on the L-band side from Bulk ASE light to combined light of the main signal and Ch ASE light. During this switch, the L-band optical signal may be momentarily interrupted, causing the C-band optical signal to fluctuate.

[0036] Therefore, in this disclosure, an optical switch with crosstalk is used as the optical switch 126. An optical switch with crosstalk is, for example, a MEMS (Micro Electro Mechanical Systems) switch.

[0037] The specific operation of the optical switch 126 when switching ASE light is as follows. For example, when switching from Bulk ASE light to a combined light of the main signal and Ch ASE light, the optical switch 126 gradually increases the attenuation for Bulk ASE light and gradually decreases the attenuation for the combined light of the main signal and Ch ASE light, outputting a combined light obtained by combining Bulk ASE light and the combined light of the main signal and Ch ASE light. At this time, the optical switch 126 adjusts so that the sum of the attenuation for Bulk ASE light and the attenuation for the combined light of the main signal and Ch ASE light remains constant. Finally, the optical switch 126 outputs a combined light of the main signal and Ch ASE light.

[0038] Figure 5 illustrates an example of the time progression of the optical level of the optical signal output from the optical switch 126 when switching ASE light in the optical output module 10 according to this disclosure. Figure 5 is an example of switching Bulk ASE light to combined light of the main signal and Ch ASE light.

[0039] As shown in Figure 5, when switching the Bulk ASE light to a combined light of the main signal and Ch ASE light, the optical switch 126 performs the operation described above, so that the L-band optical signal does not drop to the point of signal interruption. Therefore, momentary interruptions in the L-band optical signal are avoided, and as a result, fluctuations in the C-band optical signal are also avoided.

[0040] Furthermore, the output of the optical output module 10 may transition in the order of pattern 4 → 3 → 2 → 1. In this case, when transitioning from pattern 3 to 2, a switch occurs on the L-band side from the combined light of the main signal and Ch ASE light to the Bulk ASE light. During this switch, the optical switch 126 also performs the same operation as described above in order to avoid momentary interruption of the L-band optical signal. That is, the optical switch 126 gradually increases the attenuation for the combined light of the main signal and Ch ASE light, and gradually decreases the attenuation for the Bulk ASE light, while outputting a combined light obtained by combining the combined light of the main signal and Ch ASE light and the Bulk ASE light.

[0041] The control unit 131 controls each component within the optical output module 10. For example, when switching AES light on the L-band side, the control unit 131 outputs a switching instruction to the optical switch 126 and controls the optical switch 126 to perform the operations described above. The control unit 131 also registers the wavelength information of the optical transceiver 112 in the WSS 113 and the wavelength information of the optical transceiver 123 in the WSS 124.

[0042] Furthermore, the control unit 131 may monitor the light level of the ASE light output from the Bulk ASE light source 121 and determine whether or not the Bulk ASE light source 121 has deteriorated based on the monitored light level. In this case, for example, the control unit 131 may determine that the Bulk ASE light source 121 has deteriorated if the light level is below a threshold.

[0043] Furthermore, the control unit 131 may determine whether or not the L-band is being used and notify the user of the result of this determination on an unillustrated display unit. For example, the control unit 131 may determine that the L-band is being used if the wavelength information of the optical transceiver 123 is registered in the WSS 124. Also, the control unit 131 may determine that the L-band is not being used when the optical switch 126 has selected the Bulk ASE light output from the Bulk ASE light source 121, and determine that the L-band is being used when the optical switch 126 has selected the optical signal (main signal or combined light) output from the optical amplifier 125.

[0044] Next, the operation when switching ASE light in the optical output module 10 according to the present disclosure will be described in detail. FIG. 6 is a flow chart illustrating an example of the operation flow when switching ASE light in the optical output module 10 according to the present disclosure. Note that FIG. 6 is an operation example when switching Bulk ASE light to multiplexed light of a main signal and Ch ASE light.

[0045] As shown in FIG. 6, first, the control unit 131 registers the wavelength information of the optical transceiver 123 in the WSS 124 (step S101). In response to this, the WSS 124 uses, as Ch ASE light, ASE light in a wavelength band of the L band that does not include the wavelength of the optical transceiver 123, and multiplexes the Ch ASE light with the main signal.

[0046] Next, the control unit 131 activates the optical amplifier 125 that has been shut down when Bulk ASE light is selected (step S102). Next, the control unit 131 monitors whether or not the optical level of the optical signal output from the optical amplifier 125 (the multiplexed light of the main signal and the Ch ASE light) is equal to the optical level of the Bulk ASE light (step S103). This is to suppress the tilt of the optical level versus wavelength characteristic of the optical signal due to the insertion of Ch ASE light.

[0047] Next, when the optical level of the optical signal output from the optical amplifier 125 (the multiplexed light of the main signal and the Ch ASE light) becomes equal to the optical level of the Bulk ASE light, the control unit 131 outputs a switching instruction to the optical switch 126 instructing to switch Bulk ASE light to the multiplexed light of the main signal and Ch ASE light (step S104).

[0048] Thereafter, based on the above switching instruction, the optical switch 126 gradually increases the attenuation for Bulk ASE light and gradually decreases the attenuation for the multiplexed light of the main signal and Ch ASE light, while outputting multiplexed light obtained by multiplexing Bulk ASE light and the multiplexed light of the main signal and Ch ASE light (step S105). Finally, the optical switch 126 ends up outputting the multiplexed light of the main signal and Ch ASE light.

[0049] Here, before switching the ASE light in Figure 6 (while selecting Bulk ASE light), the optical amplifier 125 is shut down, as described above. Therefore, the Ch ASE light source 122 may be outputting ASE light.

[0050] Furthermore, after the ASE light switching in Figure 6 (while selecting the combined light of the main signal and Ch ASE light), even if ASE light is output from the Bulk ASE light source 121, that ASE light is blocked or attenuated by the optical switch 126. Therefore, the Bulk ASE light source 121 may be outputting ASE light.

[0051] As described above, according to this embodiment 1, for example, when switching from Bulk ASE light to a combined light of the main signal and Ch ASE light on the L-band side, the optical switch 126 gradually increases the attenuation for Bulk ASE light and gradually decreases the attenuation for the combined light of the main signal and Ch ASE light, while outputting a combined light obtained by combining Bulk ASE light and the combined light of the main signal and Ch ASE light. This makes it possible to avoid momentary interruptions in the L-band optical signal. As a result, it is also possible to avoid fluctuations in the C-band optical signal.

[0052] <Embodiment 2> This second embodiment corresponds to an embodiment that expands upon the first embodiment described above. First, the configuration of the optical output module 20 according to this disclosure will be described. Figure 7 is a block diagram showing an example of the configuration of the optical output module 20 according to this disclosure. As shown in Figure 7, the optical output module 20 includes a first dummy light source 211, a second dummy light source 212, an optical switch 213, and a control unit 221.

[0053] The first dummy light source 211 outputs first dummy light in a first wavelength band. The first dummy light source 211 corresponds to the light source 121 for Bulk ASE light. The second dummy light source 212 outputs second dummy light in a second wavelength band different from the first wavelength band. The second dummy light source 212 corresponds to the combination of the light source 122 for Ch ASE light and WSS 124.

[0054] Optical switch 213 receives the first dummy light and the second dummy light as inputs. Optical switch 213 corresponds to optical switch 126. Control unit 221 outputs a switching instruction to optical switch 213. Control unit 221 corresponds to control unit 131. Then, in response to the switching instruction, optical switch 213 gradually increases the attenuation amount for the first dummy light and gradually decreases the attenuation amount for the second dummy light, and outputs a combined light obtained by combining the first dummy light and the second dummy light.

[0055] Next, the operation of the optical output module 20 according to this disclosure when switching dummy lights will be described. Figure 8 is a flowchart illustrating an example of the operation flow when switching dummy lights in the optical output module 20 according to this disclosure. Figure 8 is an example of the operation when switching from the first dummy light to the second dummy light.

[0056] As shown in Figure 8, the control unit 221 outputs a switching instruction to the optical switch 213, instructing it to switch the first dummy light to the second dummy light (step S201). Then, based on the above switching instruction, the optical switch 213 gradually increases the attenuation for the first dummy light and gradually decreases the attenuation for the second dummy light, outputting a combined light obtained by combining the first dummy light and the second dummy light (step S202). This makes it possible to avoid momentary interruptions in the optical signal when switching from the first dummy light to the second dummy light.

[0057] The optical switch 213 may be controlled by the control unit 221 so that the sum of the attenuation amounts for the first dummy light and the attenuation amounts for the second dummy light remains constant. The optical output module 20 may also include an optical transceiver that outputs an optical signal of a predetermined wavelength which is combined with the second dummy light. This optical transceiver corresponds to the optical transceiver 123. In this case, the control unit 221 may register wavelength information based on the predetermined wavelength with the second dummy light source 212. The second dummy light source 212 may also output a second dummy light in a second wavelength band that does not include the predetermined wavelength.

[0058] Furthermore, the second dummy light source 212 may include a light source and a wavelength selection switch that outputs light in a second wavelength band that does not include a predetermined wavelength from the light output from the light source as a second dummy light. This light source corresponds to the Ch ASE light source 122, and this wavelength selection switch corresponds to the WSS 124. In this case, this light source and the first dummy light source 211 may be the same.

[0059] Furthermore, the control unit 221 may monitor the light level of the first dummy light source 211 and determine whether or not the first dummy light source 211 has deteriorated based on the monitored light level.

[0060] <Embodiment 3> Figure 9 is a block diagram showing an example configuration of the optical output system 50 according to the present disclosure. As shown in Figure 9, the optical output system 50 includes the optical output module 20 shown in Figure 7, a second optical output module 30, and a multiplexer 40.

[0061] The second optical output module 30 includes a third dummy light source 311 that outputs a third dummy light in a third wavelength band different from the first and second wavelength bands. The third dummy light source 311 corresponds to a combination of the Ch ASE light source 111 and the WSS 113. The multiplexer 40 outputs combined light obtained by combining the output light of the optical output module 20 and the output light of the second optical output module 30.

[0062] The control unit 221 may determine whether the first wavelength band and the second wavelength band are being used and display the result of that determination. In this case, the control unit 221 may determine that the first wavelength band and the second wavelength band are being used if wavelength information is registered in the second dummy light source 212. Alternatively, the control unit 221 may determine whether the first wavelength band and the second wavelength band are being used based on the output light of the optical switch 213.

[0063] <Hardware Configuration of the Disclosure> Next, the hardware configuration of the computer 90 that implements the optical output module according to the disclosure (including the optical output module 10, optical output module 20, and second optical output module 30 described above; the same applies hereinafter) will be described. Figure 10 is a block diagram showing an example of the hardware configuration of the computer 90 that implements the optical output module according to the disclosure.

[0064] As shown in Figure 10, the computer 90 includes a processor 91, memory 92, storage 93, input / output interface (I / F) 94, and communication interface (Communication I / F) 95. The processor 91, memory 92, storage 93, input / output interface 94, and communication interface 95 are connected to each other by data transmission paths for sending and receiving data.

[0065] The processor 91 is a processing unit such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The memory 92 is a memory such as RAM (Random Access Memory) or ROM (Read Only Memory). The storage 93 is a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or memory card. The storage 93 may also be a memory such as RAM or ROM.

[0066] A program is stored in the storage 93. This program includes a set of instructions (or software code) that, when loaded into a computer, causes the computer 90 to perform one or more functions in the optical output module according to this disclosure. The components of the optical output module according to this disclosure may be realized by the processor 91 loading and executing the program stored in the storage 93. The storage function of the optical output module according to this disclosure may also be realized by memory 92 or storage 93.

[0067] Furthermore, the programs described above may be stored on non-temporary computer-readable media or tangible storage media. Examples, but not limited to, include RAM, ROM, flash memory, SSD, or other memory technologies; CD (Compact Disc)-ROM, DVD (Digital Versatile Disc), Blu-ray® disc, or other optical disc storage; magnetic cassettes, magnetic tapes, magnetic disk storage, or other magnetic storage devices. The programs may also be transmitted over temporary computer-readable media or communication media. Examples, but not limited to, include temporary computer-readable media or communication media, including electrical, optical, acoustic, or other forms of transmitted signals.

[0068] The input / output interface 94 is connected to a display device 941, an input device 942, a sound output device 943, and the like. The display device 941 is a device that displays a screen corresponding to the drawing data processed by the processor 91, such as an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, or a monitor. The input device 942 is a device that receives operator input, such as a keyboard, mouse, and touch sensor. The display device 941 and the input device 942 may be integrated and implemented as a touch panel. The sound output device 943 is a device that outputs sound corresponding to the acoustic data processed by the processor 91, such as a speaker.

[0069] The communication interface 95 transmits and receives data to and from an external device. For example, the communication interface 95 communicates with an external device via a wired communication path or a wireless communication path.

[0070] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0071] Furthermore, each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated not only with one specific embodiment but also with one or more other embodiments. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps described in any of the drawings may be changed as appropriate.

[0072] Furthermore, some or all of the embodiments described above may also be described as follows, but are not limited to the following: (Note 1) An optical output module comprising: a first dummy light source that outputs a first dummy light in a first wavelength band; a second dummy light source that outputs a second dummy light in a second wavelength band different from the first wavelength band; an optical switch into which the first dummy light and the second dummy light are input; and a control means that outputs a switching instruction to the optical switch, wherein the optical switch outputs a combined light obtained by combining the first dummy light and the second dummy light, while gradually increasing the attenuation amount for the first dummy light and gradually decreasing the attenuation amount for the second dummy light in response to the switching instruction. (Note 2) The optical output module according to Note 1, wherein the optical switch is controlled by the control means such that the sum of the attenuation amounts for the first dummy light and the attenuation amounts for the second dummy light is constant. (Note 3) The optical output module according to Note 1, further comprising an optical transceiver that outputs an optical signal of a predetermined wavelength which is combined with the second dummy light, wherein the control means registers wavelength information based on the predetermined wavelength to the second dummy light source, and the second dummy light source outputs the second dummy light in the second wavelength band which does not include the predetermined wavelength. (Note 4) The optical output module according to Note 3, wherein the second dummy light source comprises a light source and a wavelength selection switch that outputs light in the second wavelength band which does not include the predetermined wavelength from the light output from the light source as the second dummy light. (Note 5) The optical output module according to Note 4, wherein the first dummy light source and the light source are common. (Note 6) The optical output module according to Note 3, wherein the control means monitors the light level of the first dummy light source and determines whether or not the first dummy light source has deteriorated based on the monitored light level.(Note 7) An optical output system comprising: an optical output module as described in Note 3; a second optical output module equipped with a third dummy light source that outputs a third dummy light in a third wavelength band different from the first and second wavelength bands; and a multiplexer that outputs combined light obtained by combining the output light of the optical output module and the output light of the second optical output module. (Note 8) The optical output system as described in Note 7, wherein the control means determines whether or not the first and second wavelength bands are being used and displays the result of the determination. (Note 9) The optical output system as described in Note 8, wherein the control means determines that the first and second wavelength bands are being used if the wavelength information is registered in the second dummy light source. (Note 10) The optical output system as described in Note 8, wherein the control means determines whether or not the first and second wavelength bands are being used based on the output light of the optical switch. (Note 11) An optical output method performed by an optical output module, the optical output module comprising: a first dummy light source that outputs a first dummy light in a first wavelength band; a second dummy light source that outputs a second dummy light in a second wavelength band different from the first wavelength band; an optical switch into which the first dummy light and the second dummy light are input; and a control means, the optical output method comprising: the control means outputting a switching instruction to the optical switch; and the optical switch outputting a combined light obtained by combining the first dummy light and the second dummy light, while gradually increasing the attenuation amount for the first dummy light and gradually decreasing the attenuation amount for the second dummy light in response to the switching instruction.

[0073] Furthermore, some or all of the elements (e.g., configuration and function) described in Appendices 2 to 6 that are subordinate to Appendice 1 may also be subordinate to Appendices 7 and 11 in the same way as those described in Appendices 2 to 6. Similarly, some or all of the elements (e.g., configuration and function) described in Appendices 8 to 10 that are subordinate to Appendice 7 may also be subordinate to Appendices 1 and 11 in the same way as those described in Appendices 8 to 10. Some or all of the elements described in any appendice may be applied to various hardware, software, recording means, systems, and methods for recording software.

[0074] 10 Optical output module 111 Ch ASE light source 112 Optical transceiver 113 WSS 114 Optical amplifier 121 Bulk ASE light source 122 Ch ASE light source 123 Optical transceiver 124 WSS 125 Optical amplifier 126 Optical switch 131 Control unit 20 Optical output module 211 First dummy light source 212 Second dummy light source 213 Optical switch 221 Control unit 30 Second optical output module 311 Third dummy light source 40 Multiplexer 50 Optical output system 90 Computer 91 Processor 92 Memory 93 Storage 94 Input / output interface 941 Display device 942 Input device 943 Sound output device 95 Communication interface OL Optical transmission line

Claims

1. An optical output module comprising: a first dummy light source that outputs a first dummy light in a first wavelength band; a second dummy light source that outputs a second dummy light in a second wavelength band different from the first wavelength band; an optical switch into which the first dummy light and the second dummy light are input; and a control means that outputs a switching instruction to the optical switch, wherein the optical switch outputs a combined light obtained by combining the first dummy light and the second dummy light, while gradually increasing the attenuation amount for the first dummy light and gradually decreasing the attenuation amount for the second dummy light in response to the switching instruction.

2. The optical switch is controlled by the control means such that the sum of the attenuation amount for the first dummy light and the attenuation amount for the second dummy light is constant, as described in claim 1.

3. The optical output module according to claim 1, further comprising an optical transceiver that outputs an optical signal of a predetermined wavelength which is combined with the second dummy light, wherein the control means registers wavelength information based on the predetermined wavelength with the second dummy light source, and the second dummy light source outputs the second dummy light in the second wavelength band which does not include the predetermined wavelength.

4. The optical output module according to claim 3, wherein the second dummy light source comprises a light source and a wavelength selection switch that outputs light in a second wavelength band that does not include the predetermined wavelength from the light source as the second dummy light.

5. The optical output module according to claim 4, wherein the first dummy light source and the light source are common.

6. The optical output module according to claim 3, wherein the control means monitors the light level of the first dummy light source and determines whether or not the first dummy light source has deteriorated based on the monitored light level.

7. An optical output system comprising: an optical output module according to claim 3; a second optical output module having a third dummy light source that outputs a third dummy light in a third wavelength band different from the first and second wavelength bands; and a multiplexer that outputs combined light obtained by combining the output light of the optical output module and the output light of the second optical output module.

8. The optical output system according to claim 7, wherein the control means determines whether or not the first wavelength band and the second wavelength band are being used and displays the result of the determination.

9. The optical output system according to claim 8, wherein the control means determines that the first wavelength band and the second wavelength band are being used when the wavelength information is registered in the second dummy light source.

10. The optical output system according to claim 8, wherein the control means determines whether or not to use the first wavelength band and the second wavelength band based on the output light of the optical switch.

11. An optical output method performed by an optical output module, the optical output module comprising: a first dummy light source that outputs a first dummy light in a first wavelength band; a second dummy light source that outputs a second dummy light in a second wavelength band different from the first wavelength band; an optical switch into which the first dummy light and the second dummy light are input; and a control means, the optical output method comprising: the control means outputting a switching instruction to the optical switch; and the optical switch outputting a combined light obtained by combining the first dummy light and the second dummy light, while gradually increasing the attenuation amount for the first dummy light and gradually decreasing the attenuation amount for the second dummy light in response to the switching instruction.

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