JP2012175247A - Wavelength adjustment system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength adjustment system and method which, when using a circling AWG as an optical switch, can simply set plural kinds of wavelengths used as optical signals.SOLUTION: A wavelength adjustment system comprises a wavelength variable light source which outputs light in N kinds of wavelengths whose wavelength can be changed from the outside; a 1-to-N branching coupler which branches the light output from the wavelength variable light source into N rays and supplies them to respective input ports of an array waveguide diffraction grating; an optical power meter which measures the wavelength and power of rays of light output from the output ports of the array waveguide diffraction grating; and a wavelength adjustment device which determines wavelengths utilized in the array waveguide diffraction grating. The wavelength adjustment device receives the wavelength and power values of rays of light measured by the optical power meter and determines adjusted wavelengths corresponding to N kinds of standard wavelengths respectively, where a difference in optical power between rays of light output from the output ports of the array waveguide diffraction grating is minimum.

Description

  The present invention relates to a wavelength adjustment for adjusting the wavelength of an optical signal, suitable for an optical switch using an arrayed waveguide grating (AWG) (hereinafter referred to as a circulatory AWG) having a wavelength circulation property. The present invention relates to a system and method.

  Currently, wavelength division multiplexing technology for multiplexing and transmitting a plurality of optical signals having different wavelengths is employed in a trunk line communication network. In such a trunk-line communication network, it is expected to put into practical use an optical packet switch that switches a packet (optical packet) modulated into an optical signal in the order of nanoseconds as light.

  The optical packet switch is required to have a large-scale optical switch with N (N is a positive integer) input and N output (N × N) so that more ground-to-ground communication is possible. As such an N × N optical switch, a wavelength selection type optical switch that includes a plurality of wavelength variable light sources and wavelength multiplexers / demultiplexers, and enables multiple connection of optical signals of different wavelengths allocated to each port. However, it is proposed in Patent Document 1, for example. The wavelength selection type optical switch can switch the port for outputting an optical signal according to the wavelength of light output from a plurality of variable wavelength light sources.

  In recent years, as a wavelength selective optical switch, a revolving AWG having a wavelength revolving property has been put into practical use, and it is considered that a large-scale optical packet switch using the recurring AWG will become widespread in the future. “Wavelength recursion” means that in an optical multiplexing / demultiplexing circuit having a plurality (N) of input ports and a plurality (N) of output ports, optical signals of the same wavelength input from different ports are excessive or insufficient. Optical multiplexing / demultiplexing characteristics that always output from different output ports. The recursive AWG functions to distribute the wavelength-multiplexed optical signal input to each input port to different output ports according to the wavelength of light. Which optical signal of which wavelength is distributed to which output port is set in advance for each input port. Therefore, if the number of wavelengths of the optical signal and the number of input / output ports are kept the same, and the wavelength of the optical signal output from each output port is set to be different for each input port, the input / output port will be used. Thus, a plurality of nodes that transmit and receive optical signals can be connected with a full mesh.

JP-A-5-244649

  In general, the circulatory AWG has a difference in transmission wavelength between input / output ports, and the attenuation factor of power differs between input / output ports. That is, even if light having the same wavelength and power is input from each input port, a difference occurs in the power of light output from each output port.

  For example, a receiver that receives an optical signal that has passed through a circulating AWG tends to have a faster response speed as the dynamic range is smaller. Therefore, it is desirable that the difference in the power of light output from each output port be as small as possible. .

  For such a problem, for example, in a plurality of light sources (variable wavelength light sources) that generate light of each wavelength input to the recursive AWG, the output wavelengths are adjusted according to the wavelength shift between the input and output ports. A method is conceivable. However, in such a method, when preparing a spare wavelength tunable light source in preparation for a failure or the like, it is necessary to adjust the wavelength of the spare wavelength tunable light source provided for each input / output port. Becomes very cumbersome.

  In general, the circulating AWG has a transmission band having a constant period (grid interval) and transmits a modulated optical signal for each wavelength, and a wavelength band having a predetermined width around the transmission peak. Each has a transmission filter characteristic that transmits an optical signal. In this transmission filter characteristic, there is an overlapping region between adjacent wavelength bands, so that an optical signal leaks to an unintended output port. If the power of this leaked light is larger than the light receiving threshold value for determining the signal light including information, information to be transmitted in other wavelength bands is mixed in the received optical signal. A bit error occurs in the optical signal.

  Therefore, when using the recursive AWG as an optical switch, considering the difference in power attenuation for each input / output port and the overlap of transmission filter characteristics, a plurality of types of wavelengths used as optical signals are respectively used. It is desirable that it can be set easily.

  The present invention has been made in order to solve the problems of the background art as described above, and when using the recursive AWG as an optical switch, a wavelength capable of easily setting a plurality of types of wavelengths used as an optical signal. An object is to provide an adjustment system and method.

In order to achieve the above object, the wavelength tuning system of the present invention has the following formula:
Wavelength adjustment for determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, used in an arrayed waveguide diffraction grating having wavelength recurring characteristics, including N input ports and output ports A system,
A wavelength tunable light source capable of changing the wavelength from the outside and outputting light of the N types of wavelengths;
A 1-to-N branch coupler for branching light output from the wavelength tunable light source into N branches and supplying the light to the input ports of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
The wavelength and power values of light measured by the optical power meter are received, and the light of the N types of standard wavelengths that minimizes the difference in power of light output from the output port of the arrayed waveguide grating is obtained. A wavelength adjusting device for determining a corresponding adjusted wavelength, and
Have

Or when N is a positive integer,
Wavelength adjustment for determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, used in an arrayed waveguide diffraction grating having wavelength recurring characteristics, including N input ports and output ports A system,
A wavelength tunable light source that can change the wavelength from the outside and supplies the light of the N types of wavelengths to the input port of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
The light wavelength and power values measured by the optical power meter are received, and the power of light leaking from an unintended output port that does not correspond to the standard wavelength among the output ports of the arrayed waveguide grating is minimized. , A wavelength adjustment device that determines an adjusted wavelength corresponding to each of the N types of standard wavelengths, and
Have

On the other hand, in the wavelength adjustment method of the present invention, when N is a positive integer,
For determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, which is used in an arrayed waveguide grating having a wavelength circulation property, which has N input ports and output ports. A wavelength adjustment method,
A wavelength tunable light source capable of changing the wavelength from the outside and outputting light of the N types of wavelengths;
A 1-to-N branch coupler for branching light output from the wavelength tunable light source into N branches and supplying the light to the input ports of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
With
Receiving the wavelength and power values of the light measured by the optical power meter;
In this method, the adjusted wavelengths corresponding to the N kinds of standard wavelengths of light that minimize the difference in power of the light output from the output port of the arrayed waveguide grating are respectively determined.

Or when N is a positive integer,
For determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, which is used in an arrayed waveguide grating having a wavelength circulation property, which has N input ports and output ports. A wavelength adjustment method,
A wavelength tunable light source that can change the wavelength from the outside and supplies the light of the N types of wavelengths to the input port of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
With
Receiving the wavelength and power values of the light measured by the optical power meter;
Of the output ports of the arrayed waveguide grating, the adjusted wavelengths corresponding to the light of the N types of standard wavelengths are determined so that the power of light leaking from an unintended output port that does not correspond to the standard wavelength is minimized. It is a method to do.

  In the wavelength adjustment system and method as described above, since only one wavelength tunable light source is required, N wavelengths (adjusted wavelengths) common to each input / output port used in the N × N revolving AWG to be measured are used. Can be determined efficiently. In addition, even when a standby wavelength tunable light source is prepared, it is only necessary to set the transmission wavelength of each wavelength tunable light source according to the N adjusted wavelengths common to each input / output port. Become.

  ADVANTAGE OF THE INVENTION According to this invention, when using recursive AWG as an optical switch, the multiple types of wavelength utilized as an optical signal can be set easily.

It is a block diagram showing an example of 1 composition of a wavelength tuning system of a 1st embodiment. It is a schematic diagram which shows an example of the permeation | transmission filter characteristic of NxN revolving AWG shown in FIG. It is a schematic diagram which shows an example of the power of the light output from the N * N revolving AWG shown in FIG. It is a schematic diagram which shows an example of the maximum value and minimum value of the power of the light output from the N * N revolving AWG shown in FIG. It is a schematic diagram which shows an example of a mode that leak light is output from the N * N revolving AWG shown in FIG. It is a schematic diagram which shows the example of 1 operation of an optical packet switch, and the operation example when leaked light is output from the revolving AWG.

Next, the present invention will be described with reference to the drawings.
(First embodiment)
In this embodiment, when an N × N orbiting AWG is used as an optical switch, N types of wavelengths (adjusted wavelengths) that are commonly used in each wavelength variable light source used in the N × N orbiting AWG are used. Decide each. The wavelength after adjustment is a wavelength after adjustment according to the present invention with respect to wavelengths (standard wavelengths) λ1 to λN of light used as a standard in the N × N orbiting AWG. In the wavelength adjustment system of the present embodiment, in N standard wavelengths λ1 to λN whose interval (grid interval) is X (X is a positive rational number) GHz, ± C / 2X ( The wavelength is swept within a range of (C is the speed of light), and the adjusted wavelengths of the N pieces of light that minimize the difference in power of light output from each output port are determined.

  FIG. 1 is a block diagram illustrating a configuration example of the wavelength adjustment system according to the first embodiment.

  As shown in FIG. 1, the wavelength tuning system of the present invention includes a wavelength tunable light source 10, a wavelength tuning device 20, a 1-to-N branch coupler 30, and an optical power meter 40, and an N × N revolving AWG 50 that is a measurement target is provided. The configuration is connected to the 1-to-N branch coupler 30 and the optical power meter 40.

  The N × N circulatory AWG 50 is the circulatory AWG provided with N input ports and N output ports.

  The wavelength tunable light source 10 generates light having a wavelength in the range of ± C / 2X of the standard wavelengths λ1 to λN and λ1 to λN, which is input to each input port of the N × N revolving AWG 50. The wavelength variable light source 10 changes the wavelength of the output light in accordance with, for example, a current supplied from the wavelength adjusting device 20. The wavelength tunable light source 10 can output N types of standard wavelengths λ1 to λN and light having a wavelength in the range of ± C / 2X of λ1 to λN according to the characteristics of the N × N orbiting AWG 50 to be measured. Such a configuration may be used, and a known wavelength variable light source may be used.

  The 1-to-N branch coupler 30 branches the light output from the wavelength tunable light source 10 into N branches and supplies the light to N input ports of the N × N revolving AWG 50.

  The optical power meter 40 measures the power and wavelength of light output from the N output ports of the N × N revolving AWG 50, and outputs the measurement result to the wavelength adjusting device 20.

  The wavelength adjusting device 20 includes a wavelength adjusting unit 21 that controls the wavelength of light output from the wavelength tunable light source 10 using current supplied to the wavelength tunable light source 10. The wavelength adjusting unit 21 includes a wavelength table indicating the relationship between the wavelength of light output from the wavelength tunable light source 10 and the current value supplied to the wavelength tunable light source 10. The wavelength adjusting device 20 sweeps the wavelength in the range of ± C / 2X (C is the speed of light) around the standard wavelengths λ1 to λN, and measures the light output from each output port measured by the optical power meter 40. The power is associated with the wavelength and stored in the wavelength table, for example. Then, for each of the standard wavelengths λ1 to λN, an adjusted wavelength is determined so that the difference in power of light output from the N output ports is minimized.

  The wavelength adjustment device 20 includes, for example, a known constant current circuit capable of controlling the output current, a CPU that executes processing according to a program, a program, and a memory that stores a measurement result by the wavelength table and the optical power meter. It can be realized by a circuit or a known information processing apparatus.

  FIG. 2 is a schematic diagram illustrating an example of a transmission filter characteristic of the N × N revolving AWG illustrated in FIG. 1.

  As shown in FIG. 2, the N × N orbiting AWG 50 includes N input ports and output ports whose transmission wavelength interval (grid interval) is X GHz. The grid interval and the wavelength have a relationship of wavelength = light speed C (m / s) ÷ grid interval. That is, in an N × N orbiting AWG with a grid interval of X GHz, the interval of the transmission wavelength for each output port is C ÷ X.

  At the time of wavelength adjustment, the wavelength adjustment device 20 changes the current supplied to the wavelength tunable light source 10 by the wavelength adjustment unit 21, and changes the standard wavelengths λ1 to λN for the light of the standard wavelengths λ1 to λN output from the wavelength tunable light source 10. The wavelength is swept at the center within a range of ± C / 2X (C is the speed of light). For example, when adjusting the standard wavelength λy (y = 1, 2, 3,..., N), the wavelength adjusting unit 21 refers to the wavelength table and λy−C / 2X (nm) registered in the wavelength table. To λy + C / 2X (nm), a current corresponding to each preset wavelength is sequentially supplied to the wavelength tunable light source 10, and the output wavelength of the wavelength tunable light source 10 is changed from λy−C / 2X (nm) to λy + C /. Change to 2X (nm).

  The light output from the wavelength tunable light source 10 is N-branched by the 1-to-N branch coupler 30 and is input to each input port of the N × N revolving AWG 50. The light input to the N × N revolving AWG 50 is output from an output port set for each input port according to the wavelength.

  The optical power meter 40 measures the wavelength and power of the light output from each output port of the N × N revolving AWG 50 and supplies the measurement result to the wavelength adjusting device 20.

  The wavelength adjustment device 20 stores the light power value for each output port received from the optical power meter 40 in association with the wavelength, for example, in the wavelength table. Then, a difference between the maximum value and the minimum value of the power of each wavelength set in advance from λy−C / 2X to λy + C / 2X is calculated, and the difference value is stored in association with the wavelength. Then, the wavelength at which the difference in light power from each output port is minimized is detected. This detected wavelength is an adjusted wavelength corresponding to the standard wavelength λy that is commonly set for the N variable wavelength light sources when the N × N orbiting AWG 50 to be measured is used as an optical switch. The wavelength adjusting device 20 performs these operations for N standard wavelengths λ1 to λN, respectively.

  FIG. 3 is a schematic diagram illustrating an example of the power of light output from the N × N orbiting AWG illustrated in FIG. 1. FIG. 4 is a schematic diagram illustrating an example of the maximum value and the minimum value of the power of light output from the N × N recursive AWG illustrated in FIG. 3.

  For example, in the N × N orbiting AWG 50 having wavelength recurring properties shown in FIG. 3, when light of wavelength λ1 is input to all input ports, it is input to the input port of port number 1 and the output port of port number 1 Assuming that the attenuation factor of the light of wavelength λ1 outputted from is the smallest, is inputted to the input port of port number N, and has the largest attenuation factor of the light of wavelength λ1 outputted from the output port of port number N, As shown in FIG. 3, there is a difference in the power of light output from each output port.

  As shown in FIG. 4, for example, when adjusting the standard wavelength λ1, the wavelength adjusting device 20 changes the light output from the N × N revolving AWG 50 from the wavelength λ1−C / 2x (nm) to λ1 + C / 2x (nm). ) To obtain the optical power output from the output ports of port number 1 (Out Port 1) to port number N (Out Port N). In the example shown in FIGS. 3 and 4, the attenuation rate of light output from port number 1 (Out Port 1) is the smallest, and the attenuation rate of light output from port number N (Out Port N) is the lowest. Since it is large, the wavelength λ1 + α having the smallest difference between them is detected. This wavelength λ1 + α is the adjusted wavelength corresponding to the standard wavelength λ1.

  According to the present embodiment, since only one wavelength tunable light source 10 is required, N wavelengths (adjusted wavelengths) common to each input / output port used in the N × N orbiting AWG 50 to be measured are efficiently used. Can be determined. Even when a standby wavelength tunable light source is prepared, the output wavelength of each standby wavelength tunable light source may be set in accordance with the N adjusted wavelengths common to each input / output port. Becomes easier. Furthermore, in this embodiment, since the difference in the power of the light output from each output port is suppressed to the minimum, the influence due to the difference in the dynamic range of each receiver connected to the output port can be reduced.

Therefore, when the circular AWG is used as an optical switch, a plurality of types of wavelengths used as optical signals can be set easily.
(Second Embodiment)
In the second embodiment, the power of leakage light (crosstalk) output from a port other than the intended port of the N × N recursive AWG 50 is measured, and the standard wavelengths λ1 to λN that minimize the power of the leakage light are measured. Determine the adjusted wavelength of the light.

  FIG. 5 is a schematic diagram illustrating an example of a state in which leakage light is output from the N × N orbiting AWG illustrated in FIG. 1.

  As shown in FIG. 2, in the N × N orbiting AWG 50, there is an overlapping region between adjacent wavelength bands in the transmission filter characteristics. For example, the light of the wavelength λ1-α is applied to the input port of the port number 2. When input, the light passes through a filter having a transmission wavelength of the standard wavelength λN, and is output as leakage light from the output port of port number 3. When light of wavelength λ1 + α is input to the input port of port number 2, the light passes through a filter having a transmission wavelength of standard wavelength λ2, and is output as leaked light from the output port of port number 1.

  For example, in an optical packet switch including a wavelength tunable light source, a modulator (optical modulator), an N × N revolving AWG, and a receiver, when the power of the leaked light becomes larger than a light receiving threshold in the receiver, the receiver A bit error occurs at. As shown in FIG. 6, in an N × N recursive AWG, an output port having a large light power attenuation rate between input and output ports needs to set a light reception threshold value low in the receiver. If the power (integrated value) of the leaked light is large, the possibility of a bit error occurring at the receiver increases.

  Therefore, the wavelength adjusting device 20 of the present embodiment associates the power of leakage light due to light crosstalk from the wavelength and power value of light for each output port received from the optical power meter 40, for example, Store in the wavelength table. Then, for each of the standard wavelengths λ1 to λN, a wavelength at which the power of leakage light is the smallest is detected. This detected wavelength is an adjusted wavelength corresponding to the standard wavelengths λ1 to λN that is commonly used by the N variable wavelength light sources when the N × N revolving AWG 50 to be measured is used as an optical switch.

  In the wavelength tuning system of the present embodiment, the output of the wavelength tunable light source 10 is sequentially connected to each input port of the N × N revolving AWG 50, and ± C / 2X (C around the standard wavelengths λ1 to λN for each input port. The optical power meter 40 measures the power (integrated value) of the leaked light at each output port and outputs the measured value to the wavelength adjusting device 20. That is, in the wavelength adjustment system of this embodiment, the 1-to-N branch coupler 30 is not necessary. Other configurations and operations are the same as those of the wavelength adjustment system of the first embodiment.

  According to the present embodiment, since only one wavelength tunable light source 10 is required, N wavelengths (adjusted wavelengths) common to each input / output port used in the N × N orbiting AWG 50 to be measured are efficiently used. Can be determined. In addition, even when a standby wavelength tunable light source is prepared, it is only necessary to set the transmission wavelength of each backup wavelength tunable light source according to the N adjusted wavelengths common to each input / output port. It becomes easy. Furthermore, in this embodiment, since the power of leakage light due to crosstalk of light output from each output port is suppressed to the minimum, it is possible to reduce the influence due to the difference in the dynamic range of each receiver connected to the output port. .

  Therefore, as in the first embodiment, when the circular AWG is used as an optical switch, a plurality of types of wavelengths used as optical signals can be easily set.

DESCRIPTION OF SYMBOLS 10 Wavelength variable light source 20 Wavelength adjustment apparatus 21 Wavelength adjustment part 30 1 to N branch coupler 40 Optical power meter 50 NxN revolving AWG

Claims (8)

When N is a positive integer,
Wavelength adjustment for determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, used in an arrayed waveguide diffraction grating having wavelength recurring characteristics, including N input ports and output ports A system,
A wavelength tunable light source capable of changing the wavelength from the outside and outputting light of the N types of wavelengths;
A 1-to-N branch coupler for branching light output from the wavelength tunable light source into N branches and supplying the light to the input ports of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
The wavelength and power values of light measured by the optical power meter are received, and the light of the N types of standard wavelengths that minimizes the difference in power of light output from the output port of the arrayed waveguide grating is obtained. A wavelength adjusting device for determining a corresponding adjusted wavelength, and
A wavelength adjustment system having: When the standard wavelength interval is X GHz and the speed of light is C,
The wavelength adjusting device is:
For each standard wavelength, the wavelength of light output from the wavelength tunable light source is changed within a range of ± C / 2X, and the maximum and minimum values of the power of light output from the output port of the arrayed waveguide grating The wavelength adjustment system according to claim 1, wherein a difference in values is measured for each wavelength, and a wavelength that minimizes the difference is determined as the adjusted wavelength. When N is a positive integer,
Wavelength adjustment for determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, used in an arrayed waveguide diffraction grating having wavelength recurring characteristics, including N input ports and output ports A system,
A wavelength tunable light source that can change the wavelength from the outside and supplies the light of the N types of wavelengths to the input port of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
The light wavelength and power values measured by the optical power meter are received, and the power of light leaking from an unintended output port that does not correspond to the standard wavelength among the output ports of the arrayed waveguide grating is minimized. , A wavelength adjustment device that determines an adjusted wavelength corresponding to each of the N types of standard wavelengths, and
A wavelength adjustment system having: When the standard wavelength interval is X GHz and the speed of light is C,
The wavelength adjusting device is:
Intention to be measured by the optical power meter among the output ports of the arrayed waveguide grating by changing the wavelength of light output from the wavelength variable light source in a range of ± C / 2X with respect to the standard wavelength. 4. The wavelength adjustment system according to claim 3, wherein an integrated amount of light leaking from an output port that is not received is received, and a wavelength that minimizes the integrated amount is determined as the adjusted wavelength. When N is a positive integer,
For determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, which is used in an arrayed waveguide grating having a wavelength circulation property, which has N input ports and output ports. A wavelength adjustment method,
A wavelength tunable light source capable of changing the wavelength from the outside and outputting light of the N types of wavelengths;
A 1-to-N branch coupler for branching light output from the wavelength tunable light source into N branches and supplying the light to the input ports of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
With
Receiving the wavelength and power values of the light measured by the optical power meter;
A wavelength adjustment method for respectively determining adjusted wavelengths corresponding to the N kinds of standard wavelengths of light, wherein a difference in power of light output from an output port of the arrayed waveguide grating is minimized. When the standard wavelength interval is X GHz and the speed of light is C,
For each standard wavelength, the wavelength of light output from the wavelength tunable light source is changed within a range of ± C / 2X, and the maximum and minimum values of the power of light output from the output port of the arrayed waveguide grating The wavelength adjustment method according to claim 5, wherein a difference in values is measured for each wavelength, and a wavelength that minimizes the difference is determined as the adjusted wavelength. When N is a positive integer,
For determining an adjusted wavelength, which is an adjusted wavelength corresponding to light of N types of standard wavelengths, which is used in an arrayed waveguide grating having a wavelength circulation property, which has N input ports and output ports. A wavelength adjustment method,
A wavelength tunable light source that can change the wavelength from the outside and supplies the light of the N types of wavelengths to the input port of the arrayed waveguide grating,
An optical power meter that measures the wavelength and power of light output from the output port of the arrayed waveguide grating; and
With
Receiving the wavelength and power values of the light measured by the optical power meter;
Of the output ports of the arrayed waveguide grating, the adjusted wavelengths corresponding to the light of the N types of standard wavelengths are determined so that the power of light leaking from an unintended output port that does not correspond to the standard wavelength is minimized. Wavelength adjustment method. When the standard wavelength interval is X GHz and the speed of light is C,
Intention to be measured by the optical power meter among the output ports of the arrayed waveguide grating by changing the wavelength of light output from the wavelength variable light source in a range of ± C / 2X with respect to the standard wavelength. The wavelength adjustment method according to claim 7, wherein an integrated amount of light leaking from an output port that is not received is received, and a wavelength that minimizes the integrated amount is determined as the adjusted wavelength.

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