JP5387243B2 - Optical wavelength control device and optical wavelength control method - Google Patents

Description

  The present invention relates to an optical wavelength control device and an optical wavelength control method.

  In recent years, the capacity of optical communication lines for transmitting optical signals has been increasing. Along with this, an increase in the bit rate is being promoted also in an optical transmission device that outputs an optical signal to an optical communication line.

  A digital coherent method in which an optical transmission device digitally modulates an optical signal using a heterodyne detection method or a homodyne detection method in order to transmit an optical signal at a very high bit rate (for example, 100 gigabit / second). Is newly considered.

  A receiver that receives an optical signal transmitted by the digital coherent method is provided with a local oscillation laser that outputs local oscillation light. However, in the digital coherent method, when the wavelength difference between the local oscillation light output from the local oscillation laser in the receiver and the signal light is not less than a predetermined value (for example, ± 10 picometers), the receiver appropriately transmits the optical signal. There is a problem that it becomes impossible to process. In this case, there is also a problem that the processing load on the receiver becomes large.

  Therefore, a technique for controlling the frequency of an optical signal with high accuracy has been considered (for example, see Patent Document 1).

  In the technique disclosed in Patent Document 1, the light output from the reference light source and the light output from the variable light source are directed in the same direction to the same Fabry-Perot etalon resonator (hereinafter referred to as “etalon resonator”). The filter characteristic is adjusted with reference to the light output from the reference light source, and the frequency of the light output from the variable light source is obtained with the filter characteristic as a reference.

Japanese Patent Laid-Open No. 02-307027

  However, in the technique disclosed in Patent Document 1, in order to avoid interference between lights output from two light sources, it is necessary to set the distance between the light sources so as not to cause interference. Therefore, the size of the etalon resonator becomes large, and accordingly, the size of the device including the etalon resonator becomes large.

  In addition, since the size of the etalon resonator is increased, it is difficult to keep the etalon resonators that are the conditions of the highly accurate etalon resonator in parallel.

  In addition, since the size of the etalon resonator is increased, it is difficult to control the transmission characteristics of the etalon resonator with high accuracy.

  An object of this invention is to provide the optical wavelength control apparatus and optical wavelength control method which solve the subject mentioned above.

  In order to solve the above problems, an optical wavelength control device of the present invention transmits a first resonator that transmits input signal light and local oscillation light that is input from a direction orthogonal to the direction in which the signal light is input. Based on a variable filter having the same bulk as the second resonator, a relative value between the first reference intensity and the intensity of the signal light transmitted through the first resonator, and the transmission characteristics of the first resonator A filter adjustment unit that generates a filter adjustment signal for adjusting a transmission characteristic of the first resonator, a relative value between a second reference intensity and the intensity of the local oscillation light transmitted through the second resonator, and the first An external adjustment unit for generating and outputting an external control signal for adjusting the wavelength of the local oscillation light based on the transmission characteristics of the two resonators, and the first resonator according to the filter adjustment signal. Transmission characteristics and the second resonator And a changing unit for changing the transmission characteristics.

  In order to solve the above-described problem, an optical wavelength control method of the present invention is an optical wavelength control method in an optical wavelength control device that controls the wavelength of input local oscillation light, and the optical wavelength control device includes the optical wavelength control method. Transmission characteristics of the first resonator that transmits the signal light input from the direction orthogonal to the input direction of the local oscillation light included in the variable filter, the first reference intensity, and the signal light transmitted through the first resonator Filter adjustment processing for generating a filter adjustment signal for adjusting the transmission characteristics of the first resonator based on the relative value to the intensity, and the same bulk as the first resonator for transmitting the local oscillation light To adjust the wavelength of the local oscillation light based on the transmission characteristics of the second resonator constituted by the above and the relative value between the second reference intensity and the intensity of the local oscillation light transmitted through the second resonator. Generate external control signal for outside An external adjustment processing to be output to, in response to said filter adjustment signal, and a changing process for changing the transmission characteristics and transmission characteristics of the second resonator of the first resonator.

  According to the present invention, the relative value of the local light emission wavelength with respect to the signal light wavelength can be stably controlled without increasing the size of the apparatus.

It is a figure which shows the structure of the optical wavelength control apparatus according to Embodiment 1 of this invention. FIG. 2 is an oblique projection view of the variable filter shown in FIG. 1. It is a figure which shows an example of the operation | movement which calculates the relative value of the wavelength of signal light based on the relative value of the transmission characteristic of a 1st resonator, and the intensity | strength of signal light. It is a figure which shows an example of the operation | movement which calculates the relative value of the wavelength of local oscillation light based on the relative value of the transmission characteristic of a 2nd resonator, and the intensity | strength of local oscillation light. It is a figure which shows the structure of the optical wavelength control apparatus of Embodiment 2. FIG.

(Embodiment 1)
Hereinafter, an optical wavelength control device (including an optical wavelength control method) according to Embodiment 1 of the present invention will be described.

  As shown in FIG. 1, the optical wavelength control device 1 according to the first embodiment includes optical transmission cables 101 and 102, a variable filter 11, a changing unit 113, beam splitters 121 and 122, and optical monitors 131 to 134. , A calculation unit 141, an external adjustment unit 142, and a filter adjustment unit 15 are provided. In addition, a photodiode is mentioned as an example of the optical monitors 131-134.

  In the present embodiment, a case where an etalon resonator using an interference phenomenon of light that is multiple-reflected between reflecting mirrors arranged opposite to each other with a medium interposed therebetween will be described as an example.

  FIG. 2 is an oblique projection of the variable filter 11 shown in FIG.

  As shown in FIG. 2, the variable filter 11 shown in FIG. 1 functions as the first resonator 111 that transmits the signal light SG1, and also functions as the second resonator 112 that transmits the local oscillation light SG2.

  The first resonator 111 and the second resonator 112 are configured by “the same bulk”, the direction in which the first resonator 111 transmits the signal light SG1, and the second resonator 112 is locally oscillated. It arrange | positions so that the direction which permeate | transmits light SG2 may be orthogonal.

  When the variable filter 11 is configured by a bulk formed in a hexahedron (cubic or rectangular parallelepiped) shape, the first resonator 111 has two opposite faces among the six faces of the hexahedron (in the example of FIG. 2). , Surfaces SF11, SF12). Further, the second resonator 112 is configured by two opposing surfaces (surfaces SF21 and SF22 in the example of FIG. 2) other than the two opposing surfaces (surfaces SF11 and SF12) constituting the first resonator 111. The

  The first resonator 111 transmits the input signal light SG <b> 1 with a transmittance described later and outputs the signal light SG <b> 1 to the optical monitor 131.

  As shown in FIG. 3, the transmittance of the first resonator 111 shows a periodic transmission characteristic with respect to the wavelength of the signal light SG <b> 1 input to the first resonator 111.

  Further, the second resonator 112 transmits the input local oscillation light SG <b> 2 with a transmittance described later and outputs it to the optical monitor 132.

  As shown in FIG. 4, the transmittance of the second resonator 112 exhibits a periodic transmission characteristic with respect to the wavelength of the local oscillation light SG <b> 2 input to the second resonator 112.

  In addition, the 1st resonator 111 and the 2nd resonator 112 are comprised by the same bulk. Therefore, the relative relationship between the transmission characteristics of the first resonator 111 and the transmission characteristics of the second resonator 112 is kept constant.

  Specifically, when the transmittance of the first resonator 111 increases, the transmittance of the second resonator 112 also increases.

  Further, when the transmittance of the first resonator 111 is decreased, the transmittance of the second resonator 112 is also decreased.

  The changing unit 113 changes the transmittance of the first resonator 111 and the transmittance of the second resonator 112 based on the “filter adjustment signal” output from the filter adjusting unit 15.

  When changing each transmittance of the first resonator 111 and the second resonator 112 by bulk temperature tuning, a temperature control element such as a Peltier element is used as the changing unit 113.

  The “filter adjustment signal” refers to a signal for adjusting the transmittance of the first resonator 111 and the transmittance of the second resonator 112.

  The beam splitter 121 shown in FIG. 1 branches and outputs the signal light SG1 output from the optical tap 21 and transmitted by the optical transmission cable 101 to the first resonator 111 and the optical monitor 133.

  The optical transmission cable 101 transmits the signal light SG1 in a predetermined direction. The optical transmission cable 102 transmits the local oscillation light SG2 on the optical transmission cable 101 in a direction orthogonal to a predetermined direction in which the signal light SG1 is transmitted.

  The optical monitor 131 is a “first optical monitor” that detects the intensity of the signal light SG <b> 1 that has passed through the first resonator 111 and outputs the detected intensity to the calculation unit 141.

The optical monitor 133 is a “third optical monitor” that detects the intensity of the signal light SG1 as “first reference intensity I _STD1 ”. The optical monitor 133 outputs the detected first reference intensity I _STD1 to the calculation unit 141.

The calculation unit 141 calculates the relative value of the intensity output from the optical monitor 131 with respect to the first reference intensity I _STD1 output from the optical monitor 133 for each predetermined period.

  That is, in the present embodiment, the calculation unit 141 calculates the relative value of the intensity of the signal light SG1 that has passed through the first resonator 111 with respect to the intensity of the signal light SG1.

  Specifically, the calculation unit 141 calculates the ratio of the intensity of the signal light SG1 transmitted through the first resonator 111 to the intensity of the signal light SG1 (that is, the transmittance of the first resonator 111), and the intensity of the signal light SG1. Is calculated as a relative value.

  Then, the calculation unit 141 outputs the calculated relative value of the intensity of the signal light SG1 to the filter adjustment unit 15.

  The filter adjustment unit 15 serves to adjust the transmission characteristics of the first resonator 111 and the transmission characteristics of the second resonator 112 with reference to the relative value of the intensity of the signal light SG1. The filter adjustment unit 15 generates a filter adjustment signal for adjusting these transmission characteristics and outputs the filter adjustment signal to the change unit 113.

  In the present embodiment, the filter adjustment unit 15 stores in advance a “first reference relative value” that is a reference value of the relative value of the intensity of the signal light SG1.

  Then, the filter adjustment unit 15 compares the relative value of the intensity of the signal light SG1 output from the calculation unit 141 with the first reference relative value.

In the example shown in FIG. 3, the first reference relative value stored in the filter adjustment unit 15 is “I ₁₁ / I _STD1 ”, and the relative value of the intensity of the signal light SG1 output from the calculation unit 141 is Consider the case of “I ₁₂ / I _STD1 ”. In this case, the wavelength lambda ₁₂ of the signal light SG1 intensity I ₁₂ of optical monitor 131 is detected, that is deviated by the wavelength difference DF ₁ from the wavelength lambda ₁₁ of the signal light SG1 corresponding to the first reference relative value Equivalent to.

Therefore, if the comparison result shows that the first reference relative value “I ₁₁ / I _STD1 ” and the relative value “I ₁₂ / I _STD1 ” of the signal light SG 1 are different, A filter adjustment signal is generated and changed so that the relative value becomes the same as the relative value of the intensity of the signal light SG1, that is, cancels the change of the relative value of the intensity of the signal light SG1 with respect to the first reference relative value. Output to the unit 113.

  In the present embodiment, each of the wavelength of the signal light SG1 and the wavelength of the local oscillation light SG2 is controlled with a certain accuracy. Therefore, one specific peak (for example, point P2) in the transmission characteristics shown in FIG. 3 and one of the two minimum points (valleys) of transmittance existing across the specific peak (for example, point P1) ), The transmittance of the first resonator 111 can be controlled.

  In addition, as one form of the structure of the control mechanism for changing the transmittance of the first resonator 111, the filter adjustment unit 15 is configured by a temperature adjustment circuit, and on the temperature adjustment element provided as the change unit 113. A bulk in which the first resonator 111 and the second resonator 112 are formed is mounted.

  The filter adjustment unit 15 (temperature adjustment circuit) generates a filter adjustment signal for adjusting the transmittance of the first resonator 111 and outputs the filter adjustment signal to the change unit 113.

  Then, the change part 113 (temperature control element) changes the transmittance | permeability of the 1st resonator 111 by performing bulk temperature tuning according to a filter adjustment signal. Thereby, even when the wavelength of the signal light SG1 is deviated from the wavelength of the signal light SG1 corresponding to the first reference relative value, the transmission characteristics of the first resonator 111 can be made to follow according to the deviation of the wavelength. It becomes possible.

  In addition, the 1st resonator 111 and the 2nd resonator 112 are comprised by the same bulk. Therefore, when the filter adjustment unit 15 changes the transmittance of the first resonator 111, the transmittance of the second resonator 112 also changes while maintaining a certain relative relationship with the transmittance of the first resonator 111.

  The beam splitter 122 branches the local oscillation light SG2 output from the optical tap 23 and transmitted by the optical transmission cable 102 to the second resonator 112 and the optical monitor 134 and outputs the branched light.

  The optical monitor 132 is a “second optical monitor” that detects the intensity of the local oscillation light SG 2 that has passed through the second resonator 112 and outputs the detected intensity to the external adjustment unit 142.

The optical monitor 134 is a “fourth optical monitor” that detects the intensity of the local oscillation light SG2 as the second reference intensity I _STD2 . The optical monitor 134 outputs the detected second reference intensity I _STD2 to the external adjustment unit 142.

  The external adjustment unit 142 generates an “external control signal” based on the relative value of the intensity of the local oscillation light SG2 and the “transmission characteristic of the second resonator 112 with respect to the local oscillation light SG2”, and sends it to the laser wavelength adjustment device 24. Output.

  The “external control signal” is a signal for adjusting the wavelength of the local oscillation light SG2 output from the wavelength tunable laser 22.

In the present embodiment, the external adjustment unit 142 calculates the relative value of the intensity output from the optical monitor 132 with respect to the second reference intensity I _STD2 output from the optical monitor 134.

  That is, in the present embodiment, the external adjustment unit 142 calculates a relative value of the intensity of the local oscillation light SG2 that has passed through the second resonator 112 with respect to the intensity of the local oscillation light SG2.

  Specifically, the external adjustment unit 142 determines the ratio of the intensity of the local oscillation light SG2 transmitted through the second resonator 112 to the intensity of the local oscillation light SG2 (that is, the transmittance of the second resonator 112). Calculated as a relative value of the intensity of the light SG2.

  The external adjustment unit 142 stores in advance a “second reference relative value” that is a reference value of the relative value of the intensity of the local oscillation light SG2.

  Then, the external adjustment unit 142 compares the relative value of the intensity of the local oscillation light SG2 calculated by the external adjustment unit 142 with the second reference relative value.

In the example shown in FIG. 4, the second reference relative value stored in the external adjustment unit 142 is “I ₂₁ / I _STD2 ”, and the relative value of the intensity of the local oscillation light SG2 calculated by the external adjustment unit 142 is Consider the case of “I ₂₂ / I _STD2 ”. In this case, the wavelength lambda ₂₂ of the local oscillator light SG2 intensity I ₂₂ of optical monitor 132 has detected is deviated by the wavelength difference DF ₂ from the wavelength lambda ₂₁ of the local oscillator light SG2 corresponding to the second reference relative value It corresponds to that.

Therefore, the external adjustment unit 142 performs external control so that the second reference relative value “I ₂₁ / I _STD2 ” and the relative value “I ₂₂ / I _STD2 ” of the intensity of the local oscillation light SG2 calculated by itself are the same. A signal is generated and output to the laser wavelength adjusting device 24.

  Then, the laser wavelength adjustment device 24 adjusts the wavelength of the local oscillation light SG2 output from the wavelength tunable laser 22 in accordance with the external control signal output from the external adjustment unit 142.

  In the present embodiment, the first resonator 111 and the second resonator 112 are configured in the same bulk, and the first resonator 111 and the first resonator 111 are connected by a common filter adjustment unit 15 (for example, the same temperature control mechanism). Each transmittance of the second resonator 112 is controlled. Therefore, the transmission characteristic of the first resonator 111 and the transmission characteristic of the second resonator 112 change while maintaining a certain relative relationship, and accordingly, the wavelength of the signal light SG1 transmitted through the first resonator 111, The relative value with respect to the wavelength of the local oscillation light SG2 transmitted through the second resonator 112 maintains a constant value.

  Note that by setting arbitrary values as the first reference relative value and the second reference relative value, it is possible to cause the optical wavelength control device 1 to perform various controls on the wavelength of the local oscillation light SG2.

  For example, by setting the first reference relative value and the second reference relative value to the same value, the relative value of the wavelength of the local oscillation light SG2 with respect to the wavelength of the signal light SG1 becomes zero, that is, the local oscillation light You may control so that the wavelength of SG2 may become the same wavelength as the wavelength of signal light SG1.

  In this case, the optical wavelength control device 1 controls the wavelength tunable laser 22 so as to output the local oscillation light SG2 having the same frequency as the frequency of the signal light SG1 input to the optical wavelength control device 1. Therefore, the optical wavelength control device 1 can be operated so as to perform the wavelength control of the homodyne detection method.

  Further, by setting the first reference relative value and the second reference relative value to be different from each other, the relative value of the wavelength of the local oscillation light SG2 with respect to the wavelength of the signal light SG1 is a constant value other than zero (for example, ± 10 You may control so that it may become a picometer.

  In this case, the optical wavelength control device 1 controls the wavelength tunable laser 22 so as to output the local oscillation light SG2 having a frequency (for example, an intermediate frequency) different from the frequency of the signal light SG1 input to the optical wavelength control device 1. Will be. Therefore, the optical wavelength control device 1 can be operated so as to perform the wavelength control of the heterodyne detection method.

  As described above, according to the first embodiment of the present invention, the relative value of the wavelength of the local oscillation light SG2 with respect to the wavelength of the signal light SG1 can be stably controlled.

  That is, the optical wavelength control device 1 can stably control the wavelength of the local oscillation light SG2 and the wavelength of the signal light SG1 to the same wavelength, and the wavelength of the signal light SG1 and the wavelength of the local oscillation light SG2 It becomes possible to stably control the wavelength difference between them to be an arbitrary fixed value.

  Further, according to the first embodiment, two resonators (the first resonator 111 and the second resonator 112) are formed in the same bulk constituting the variable filter 11.

Thereby, the structure of the optical wavelength control apparatus 1 becomes a very simple structure, and it can suppress that the size of the optical wavelength control apparatus 1 becomes large.
(Embodiment 2)
Next, the optical wavelength control device of Embodiment 2 will be described.

  The optical wavelength control device 1A according to the second embodiment is different in that it includes the modulation signal output unit 16 and the addition unit 17 illustrated in FIG. 5 and does not include the beam splitters 121 and 122 and the optical monitors 133 and 134. 1 is different from the optical wavelength control device 1 shown in FIG.

In the second embodiment, when calculating the relative value of the intensity of the signal light SG1, the calculation unit 141 detects a peak in the transmission characteristics of the first resonator 111 (the maximum value of the transmittance of the signal light SG1). . The calculating unit 141 uses the intensity of the signal light SG1 transmitted through the first resonator 111 at the peak as the first reference intensity I _STD1 .

In the second embodiment, when calculating the relative value of the intensity of the local oscillation light SG2, the external adjustment unit 142 detects the transmittance peak in the transmission characteristics of the second resonator 112. Then, the intensity of the local oscillation light SG2 transmitted through the second resonator 112 at the peak is used as the second reference intensity I _STD2 . Hereinafter, a case where the transmission characteristics of the first resonator 111 and the transmission characteristics of the second resonator 112 are the same will be described as an example.

  The modulation signal output unit 16 generates and outputs a “modulation signal” at a predetermined period. Here, the “modulation signal” refers to a signal that changes the transmittance of the first resonator 111 by a predetermined value.

  In the present embodiment, the modulation signal output unit 16 stores in advance a predetermined modulation level for changing the transmittance of the first resonator 111 by a predetermined value. Then, when outputting the modulation signal, the modulation signal output unit 16 generates and outputs a modulation signal obtained by adding the modulation signal output immediately before and the modulation level.

  When the changing unit 113 is a temperature control element (for example, a Peltier element), the modulation level changes the temperature of the bulk in which the temperature control element forms the first resonator 111 and the second resonator 112 by a predetermined temperature. Signal level.

  The addition unit 17 adds the filter adjustment signal output from the filter adjustment unit 15 and the modulation signal output from the modulation signal output unit 16 and outputs the result to the change unit 113.

  Then, the changing unit 113 changes the transmittance of the first resonator 111 according to the added filter adjustment signal and modulation signal. When the filter adjusting unit 15 changes the transmittance of the first resonator 111, the transmittance of the second resonator 112 formed in the same bulk as the first resonator 111 is also changed. It changes while maintaining a certain relative relationship with the transmittance of the vessel 111.

  Next, an operation in which the calculation unit 141 according to the second embodiment detects a peak in the transmission characteristics of the first resonator 111 (the maximum value of the transmittance of the first resonator 111 with respect to the signal light SG1) will be described.

  First, while the modulation signal output unit 16 is not outputting the modulation signal, the filter adjustment unit 15 outputs the filter adjustment signal to the addition unit 17. Then, the adding unit 17 outputs this filter adjustment signal to the changing unit 113.

  Thereafter, the optical monitor 131 outputs the intensity of the signal light SG1 transmitted through the first resonator 111 controlled by the filter adjustment signal to the calculation unit 141. The calculation unit 141 stores the intensity output from the optical monitor 131.

  Thereafter, the modulation signal output unit 16 generates a modulation signal and outputs the modulation signal to the addition unit 17. Then, the adding unit 17 adds the modulated signal and the filter adjustment signal output from the filter adjusting unit 15 and outputs the result to the changing unit 113.

  Then, the changing unit 113 changes the transmittance of the first resonator 111 according to the added filter adjustment signal and modulation signal.

  Then, the optical monitor 131 detects the intensity of the signal light SG1 that has passed through the first resonator 111 whose transmittance has been changed by the modulation signal, and outputs the detected intensity to the calculating unit 141.

  Then, the calculation unit 141 calculates a relative value (for example, a subtraction value) between the intensity stored in the calculation unit 141 and the intensity output from the optical monitor 131. In this case, the calculation unit 141 detects a differential value of the transmittance of the signal light SG1 in the transmission characteristics of the first resonator 111.

  Then, the filter adjustment unit 15 adjusts the first resonator 111 so that the differential value detected by the calculation unit 141 is zero, that is, the tangential slope of the transmission characteristic of the first resonator 111 is zero. Control the transmittance. Thereby, the optical monitor 131 can detect the maximum value of the transmittance of the first resonator 111 with respect to the signal light SG1.

Thereafter, the calculation unit 141 uses, as the first reference intensity I _STD1 , the relative value of the intensity of the signal light SG1 by using the intensity of the signal light SG1 transmitted through the first resonator 111 when the transmittance reaches the maximum value. Is calculated.

  Then, the filter adjustment unit 15 compares the relative value of the intensity of the signal light SG1 output from the calculation unit 141 with the first reference relative value, and if they are different as a result of the comparison, the signal light SG1 A filter adjustment signal is generated so that the relative value of the intensity and the first reference relative value are the same, and output to the adding unit 17.

  The optical monitor 132 detects the intensity of the local oscillation light SG2 that has passed through the second resonator 112 controlled by the filter adjustment signal, and outputs the detected intensity to the external adjustment unit 142. The external adjustment unit 142 stores the intensity output from the optical monitor 132.

  Thereafter, the changing unit 113 changes the transmittance of the second resonator 112 according to a signal obtained by adding the modulation signal output from the modulation signal output unit 16 and the filter adjustment signal output from the filter adjustment unit 15. To do.

  Subsequently, the optical monitor 132 outputs the intensity of the local oscillation light SG2 transmitted through the second resonator 112 whose transmittance has been changed by the modulation signal to the external adjustment unit 142.

  Then, the external adjustment unit 142 calculates a relative value (for example, a subtraction value) between the intensity stored by itself and the intensity output from the optical monitor 132. In this case, the external adjustment unit 142 detects the differential value of the transmittance of the local oscillation light SG2 in the transmission characteristics of the second resonator 112.

Then, the external adjustment unit 142 determines the intensity output from the optical monitor 132 when the differential value (the slope of the tangent in the transmission characteristics of the second resonator 112) detected by itself is zero, as the second reference intensity. I _STD2 is used to calculate the relative value of the intensity of the local oscillation light SG2.

  The operation in which the external adjustment unit 142 according to the second embodiment generates the external control signal based on the relative value of the intensity of the local oscillation light SG2 and the transmission characteristic of the second resonator 112 is the same as the operation in the first embodiment. is there.

As described above, according to the second embodiment, when calculating the relative value of the wavelength of the signal light SG1, the calculation unit 141 detects a peak in the transmission characteristics of the first resonator 111. Therefore, it is not necessary to provide an optical monitor 133 that detects the intensity of light not transmitted through the first resonator 111 as the first reference intensity I _STD1 .

Further, according to the second embodiment, when calculating the relative value of the wavelength of the local oscillation light SG2, the external adjustment unit 142 detects a peak in the transmission characteristics of the second resonator 112. Therefore, it is not necessary to provide an optical monitor 134 for detecting the intensity of light that has not passed through the second resonator 112 as the second reference intensity I _STD2 .

  Thereby, the configuration of the optical wavelength control device can be further simplified as compared with the first embodiment. Therefore, it can suppress that the size of the optical wavelength control apparatus becomes large.

  The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A Optical wavelength control apparatus 101,102 Optical transmission cable 11 Variable filter 111 1st resonator 112 2nd resonator 113 Change part 121,122 Beam splitter 131,132,133,134 Optical monitor 141 Calculation part 142 External adjustment part DESCRIPTION OF SYMBOLS 15 Filter adjustment part 16 Modulation signal output part 17 Addition part 21, 23 Optical tap 22 Wavelength variable laser 24 Laser wavelength adjustment apparatus

Claims (9)

A variable filter in which a first resonator that transmits input signal light and a second resonator that transmits local oscillation light that is input from a direction orthogonal to the direction in which the signal light is input are configured in the same bulk;
A filter adjustment signal for adjusting the transmission characteristic of the first resonator based on the relative value of the first reference intensity and the intensity of the signal light transmitted through the first resonator and the transmission characteristic of the first resonator. A filter adjustment unit for generating
Based on the relative value of the second reference intensity and the intensity of the local oscillation light transmitted through the second resonator and the transmission characteristic of the second resonator, an external control signal for adjusting the wavelength of the local oscillation light is obtained. An external adjustment unit that generates and outputs to the outside;
An optical wavelength control apparatus comprising: a changing unit that changes transmission characteristics of the first resonator and transmission characteristics of the second resonator in accordance with the filter adjustment signal. In the optical wavelength control device according to claim 1,
A first optical monitor for detecting the intensity of the signal light transmitted through the first resonator;
A second optical monitor for detecting the intensity of the local oscillation light transmitted through the second resonator;
A calculation unit that calculates a relative value between the first reference intensity and the intensity detected by the first light monitor;
The filter adjustment unit generates, as the filter adjustment signal, a signal for controlling the first resonator so that the relative value calculated by the calculation unit becomes a first reference relative value,
The external adjustment unit outputs, as the external control signal, a signal such that a relative value between the second reference intensity and the intensity detected by the second light monitor becomes a second reference relative value. Wavelength control device. In the optical wavelength control device according to claim 2,
A third light monitor that detects the intensity of the signal light as the first reference intensity;
A fourth optical monitor that detects the intensity of the local oscillation light as the second reference intensity;
The calculating unit calculates a relative value between the intensity detected by the first light monitor and the first reference intensity detected by the third light monitor;
The filter adjustment unit generates, as the filter adjustment signal, a signal for controlling the first resonator so that the relative value calculated by the calculation unit becomes the first reference relative value.
The external adjustment unit outputs a signal such that a relative value between the intensity detected by the second light monitor and the second reference intensity detected by the fourth light monitor becomes the second reference relative value. Output as a light wavelength control device. In the optical wavelength control device according to claim 2,
A modulation signal output unit for generating a modulation signal for changing the transmission characteristics of the first resonator;
An addition unit that adds the filter adjustment signal output from the filter adjustment unit and the modulation signal generated by the modulation signal output unit to the change unit;
The calculation unit detects, as the first reference intensity, the intensity of the signal light transmitted through the first resonator at the transmission characteristic peak of the first resonator, and detects the detected first reference intensity and the first light. Calculate the relative value with the intensity detected by the monitor,
The external adjustment unit detects the intensity of the local oscillation light transmitted through the second resonator at the peak of the transmission characteristic of the second resonator as the second reference intensity, and the detected second reference intensity and the first Based on the relative value of the intensity detected by the two-light monitor and the transmission characteristics of the second resonator, the external control signal is generated,
The changing unit changes the transmission characteristics of the first resonator and the second resonator based on the added filter adjustment signal and modulation signal. In the optical wavelength control device according to any one of claims 1 to 4,
The variable filter is formed so as to have a hexahedral shape, and the first resonator is configured by two opposing surfaces among the six surfaces of the hexahedron, and the second resonator is configured as described above. An optical wavelength control device comprising two opposing surfaces other than the two surfaces constituting the first resonator. An optical wavelength control method in an optical wavelength control device for controlling the wavelength of input local oscillation light,
Transmission characteristics of a first resonator that transmits signal light input from a direction orthogonal to the direction of input of the local oscillation light included in the variable filter included in the optical wavelength control device, the first reference intensity, and the first A filter adjustment process for generating a filter adjustment signal for adjusting the transmission characteristics of the first resonator based on the relative value of the intensity of the signal light transmitted through the resonator;
Relative transmission characteristics of the second resonator composed of the same bulk as the first resonator that transmits the local oscillation light, the second reference intensity, and the intensity of the local oscillation light transmitted through the second resonator An external adjustment process for generating an external control signal for adjusting the wavelength of the local oscillation light based on the value and outputting the external control signal to the outside;
An optical wavelength control method comprising: changing processing for changing transmission characteristics of the first resonator and transmission characteristics of the second resonator according to the filter adjustment signal. In the optical wavelength control method according to claim 6,
A process of detecting the intensity of the signal light transmitted through the first resonator with a first optical monitor provided in the optical wavelength control device;
A process of detecting the intensity of the local oscillation light transmitted through the second resonator with a second optical monitor provided in the optical wavelength control device;
A calculation process for calculating a relative value between the first reference intensity and the intensity detected by the first light monitor;
In the filter adjustment process, a signal for controlling the first resonator is generated as the filter adjustment signal so that the relative value calculated in the calculation process becomes a first reference relative value,
In the external adjustment process, a signal that outputs a relative value between the second reference intensity and the intensity detected by the second light monitor as a second reference relative value is output as the external control signal. Wavelength control method. In the optical wavelength control method according to claim 7,
A process of detecting the intensity of the signal light with the third optical monitor included in the optical wavelength control device as the first reference intensity;
A process of detecting the intensity of the local oscillation light with the fourth optical monitor included in the optical wavelength control device as the second reference intensity,
In the calculation process, a relative value between the intensity detected by the first light monitor and the first reference intensity detected by the third light monitor is calculated,
In the filter adjustment process, a signal for controlling the first resonator is generated as the filter adjustment signal so that the relative value calculated in the calculation process becomes the first reference relative value.
In the external adjustment process, a signal such that a relative value between the intensity detected by the second light monitor and the second reference intensity detected by the fourth light monitor becomes the second reference relative value is used as the external control signal. The optical wavelength control method characterized by outputting as follows. In the optical wavelength control method according to claim 7,
Modulation signal output processing for generating a modulation signal for changing the transmission characteristics of the first resonator;
An addition process for adding the filter adjustment signal output in the filter adjustment process and the modulation signal generated in the modulation signal output process;
In the calculation process, the intensity of the signal light transmitted through the first resonator at the peak of the transmission characteristic of the first resonator is detected as the first reference intensity, and the detected first reference intensity and the first light are detected. Calculate the relative value with the intensity detected by the monitor,
In the external adjustment process, the intensity of the local oscillation light transmitted through the second resonator at the peak of the transmission characteristic of the second resonator is detected as the second reference intensity, and the detected second reference intensity and the first Based on the relative value of the intensity detected by the two-light monitor and the transmission characteristics of the second resonator, the external control signal is generated,
The optical wavelength control method characterized in that, in the changing process, transmission characteristics of the first resonator and the second resonator are changed based on the added filter adjustment signal and modulation signal.

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