JP2002286965A - Wavelength stabilizing module and device for generating stable wavelength laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength stabilizing module that suppresses light returning from FBG to a laser light source. SOLUTION: The module is equipped with a first optical coupler 121 which branches an input signal into the principal signal and a monitor signal and which has, as a first prescribed ratio, the branching ratio of the light quantities of the monitor signal versus the principal signal with a second optical coupler 122 which inputs the monitor signal to branch into an FBG input signal and an end signal and which has, as a second prescribed ratio, the branching ratio of the light quantities of the FBG input signal versus the end signal and with a fiber grating 210 which is formed on an optical fiber 144 for transmitting the FBG input signal. The first and the second prescribed ratio are set to be fully attenuated compared with the input signal, in the case where the light reflected by the fiber grating 210 is reflected in the input signal direction through the first and the second optical coupler 121, 122.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength stabilizing module and a stable wavelength laser light generator using a fiber grating, and more particularly to a wavelength stabilizing module using a fiber grating and suppressing the influence of reflected light on a light source. And a stable wavelength laser light generator.

[0002]

2. Description of the Related Art Generally, a wavelength division multiplexing transmission system (WDM) is used.
In this case, when the wavelength interval becomes higher, the interval between adjacent wavelengths becomes shorter. On the other hand, the laser diode generates drift of the center wavelength due to aging and the environment, and crosstalks with adjacent wavelengths to cause interference. Therefore, in order to control the wavelength of the laser diode to be constant, wavelength control is performed by controlling the chip temperature of the laser diode.

FIG. 7 is a block diagram of a conventional wavelength stabilizing module used for wavelength control. In the figure, light from an optical device 1 including a laser diode is output through a fiber 2 and is split by an optical coupler 3 between a fiber 4 and a fiber 5 at a predetermined split ratio (for example, 9: 1). The main signal 8a is transmitted through the fiber 4, and the monitor signal 8a
b is sent to the optical coupler 9. The optical coupler 9 converts the monitor signal 8b into a fiber Bragg grating (FBG) 6
Input signal 8c to be sent to the fiber 10 provided with
And a reference beam 8f to be sent to the fiber 11.

When the FBG 6 is of a transmission type, only light of a specific wavelength is transmitted as signal light 8d, and light of the remaining wavelength band is reflected as reflected light 8e. The signal light 8 d transmitted through the FBG 6 is transmitted to the wavelength adjusting unit 7 connected to the optical device 1.
Is converted into an electric signal by the signal PD module 7a and sent to the voltage converter 7b. On the other hand, the reference light 8f sent from the fiber 11 is converted into an electric signal by the reference PD module 7c and sent to the voltage converter 7d. The optical wavelength control circuit 7e outputs a control signal that reduces the difference between the signal corresponding to the signal light 8d output from the voltage converter 7b and the signal corresponding to the reference light 8f output from the voltage converter 7d. I do. This control signal is for controlling the wavelength of light emitted from the optical device 1 to be kept constant. For example, the temperature of the optical device 1 is adjusted,
Alternatively, the amount of power supplied to the optical device 1 is adjusted.

[0005]

However, in the conventional wavelength stabilizing module described above, the transmission type FBG 6 reflects light having a wavelength other than the wavelength band serving as a signal as reflected light 8e. The reflected light 8e is transmitted through the fiber 10, the optical coupler 9,
In some cases, the laser light is returned to the optical device 1 via the fiber 5, the optical coupler 3, and the fiber 2, and adversely affects a laser light source such as the optical device 1. The influence of the optical device 1 from the reflected light 8e may be further increased when the FBG 6 is a reflection type.

The present invention solves the above-mentioned problems, and
An object of the present invention is to provide a wavelength stabilizing module using a fiber grating and a stable wavelength laser light generator using such a wavelength stabilizing module, in which reflected light returning from a fiber grating to a laser light source is suppressed as much as possible.

[0007]

In order to achieve the above object, a wavelength stabilizing module according to the present invention comprises a first light source for splitting an input signal into a main signal and a monitor signal as shown in FIG. A first optical coupler 121 having a first predetermined ratio in which a branch ratio of the monitor signal to the main signal is equal to a first predetermined ratio; inputting the monitor signal and branching into an FBG input signal and a termination signal; A second optical coupler 122,
A second optical coupler 122 having a second predetermined ratio of a branching ratio of the FBG input signal to the light amount of the termination signal; and a fiber grating 210 formed on an optical fiber 144 for transmitting the FBG input signal. . When the light reflected by the fiber grating 210 is reflected in the direction of the input signal via the second optical coupler 122 and the first optical coupler 121, the first predetermined ratio and the second predetermined ratio are determined. , Are sufficiently attenuated compared to the input signal.

With this configuration, when the light reflected by the fiber grating 210 returns to the input signal direction via the first optical coupler 121 and the second optical coupler 122, the light is sufficiently compared with the input signal. Since it is configured to be attenuated, reflected light returned to the laser light source 110 can be suppressed. The term “sufficiently attenuated” means, for example, an amount of attenuation of −35 dB with respect to an input signal.

Preferably, in the wavelength stabilizing module,
Each of the first predetermined ratio and the second predetermined ratio is 90%
It may be set to 10% or less (about 10 dB or more). More preferably, the value is set such that the sum of the first predetermined ratio and the second predetermined ratio is 26 dB or more. For example, when one is set to 90% to 10% (10 dB), the other is set to 97.5% or more and 2.5% or less (16 dB).
B or more). With this configuration, the return light reflected by the fiber grating is sufficiently attenuated as compared with the input signal.

Preferably, the second optical coupler 122 includes a first light receiving unit 123 for measuring light transmitted through the fiber grating 210 and a fiber grating 210
If the second light receiving means 125 for measuring the light reflected by the laser light source is provided, the connection with the controller 131 for adjusting the wavelength of the laser light generated by the laser light source 110 is established by using the light receiving means 123 and 125. It becomes a wavelength stabilization module that can be easily performed. Preferably, when the termination signal is terminated, return light of the termination signal is eliminated, and reflected light returned to the laser light source 110 can be suppressed.

In order to achieve the above object, a stable wavelength laser light generating apparatus according to the present invention is, for example, as shown in FIG. 1, a wavelength stabilizing module according to any one of claims 1 to 4. A laser light source 110 for generating laser light to be supplied to the wavelength stabilizing module; and a controller 131 for inputting light processed by the wavelength stabilizing module and adjusting the wavelength of the laser light generated by the laser light source 110. And With this configuration, when the controller inputs the light processed by the wavelength stabilization module and stabilizes and controls the wavelength of the laser light generated by the laser light source, the reflection returned to the laser light source by the wavelength stabilization module is performed. Since the light is suppressed, the wavelength controllability becomes stable. In particular, in the wavelength stabilizing module according to claim 3, if each of the first predetermined ratio and the second predetermined ratio is set to 90% or more and 10% or less, the second
Since the light having substantially the same level as the light reflected by the fiber grating 210 is input to the light receiving means 125, the light having substantially the same level as the light reflected by the fiber grating 210 is input to the controller 131. , Wavelength control can be stably performed.

Preferably, in the stable wavelength laser light generator of the present invention, the fiber grating 210 is a reflection type fiber grating, and the second optical coupler 12
2 is a first fiber input side port 122c for inputting the monitor signal, and a reflection type fiber grating 21
The controller 131 includes a second fiber input port 122d for monitoring and outputting the signal light reflected at 0, and the controller 131 monitors the reference light transmitted through the reflection type fiber grating 210 and the second fiber input port 122d from the second fiber input port 122d. The signal light to be output is input to the laser light source 1
A wavelength control signal for controlling the wavelengths of the ten
And the laser wavelength of the laser light source 110 is stabilized in a wavelength band serving as a signal band.

Preferably, in the stable wavelength laser light generator of the present invention, the fiber grating 210 is a transmission type fiber grating, and the second optical coupler 12
2 is a first fiber input side port 122c for inputting the monitor signal, and a transmission type fiber grating 21
The controller 131 includes a second fiber input port 122d for monitoring and outputting the reference light reflected at 0, and the controller 131 monitors the signal light transmitted through the transmission type fiber grating 210 and the second fiber input port 122d from the second fiber input port 122d. The reference light to be output is input to the laser light source 1
A wavelength control signal for controlling the wavelengths of the ten
And the laser wavelength of the laser light source 110 is stabilized in a wavelength band serving as a signal band.

According to an eighth aspect of the present invention, in the stable wavelength laser light generating apparatus according to the sixth or seventh aspect, the controller 131 is configured to control an output value from a signal light receiving means for receiving the signal light. An output value from the reference light receiving unit for receiving the reference light is input, and the following calculation is performed to normalize the wavelength of the signal light to a wavelength band serving as a signal band. It can be easily determined to what degree the wavelength of the light is correct with respect to the wavelength band serving as the signal band. Λ = (PD1-PD2) / (PD1 + PD2) Here, Λ is an index obtained by normalizing the wavelength of the signal light with respect to the wavelength band serving as the signal band, PD1 is the output value of the signal light receiving means, and PD2 is the reference. The output value of the light receiving means.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding members are denoted by the same or similar reference numerals, and duplicate description is omitted. FIG. 1 is a configuration diagram illustrating an embodiment of a stable wavelength laser light generator having a wavelength stabilization module according to the present invention. In the figure, light source 11
Numeral 0 includes a laser diode 111 and a laser drive device 112 for supplying energy to the laser diode 111 to drive it.

An optical fiber 141 is connected to a laser light output section of the laser diode 111, and an optical coupler 121 as a first optical coupler is connected to the fiber 141. From the optical coupler 121, the fiber 142 and the fiber 1
43 branches. The fiber 142 transmits a main signal, and the fiber 143 extracts a part of the main signal as a monitor signal. The branching ratio of the light quantity of the optical coupler 121 is as follows as an example of the first predetermined ratio. [Main signal of fiber 142]: [Monitor signal of fiber 143] = 95: 5 (1)

The fiber 143 is further connected to an optical coupler 122 as a second optical coupler.
The fiber 145 branches from the second fiber output port 122b. The branching ratio between the FBG input signal of the fiber 144 and the light amount of the terminal signal of the fiber 145 in the optical coupler 122 is as follows as an example of the second predetermined ratio. [FBG input signal of fiber 144]: [termination signal of fiber 145] = 5: 95 (2)

The fiber 144 has a P
A D (photodiode) module 123 is connected, and a fiber Bragg grating (FBG) 210 is formed in the fiber 144 between the optical coupler 122 and the PD module 123. FBG2
Reference numeral 10 denotes a diffraction grating that is configured to periodically change the refractive index in the length direction, and includes a reflection type and a transmission type. Here, a description will be given as a reflection type fiber grating. On the other hand, the fiber 145 is terminated.
Since the termination processing has been performed, the light guided to the fiber 145 is diffused and does not return to the fiber 145 again. The termination 127 may be one in which the termination module is connected to the end of the optical fiber, or may be one in which the optical fiber is simply damaged.

The optical coupler 122 is connected to the first fiber input side port 122 c to which the fiber 143 is connected, and to the fiber 14 reflected by the fiber grating 210.
A second fiber input port 122d for monitoring and outputting the signal light of No. 4 is provided. Fiber input side port 122
Although c and 122d are called ports, there is no need to cut the optical fiber here, and the optical fiber and the optical coupler 122 are actually configured continuously. One end of the fiber 146 is connected to the second fiber input side port 122d,
The other end is connected to a PD module 125 as light receiving means. Fiber input side port 12 of optical coupler 122
Fibers 143 and 146 are branched from 2c and 122d, respectively. The band wavelength component serving as the signal light in the FBG input signal of the fiber 144 is reflected by the reflection type fiber grating 210, and is branched by the optical coupler 122 into the signal light of the fiber 146 and the return light of the fiber 143. This branching ratio has the same value as equation (2),
It looks like this: [Signal light of fiber 146]: [return light of fiber 143] = 95: 5 (3)

The PD modules 123 and 125 are modules for converting an optical signal into an electric signal.
51 and 154 are connected. These wires are connected to the calculator 126. Arithmetic unit 126 includes a subtractor, and detects an increase or decrease in a variable transmitted by a signal from PD module 123, using a variable transmitted by a signal from PD module 125 as a reference amount. Here, the signal light of the fiber 146 is about 95% of the reflection component of the FBG input signal reflected by the reflection type fiber grating 210, that is, FB.
Since this is the majority of the signal band wavelength of the G input signal, the light amount level is almost balanced, and the calculation in the calculator 126 can be performed stably without performing a large gain adjustment. The increase / decrease of the variable to be adjusted with respect to the reference amount detected in this manner is determined by the electric wire 153 connected to the output side of the calculator 126.
Is transmitted to the control device 131 through. Control device 131
Are electrically connected to the energy supply device 112.

In the above apparatus, the optical coupler 122, P
D modules 123 and 125, FBG210, arithmetic unit 1
26, a wavelength stabilizing module according to an embodiment is configured. Further, a light source 110 and a control device 131 configure a stable wavelength laser light generating device according to an embodiment.

With reference to FIG. 1, the operation of the wavelength stabilizing module and the stable wavelength laser light generator having the above-described configuration will be described. The laser light emitted from the laser diode 111 passes through the core of the fiber 141 and passes through the optical coupler 121.
To reach. Here, the main signal is supplied through a fiber 142 to an optical communication system such as a wavelength division multiplexing transmission system (WDM). A part of the main signal is used as a monitor signal for the optical coupler 1.
At 21, it is extracted to the fiber 143 and sent to the optical coupler 122. Here, the monitor signal is split into two and sent to the fiber grating 210 and the end 127 through the fibers 144 and 145, respectively. The FBG input signal sent to the fiber 144 reaches the fiber grating 210, where only light of a specific wavelength is reflected as signal light, passes again through the fiber 144, the optical coupler 122, and passes through the fiber 146 through the PD. Sent to module 125. On the other hand, light of other wavelengths passes through the fiber grating 210 and is used as reference light in the PD module 123.
Sent to The signal sent to fiber 145 is
7, there is no signal returning to the optical coupler 122.

At this time, the fiber grating 210
The return light to the fiber 143 with respect to the FBG input signal of the fiber 144 reflected by the optical coupler 122 is reduced to about 5% by the optical coupler 122, and the return light returned through the fiber 143 enters the optical coupler 121 and enters the optical coupler 121. % Return light and enters the fiber 141. Therefore, fiber 1
When the return light of 43 returns to the light source 110 via the optical coupler 121, the reflected light returning to the light source 110 is very slight. Thus, according to the present embodiment, FBG2
The return light of the fiber 143 reflected from the light source 10
The effect on zero is almost negligible. The reflected light returned to the light source is preferably -35 dB or less, more preferably -40 dB or less. In the present embodiment, the optical coupler 121, the optical coupler 122, the FBG2
10, the optical coupler 122, and the optical coupler 121, respectively, so that the total attenuation is 13 (fiber 141 → fiber 143) +13 (fiber 143 → fiber 144).
+3 (fiber 144 → fiber grating 210
→ fiber 144) +13 (fiber 144 → fiber 143) +13 (fiber 143 → fiber 141) =
55 dB, which achieves the preferable level.

Next, laser wavelength control will be described. An electric signal transmitted from the PD module 123 through the electric wire 151 is guided to a subtractor (not shown) inside the calculator 126. Also, the electric wire 1 from the PD module 125
The electric signal transmitted through 54 is gain-adjusted by a gain adjuster (not shown) inside arithmetic unit 126, and is then guided to a subtractor inside arithmetic unit 126 as a reference signal. The result of the subtraction is fed back to the control device 131 through the electric wire 153.

The controller 131 adjusts the wavelength of the laser light emitted from the light source 110 so that the guided signal becomes zero. For adjusting the wavelength of the laser light, for example, a Peltier current controller and a Peltier element for adjusting the temperature of the laser diode 111 are used. According to the Peltier device, the laser diode 111 can be heated or cooled using the current signal. The wavelength to be adjusted can be set to a predetermined wavelength by determining a gain K provided by a gain adjuster inside the arithmetic unit 126. That is, the wavelength / P in FIG.
As shown in the D output diagram (xy diagram), the FBG 210
Has a slope according to the characteristic.

If the wavelength to be locked as the main signal is x0
And the PD output corresponding to x0 on the characteristic curve is y0. PD of transmitted light of FBG210 at a certain time
Assume that the output is y and the corresponding output is x.
By applying a gain K to the signal from the PD module 125, the output is set to y0. If there is a difference between y and y0, the output y-y0 of the subtractor does not become zero. The controller 131 adjusts the wavelength of the light emitted from the light source 110 so that the difference becomes zero. In this manner, the wavelength controller can control the wavelength of light, and the laser light generator can stably generate a desired wavelength.

The control device 131 is a PD module 12
5 is used. This signal light reflects the laser light generated by the laser diode (LD) 111 by the reflection type fiber grating, and thus directly reflects the power of the laser light. Therefore, even if the power of the laser beam fluctuates somewhat, the PD module 1
By performing feedback control using the signal light from the optical signal 25, control for stabilizing power can be easily performed.

Although the case where the branch ratio of the incident light or the reflected light in the optical coupler 121 and the optical coupler 122 is a branch ratio of 95: 5 has been described as an example, the light source 110 is required as in the case of 98: 2 or 80:20. From the FBG input signal reflected by the fiber grating 210 in the path from the optical coupler 121, the optical coupler 122, and the PD module 123 to the light source 110, any light source light amount having a small ratio of return light returning to the light source 110 may be used. It is preferable that the ratio of the return light is, for example, attenuated by 35 dB or more.

FIG. 2 shows a signal PD module and a reference PD.
It is an explanatory view of the signal conversion characteristics of the module, the horizontal axis is the wavelength λ,
The vertical axis indicates the PD module output voltage. Here, since the reflection type fiber grating is described as an example, the PD module 125 corresponds to the signal PD module, and the PD module 123 corresponds to the reference PD module. The signal conversion characteristic of the signal PD module has a wavelength component reflected by the reflection type fiber grating, and has a bell-shaped curve shape in a wavelength band of a center wavelength λ ₀ and a half width λb. The signal conversion characteristic of the reference PD module has a wavelength component transmitted through the reflection type fiber grating, and the signal conversion characteristic of the signal PD module and the constant output line in the region of wavelength λ (1530 nm to 1560 nm in the case of WDM). It is line symmetric. The wavelength λs is a wavelength fixed by the fiber grating 210.

FIG. 3 is an explanatory diagram of the operation characteristics of the operation unit 126. The horizontal axis indicates the wavelength λ, and the vertical axis indicates the operation value. The arithmetic unit 126 calculates an index Λ obtained by normalizing the wavelength of the actual signal light with respect to the wavelength band allocated as the signal band by the following equation. Λ = (PD1-PD2) / (PD1 + PD2) (4) where PD1 is the PD output value of the signal PD module, P
D2 indicates a PD output value of the reference PD module. The index Λ has a bell-shaped curve shape in a wavelength band having a center wavelength λ ₀ and a half-value width λb, and has a maximum value of +1 in a wavelength band (for example, 0.8 nm) serving as a signal band. It takes a negative value in wavelength bands other than the band,
The minimum value is -1. The optimal wavelength as the wavelength of the signal light is a point where the slope of the index Λ in the direction of the wavelength λ is the steepest. For example, in FIG.
s and λs−λb are desirable.

FIG. 4 is a configuration diagram of the optical coupler 122 having four branched fibers. As shown, the fibers 144, 145 have a Y-shaped fusion splice. Also,
The fibers 143 and 146 also have a Y-shaped fused portion. The branch ratio of the light amount of each fiber is selected to be a shape that satisfies the formulas (2) and (3), for example, the ratio of the thickness of the fiber.

Next, a comparative example of the stable wavelength laser light generator will be described with reference to FIGS. 5, 6, and 7. FIG. The comparative example uses the apparatus of FIG. 7 described as a conventional apparatus. here,
7, the optical couplers 3 and 9 correspond to the optical couplers 121 and 122 of the apparatus of FIG. 1, and the signal PD module 7a of the apparatus of FIG. 7 corresponds to the PD module 125 of the apparatus of FIG. The reference PD module 7c in the device of FIG. 7 corresponds to the PD module 123 in the device of FIG.

FIG. 5 shows a signal PD module and a reference PD.
It is an explanatory view of the signal conversion characteristics of the module, the horizontal axis is the wavelength λ,
The vertical axis indicates the PD output voltage. The signal conversion characteristic of the signal PD module 7a has a bell-shaped curve shape in the wavelength band of the center wavelength λ ₀ and the half width λb due to the transmission characteristics of the fiber grating. Reference PD module 7
Since the signal conversion characteristic of c does not pass through the fiber grating, it is flat regardless of the wavelength λ.

FIG. 6 is an explanatory diagram of the calculation characteristics of the calculator 126. The horizontal axis represents the wavelength λ, and the vertical axis represents the calculation value. The arithmetic unit 126 calculates an index Λ obtained by normalizing the wavelength of the signal light with respect to the wavelength band serving as the signal band, using the above-described equation (4). The exponent 釣 has a bell-shaped curve shape in a wavelength band having a center wavelength λ ₀ and a half-value width λb, has a positive value in a wavelength band serving as a signal band (for example, 0.8 nm), and has a value other than the signal band. It takes a negative value in the wavelength band, and its minimum value is -1. Comparing the characteristic diagram of FIG. 3 with the characteristic diagram of FIG. 6, the embodiment of the present invention has a
It can be seen that the maximum value of the positive value of the index Λ is large, and the response is sharpened and improved.

In the above embodiment, the signal light and the reference light are described by taking the reflection type fiber grating as an example. However, the present invention is not limited to this, and may be a transmission type fiber grating. In the case of the transmission type fiber grating, the relationship between the signal light and the reference light is opposite to that in the case of the reflection type fiber grating. Further, in the above-described embodiment, the PD (photodiode) module has been described as the light receiving means. However, the present invention is not limited to this, and any module that generates an electric signal corresponding to the light receiving signal can be used. Good.

[0036]

As described above, according to the wavelength stabilizing module of the present invention, the first optical coupler for branching an input signal into a main signal and a monitor signal is provided. A first optical coupler having a first predetermined ratio, and a second optical coupler for receiving the monitor signal and branching into an FBG input signal and a termination signal, wherein the FBG input signal and the termination signal are coupled. A second optical coupler having a signal light branching ratio of a second predetermined ratio, and a fiber grating formed on an optical fiber transmitting the FBG input signal;
The first predetermined ratio and the second predetermined ratio are such that the light reflected by the fiber grating is transmitted to the first optical coupler and the second optical coupler.
When the light is reflected in the direction of the input signal via the optical coupler, the light is selected to be sufficiently attenuated as compared with the input signal, so that the reflected light returned to the laser light source can be suppressed. .

Further, according to the stable wavelength laser light generating apparatus of the present invention, the wavelength stabilizing module, a laser light source for generating a laser beam to be supplied to the wavelength stabilizing module, and a laser beam processed by the wavelength stabilizing module. Controller that adjusts the wavelength of the laser light generated by the laser light source by inputting the reflected light, so that the amount of reflected light returned to the laser light source is small, and the wavelength of the generated laser light is controlled to a constant value. Can be easily performed. Further, the case where the normalization operation is performed as in claim 8 corresponds to the case shown in FIG. 2, and since the exponent Λ becomes steep, the response characteristic is good and the wavelength of the laser beam is controlled to a constant value. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a stable wavelength laser light generator having a wavelength stabilization module of the present invention.

FIG. 2 is an explanatory diagram of signal conversion characteristics of a signal PD module and a reference PD module used in the embodiment of the present invention.

FIG. 3 is an explanatory diagram of operation characteristics of an operation unit used in the embodiment of the present invention.

FIG. 4 is an optical coupler 1 having four branched fibers.
FIG.

FIG. 5 is a comparative example of a signal PD module and a reference PD.
FIG. 4 is an explanatory diagram of signal conversion characteristics of a module.

FIG. 6 is an explanatory diagram of operation characteristics of an operation unit of a comparative example.

FIG. 7 is a configuration diagram of a wavelength stabilization module used for conventional wavelength control.

[Explanation of symbols]

Reference Signs List 110 light source 111 laser diode 112 energy supply device 121, 122 optical coupler 123, 125 PD (photodiode) module 126 arithmetic unit 131 control device 141, 142, 143, 144, 145, 146 optical fiber 210 fiber grating

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Ichioka 585 Tomicho, Funabashi-shi, Chiba Sumitomo Osaka Cement Co., Ltd. New Technology Research Laboratory (72) Inventor Junichiro Ichikawa 585 Tomicho, Funabashi-shi, Chiba Sumitomo Osaka Cement Shares 2H050 AB05X AC84 AD00 AD16 5F073 AB25 AB28 BA01 EA03 FA05 FA25 GA02 GA13 GA22

Claims (8)

[Claims] 1. A first optical coupler for branching an input signal into a main signal and a monitor signal, wherein the branch ratio of the monitor signal to the light amount of the main signal is a first predetermined ratio. A second optical coupler for inputting the monitor signal and branching into an FBG input signal and a termination signal, wherein the branch ratio between the FBG input signal and the light quantity of the termination signal is a second predetermined ratio. An optical coupler; and a fiber grating formed on an optical fiber for transmitting the FBG input signal;
When the light reflected by the fiber grating returns to the input signal direction via the second optical coupler and the first optical coupler, the first predetermined ratio and the second predetermined ratio correspond to the input signal. A wavelength stabilizing module characterized by being selected to be sufficiently attenuated in comparison. 2. The wavelength stabilizing module according to claim 1, wherein each of the first predetermined ratio and the second predetermined ratio is set to 90% or more and 10% or less. 3. The second optical coupler is provided with first light receiving means for measuring light transmitted through the fiber grating, and second light receiving means for measuring light reflected by the fiber grating. The wavelength stabilizing module according to claim 1 or 2, wherein: 4. The wavelength stabilizing module according to claim 1, wherein said wavelength stabilizing module is configured to terminate said termination signal. 5. The wavelength stabilizing module according to claim 1, a laser light source for generating a laser beam to be supplied to the wavelength stabilizing module, and a processing performed by the wavelength stabilizing module. A controller for inputting the selected light and adjusting the wavelength of the laser light generated by the laser light source. 6. The fiber grating according to claim 1, wherein the fiber grating is a reflection type fiber grating;
A first fiber input port for inputting the monitor signal; and a second fiber input port for monitoring and outputting the signal light reflected by the reflection type fiber grating; The reference light transmitted through and the signal light monitored and output from the second fiber input port are input, and a wavelength control signal for controlling the wavelength of the laser light source is fed back to the laser light source. The stable wavelength laser light generator according to claim 5, wherein the laser wavelength of the laser light source is stabilized to a wavelength band serving as a signal band. 7. The fiber grating is a transmission type fiber grating; the second optical coupler comprises:
A first fiber input port for inputting the monitor signal; and a second fiber input port for monitoring and outputting the reference light reflected by the transmission fiber grating; the controller comprises: the transmission fiber grating; And a reference light monitored and output from the second fiber input port, and a wavelength control signal for controlling the wavelength of the laser light source is fed back to the laser light source. The stable wavelength laser light generator according to claim 5, wherein the laser wavelength of the laser light source is stabilized to a wavelength band serving as a signal band. 8. The controller inputs an output value from a signal light receiving unit for receiving the signal light and an output value from a reference light receiving unit for receiving the reference light, and performs the following calculation. 8. The stable wavelength laser light generator according to claim 6, wherein the wavelength of the signal light is normalized with respect to a wavelength band serving as a signal band. Λ = (PD1-PD2) / (PD1 + PD2) Here, Λ is an index obtained by normalizing the wavelength of the signal light with respect to the wavelength band serving as the signal band, PD1 is the output value of the signal light receiving means, and PD2 is the reference. The output value of the light receiving means.