JP2006049785A - Wavelength variable light source, and distortion measurement equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength variable light source that falsely makes mode hop free by lengthening a resonator length so as to oscillate in multimode. <P>SOLUTION: A wavelength variable light source has: a semiconductor laser (LD) 1; a collimate lens 2 that collimates light emitted from an AR-coated end face of the LD 1; a diffraction grating 3 that receives collimated light emitted from the collimate lens 2 and diffracts it at an angle complying with a wavelength; a mirror 4 that receives light diffracted based on the collimated light emitted from the diffraction grating 3 and reflects it to the diffraction grating 3; and an angle adjusting means 5 that, when the light reflecting at the mirror 4, entering the diffraction grating 3, and being again diffracted (now as diffracted light) is made to enter the LD 1 via the collimate lens 2, changes the mirror 4's angle such that the diffracted light entering the LD 1 becomes a light with a desired wavelength. In the light source, the resonator's length is made so long by installing an optical fiber 6 with a specific length between the LD 1 and the collimate lens 2 as to multimode-oscillate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an external resonance-type wavelength tunable light source using a semiconductor laser and a strain measurement apparatus using the same, and in particular, by making the resonator length long so as to oscillate in multiple modes, it is made pseudo-hop-free. The present invention relates to a wavelength tunable light source and a strain measurement apparatus using the same.

  For measuring the wavelength characteristics of optical components and measuring strain using FBG (Fiber Bragg Grating), which has been in practical use in recent years, the intensity or wavelength change of light output from the measurement target is detected. An ASE (Amplified Spontaneous Emission) light source for inputting broadband light to the optical spectrum analyzer is used. However, since this ASE light source has a wavelength band, an intensity, and an intensity deviation of the output light of, for example, about 30 nm, about −13 dBm / nm, and several dB, respectively, the wavelength characteristics of a wider band and a high dynamic range are obtained. It was not possible to satisfy the demands for measurement and the desire to enable the use of FBG in a more remote and wide area.

  On the other hand, unlike the above-described measurement method using the ASE light source having wavelength selectivity on the light receiving side, there is a measurement method in which a variable wavelength light source and an optical power meter (light receiver) provided on the light source side are combined. there were. In this case, the wavelength variable light source has the wavelength band, intensity, and intensity change of the output light of about 100 nm, about +10 dBm, and about 1 dB, respectively, and can satisfy the above requirements. As such a wavelength variable light source, an external resonance type wavelength variable light source called a Littman type is well known. (For example, see Patent Document 1)

  FIG. 20 shows a schematic configuration of this type of external resonance type tunable light source. This wavelength tunable light source converts the light emitted from the end surface of the semiconductor laser (LD) 1 that has been AR-coated (AR) into collimated light (parallel light) by the collimator lens 2 and enters the diffraction grating 3. Then, the diffracted light emitted from the diffraction grating 3 with respect to the incident light is incident on the mirror 4 supported by the angle adjusting means 5 so as to be able to rotate around a predetermined position P on the surface obtained by extending the diffraction surface. The reflected light reflected by the mirror 4 is incident on the diffraction grating 3, and the diffracted light with respect to the reflected light is returned from the diffraction grating 3 to the LD 1 through the collimator lens 2.

  As a result, only the wavelength component orthogonal to the reflecting surface of the mirror 4 returns to the LD 1 among the wavelength components of the light emitted from the LD 1, and the LD 1 is excited (resonated) with the returned specific wavelength light. Then, the light having the specific wavelength (resonance wavelength) is emitted from the end face that is not AR-coated as output light. This resonance wavelength is an external resonance mode based on the diffraction wavelength characteristic determined by the angle of the mirror 4 with respect to the diffraction grating 3 and the resonator length from the end surface of the LD 1 not coated with AR to the reflection surface of the mirror 4 via the diffraction grating 3. By rotating the mirror 4 around the predetermined position P by the angle adjusting means 5, the diffraction wavelength characteristic and the external resonance mode are changed simultaneously as shown in FIG. Thus, the resonance wavelength can be continuously varied. This Littman-type tunable light source is excellent in wavelength selectivity because the diffraction grating 3 performs diffraction twice (selection of a specific wavelength), that is, the diffraction wavelength characteristic is steep and high. It is characterized by being able to oscillate coherent light.

JP 2001-284715 A

  However, in such a conventional external resonance type tunable light source, the predetermined position P on the surface obtained by extending the diffraction surface of the diffraction grating 3 for rotating the mirror 4 can be theoretically described in more detail. For example, it is necessary to position the mirror 4 on the surface where the reflection surface is extended and on the surface where the end surface of the LD 1 which is not AR-coated is extended. The mechanism for enabling the adjustment of the rotating shaft in 5) is complicated, and much labor and time are required for the adjustment.

  Even if the adjustment is successful, when the wavelength is changed by rotating the mirror 4, the relative relationship between the diffraction wavelength characteristic and the external resonance mode is broken due to the influence of temperature fluctuation, vibration, etc. A mode hop (external resonance mode changes) occurred. Further, the resonator length is shortened to, for example, about several millimeters so that the single mode oscillation is originally performed, and as shown in FIG. 15B, the number of external resonance modes that fall within the diffraction wavelength characteristic band is as small as possible ( In other words, as a result of widening the external resonance mode interval Δλ, the wavelength change due to the mode hop was as large as several GHz in frequency.

  Further, when the wavelength characteristic of the optical component is measured using the highly coherent light output from the external resonance type wavelength tunable light source, as shown in FIG. 16, about 3 dB generated by reflection on the optical fiber, the optical component or the like. There is a drawback in that the ripples of the superposition are superimposed on the wavelength characteristics, making it difficult to grasp the original characteristics.

  The present invention solves these problems by increasing the length of the resonator so as to oscillate in multiple modes, and provides a tunable light source that is quasi-mode-hop-free and a distortion measurement device using the same. It is aimed.

  In order to solve the above-described problem, in the wavelength tunable light source according to the first aspect of the present invention, the semiconductor laser (1) on which one laser light emission end face is AR-coated and the AR-coated end face of the semiconductor laser A collimating lens (2) for collimating the emitted light, a diffraction grating (3) for receiving the collimated light emitted from the collimating lens and diffracting it at an angle according to the wavelength, and the collimating emitted from the diffraction grating A mirror (4) that receives the diffracted light with respect to the light and reflects it to the diffraction grating, and the reflected light from the mirror is incident on the diffraction grating and diffracted again, and the diffracted light obtained thereby passes through the collimating lens. The angle at which the angle of the mirror is changed so that the diffracted light incident on the semiconductor laser becomes light of a desired wavelength when incident on the semiconductor laser. A tunable light source that oscillates in an external resonance mode based on a resonator length formed between the other laser beam emitting end face of the semiconductor laser and the mirror, However, the resonator length is such that light oscillating in the external resonance mode based on the resonator length becomes light by multimode oscillation.

  Further, in the wavelength tunable light source according to the second aspect of the present invention, the semiconductor laser (1) in which one laser light emitting end face is AR-coated and light emitted from the AR-coated end face of the semiconductor laser is collimated. A collimating lens (2), a diffraction grating (3) that receives the collimated light emitted from the collimating lens and diffracts it at an angle corresponding to the wavelength, a reflector (35), and a reflector driving means (50). The diffracted light with respect to the collimated light that is configured to be incident and is incident from the diffraction grating is reflected by the reflecting surface of the reflector to the diffraction grating, and is again diffracted by the diffraction grating. Is incident on the semiconductor laser through the collimating lens, the angle of the reflecting surface of the reflector so that the diffracted light incident on the semiconductor laser becomes light of a desired wavelength. An external resonance mode based on a resonator length, which comprises a MEMS scanner (60) that is changed by the reflector driving means, and is configured between the other laser light emitting end face of the semiconductor laser and the reflecting face of the reflector. The wavelength tunable light source that oscillates at the resonator length is such that the resonator length is such that light that oscillates in an external resonance mode based on the resonator length becomes light by multimode oscillation.

  In the wavelength tunable light source according to a third aspect of the present invention, the reflector of the MEMS scanner in the above-described wavelength tunable light source according to the second aspect includes a fixed substrate (36, 37) and predetermined edges from the fixed substrate. A shaft portion (38, 39) that is extended by a predetermined length in width and can be twisted and deformed along the length direction, and is connected to the tip of the shaft portion by its own edge portion, A reflector (40) provided with the reflecting surface for reflecting the diffracted light from the diffraction grating, and the reflector driving means of the MEMS scanner includes a shaft portion of the reflector and a reflector. A force is applied to the reflecting plate by a drive signal having a frequency corresponding to the natural frequency of the portion made of the plate, and the reflecting plate is reciprocally rotated at the natural frequency or a frequency close thereto.

  In the wavelength tunable light source according to a fourth aspect of the present invention, in the wavelength tunable light source according to any one of the first to third aspects described above, an optical fiber (6) having a predetermined length between the semiconductor laser and the collimating lens. ).

  In the wavelength tunable light source according to claim 5 of the present invention, in the wavelength tunable light source according to any one of claims 1 to 3, a spatial propagation path having an optical path length of 15 cm or more between the collimating lens and the diffraction grating. (17).

  In the wavelength tunable light source according to claim 6 of the present invention, in the wavelength tunable light source according to claim 5, the spatial propagation path is configured to include a corner cube (17 a).

  In the wavelength tunable light source according to a seventh aspect of the present invention, the wavelength tunable light source according to any one of the first to sixth aspects described above is provided on an optical path through which the 0th-order light of the diffraction grating is emitted and has a predetermined wavelength. An optical resonator (7) that transmits the first light, and a first light receiver (8) that receives the transmitted light emitted from the optical resonator and converts it into a first electric signal, The wavelength of the emitted light of the semiconductor laser can be obtained from the first electric signal output from the light receiver.

  In the wavelength tunable light source according to the eighth aspect of the present invention, in the wavelength tunable light source according to any one of the first to sixth aspects described above, the 0th-order light of the diffraction grating is output light.

  In the wavelength tunable light source according to claim 9 of the present invention, the wavelength tunable light source according to claim 8 is provided on an optical path from which the 0th order light of the diffraction grating is emitted, and the 0th order light is divided into two. An optical branching means (16) for branching and emitting one zero-order light as the output light, and an optical resonator for receiving the other zero-order light emitted from the optical branching means and transmitting light of a predetermined wavelength (7) and a first light receiver (8) that receives the transmitted light emitted from the optical resonator and converts the transmitted light into a first electric signal, and is output from the first light receiver. The wavelength of the emitted light of the semiconductor laser can be obtained from the first electric signal.

  In the wavelength tunable light source according to claim 10 of the present invention, a semiconductor laser (1) in which one laser light emitting end face is AR-coated and light emitted from the AR-coated end face of the semiconductor laser is collimated. A collimating lens (2) that receives the collimated light emitted from the collimating lens and diffracts the collimated light at an angle corresponding to the wavelength, and diffracted light for the collimated light emitted from the diffraction grating. The mirror (4) that reflects the diffraction grating and the reflected light from the mirror enter the diffraction grating and are diffracted again, and the resulting diffracted light enters the semiconductor laser via the collimator lens. Angle adjusting means (5) for changing the angle of the mirror so that the diffracted light incident on the semiconductor laser becomes light of a desired wavelength. In a wavelength tunable light source that oscillates in an external resonance mode based on a resonator length formed between the other laser beam emission end face of the semiconductor laser and the mirror, the semiconductor laser is disposed between the semiconductor laser and the collimating lens. An optical fiber (6) that receives light emitted from the AR-coated end face of the semiconductor laser, transmits the light for a predetermined length, and enters the collimator lens is provided.

  In the wavelength tunable light source according to an eleventh aspect of the present invention, a semiconductor laser (1) on which one laser light emitting end face is AR-coated and light emitted from the AR-coated end face of the semiconductor laser are received. An optical fiber (6) for transmitting a predetermined length, a collimating lens (2) for receiving and collimating light emitted from the optical fiber, and receiving collimated light emitted from the collimating lens according to the wavelength. A diffraction grating (3) that diffracts at an angle, a reflector (35), and reflector drive means (50) are configured, and diffracted light with respect to the collimated light incident from the diffraction grating is reflected on the reflector. Reflected by the reflecting surface to the diffraction grating and again diffracted by the diffraction grating, and the diffracted light obtained thereby is transmitted through the collimating lens and the optical fiber to the semiconductor laser. A MEMS scanner (60) for changing the angle of the reflecting surface of the reflector by the reflector driving means so that the diffracted light incident on the semiconductor laser becomes light of a desired wavelength when incident. The semiconductor laser oscillates in an external resonance mode based on a resonator length formed between the other laser light emitting end surface of the semiconductor laser and the reflecting surface of the reflector.

  The tunable light source according to claim 12 of the present invention is the tunable light source according to claim 11, wherein the reflector of the MEMS scanner is fixed to the fixed substrate (36, 37) and the edge of the fixed substrate. A shaft portion (38, 39) that is extended by a predetermined length in width and can be twisted and deformed along the length direction, and is connected to the tip of the shaft portion by its own edge portion, A reflector (40) provided with the reflecting surface for reflecting the diffracted light from the diffraction grating, and the reflector driving means of the MEMS scanner includes a shaft portion of the reflector and a reflector. A force is applied to the reflecting plate by a drive signal having a frequency corresponding to the natural frequency of the portion made of the plate, and the reflecting plate is reciprocally rotated at the natural frequency or a frequency close thereto.

  According to a tunable light source of a thirteenth aspect of the present invention, in the tunable light source according to any one of the tenth to twelfth aspects described above, the tunable light source is further provided on an optical path through which the zero-order light of the diffraction grating is emitted. An optical resonator (7) that transmits light having a wavelength of 1 and a first light receiver (8) that receives the transmitted light emitted from the optical resonator and converts it into a first electric signal, The wavelength of the emitted light of the semiconductor laser can be obtained from the first electric signal output from one light receiver.

  In the strain measurement apparatus using the wavelength tunable light source according to the fourteenth aspect of the present invention, the light having a predetermined wavelength range is oscillated, and the light is incident on the fiber Bragg grating (15a, 15b) as the measurement light. The wavelength tunable light source (100) according to any one of claims 1 to 13, and the measurement light incident on the fiber Bragg grating, the light reflected by the fiber Bragg grating or the light transmitted through the fiber Bragg grating The second light receiver (12) that receives and converts it into a second electric signal, the second electric signal output from the second light receiver, and the mirror output from the wavelength variable light source or Based on the signal for changing the angle of the reflecting surface of the reflector, a variation in distortion applied to the fiber Bragg grating is obtained. And a processing unit (13).

  In the strain measuring apparatus using the wavelength tunable light source according to the fifteenth aspect of the present invention, the light in a predetermined wavelength range is oscillated and incident on the fiber Bragg grating (15a, 15b) as the measuring light. The wavelength tunable light source (100) according to any one of claims 7, 9 and 13, and the measurement light incident on the fiber Bragg grating, which is reflected by the fiber Bragg grating or transmitted through the fiber Bragg grating. The second light receiver (12) that receives the received light and converts it into a second electric signal, the second electric signal output from the second light receiver, and the output from the variable wavelength light source Variation in distortion applied to the fiber Bragg grating based on a signal for changing the angle of the mirror or the reflecting surface of the reflector And obtaining the first electric signal output from the first light receiver and the signal for changing the angle of the reflecting surface of the mirror or the reflector output from the wavelength variable light source. And processing means (13) for determining the wavelength of the emitted light of the semiconductor laser.

  In the wavelength tunable light source according to the first aspect of the present invention, the resonator length is set so as to oscillate multi-mode, so that the external resonance mode interval can be narrowed, thereby reducing the mode hop interval and pseudo mode hop free. It can be. Further, low-coherent light is output by multimode oscillation, and it is possible to improve the superposition of ripple due to reflection when measuring the wavelength characteristics of optical components, which is a drawback of conventional high-coherent light.

  In the wavelength tunable light source according to the second aspect of the present invention, the resonator length is set to a length allowing multi-mode oscillation, and the mirror for reflecting the diffracted light from the diffraction grating and the angle adjusting means of the mirror are configured by a MEMS scanner. As a result, the external resonance mode interval can be narrowed, whereby the mode hop interval is also narrowed, making it possible to make the mode hop free. Further, low-coherent light is output by multimode oscillation, and it is possible to improve the superposition of ripple due to reflection when measuring the wavelength characteristics of optical components, which is a drawback of conventional high-coherent light. Further, the wavelength can be increased at high speed and the apparatus can be downsized.

  In the wavelength tunable light source according to claims 3 and 12 of the present invention, the reflector of the MEMS scanner for reflecting the diffracted light from the diffraction grating is extended from the fixed substrate and its edge with a predetermined width and a predetermined length, The reflector includes a shaft portion that can be twisted and deformed along its length direction, and a reflector plate that is connected to the tip of the shaft portion at its edge and has a reflective surface on one side. A force is applied to the reflecting plate by an electric signal having a frequency corresponding to the natural frequency of the portion composed of the shaft portion and the reflecting plate, so that the reflecting plate is reciprocally rotated at the natural frequency or a frequency close thereto. For this reason, the reflection plate can be reciprocated at high speed, and since the center of rotation is in the reflection plate, the change in the reflection angle of the diffracted light incident on the reflection surface of the reflection plate with respect to the angle change The amount can be increased. Thereby, the wavelength variable speed can be increased.

  In the wavelength tunable light source according to the fourth aspect of the present invention, since the optical fiber having a predetermined length is provided between the semiconductor laser and the collimating lens, the resonator length is set to a length allowing multimode oscillation. Can do.

  In the wavelength tunable light source according to the fifth aspect of the present invention, since the spatial propagation path having an optical path length of 15 cm or more is provided between the collimating lens and the diffraction grating, the resonator length is set to a length that allows multimode oscillation. can do.

  In the wavelength tunable light source according to the sixth aspect of the present invention, since the spatial propagation path is configured to include the corner cube, the apparatus can be miniaturized by folding the spatial propagation path.

  In the wavelength tunable light source according to the seventh and thirteenth aspects of the present invention, the light of the predetermined wavelength of the zero-order light of the diffraction grating is converted into an electric signal, and the wavelength of the output light is obtained using this electric signal. Can do.

  In the wavelength tunable light source according to the eighth aspect of the present invention, since the 0th-order light of the diffraction grating is used as the output light, the intensity fluctuation of the output light caused by the influence of the internal resonance mode of the semiconductor laser can be reduced. Specifically, it can be about 1/10 of the intensity fluctuation (about 1 dB) when the light emitted from the end surface of the semiconductor laser not coated with AR is used as the output light.

  In the wavelength tunable light source according to the ninth aspect of the present invention, the 0th-order light of the diffraction grating is used as output light, and light of a predetermined wavelength of this 0th-order light is converted into an electrical signal. The intensity fluctuation of the output light caused by the influence of the resonance mode can be reduced, and the wavelength of the output light can be obtained using the electric signal.

  In the wavelength tunable light source according to the tenth aspect of the present invention, since the resonator length is increased by using the optical fiber, the external resonance mode interval can be narrowed, thereby the mode hop interval is also narrowed and the mode hop free. It can be. Further, low-coherent light is output by multimode oscillation, and it is possible to improve the superposition of ripple due to reflection when measuring the wavelength characteristics of optical components, which is a drawback of conventional high-coherent light.

  In the wavelength tunable light source according to the eleventh aspect of the present invention, the resonator length is increased by using an optical fiber, and the mirror for reflecting the diffracted light from the diffraction grating and the angle adjusting means of the mirror are configured by a MEMS scanner. As a result, the external resonance mode interval can be narrowed, whereby the mode hop interval is also narrowed, and the mode hop can be made free. Further, low-coherent light is output by multimode oscillation, and it is possible to improve the superposition of ripple due to reflection when measuring the wavelength characteristics of optical components, which is a drawback of conventional high-coherent light. Further, the wavelength can be increased at high speed and the apparatus can be downsized.

  In the strain measuring apparatus using the wavelength tunable light source according to the fourteenth aspect of the present invention, the strain measuring apparatus is configured using the wavelength tunable light source according to any one of the first to thirteenth aspects described above. By using hop-free and low-coherent light, fluctuations in distortion applied to the fiber Bragg grating can be stably measured with little ripple.

  In the strain measuring apparatus using the wavelength tunable light source according to the fifteenth aspect of the present invention, the strain measuring apparatus is configured using the wavelength tunable light source according to any one of the seventh, ninth and thirteenth aspects described above. In addition, mode-hop-free and low-coherent light enables stable measurement of distortion fluctuations applied to the fiber Bragg grating in a state with few ripples, and is associated with the wavelength of the output light of the tunable light source. Can be measured.

  Embodiments of the present invention will be described below.

[First Embodiment]
The configuration of the wavelength tunable light source according to the first embodiment of the present invention is shown in FIG. The same elements as those of the conventional wavelength variable light source are denoted by the same reference numerals, and detailed description thereof is omitted. This wavelength tunable light source converts light emitted from the AR-coated end face of the LD 1 and passed through the optical fiber 6 into collimated light by the collimating lens 2 and enters the diffraction grating 3, and the diffraction grating with respect to the incident light. The diffracted light emitted from 3 is incident on the mirror 4 supported so that the angle can be adjusted by the angle adjusting means 5, the reflected light reflected by the mirror 4 is incident on the diffraction grating 3, and the diffracted light with respect to the reflected light is The light is returned from the diffraction grating 3 to the LD 1 through the collimating lens 2 and the optical fiber 6. Further, the 0th-order light of the diffraction grating 3 is incident on an optical resonator 7 such as an etalon, transmits only light of a predetermined wavelength, and the transmitted light is converted into an electric signal b by a light receiver (PD) 8 to be processed. 9 is output. In the processing means 9, the electric signal b having the wavelength information of the output light and the signal a (output) generated by itself to change the angle of the reflecting surface of the mirror 4 output from the angle adjusting means 5. As shown in FIG. 18, the relationship between the oscillation wavelength and the time for varying the wavelength (angle) (which can be said to be the sweep time) is calculated based on the signal that determines the wavelength range. ing.

  In the wavelength tunable light source configured in this way, the resonator length is increased to, for example, several m by the optical fiber 6 to reduce the external resonance mode interval Δλ, and as shown in FIG. Multi-mode oscillation (single-mode oscillation in the prior art) was performed by increasing the number of external resonance modes in the band to about 1000 times that of the conventional resonator length of about several millimeters. Thereby, since the wavelength change due to the mode hop is about several tens of MHz in frequency, which is sufficiently smaller than the conventional several GHz, it is possible to make the mode hop free. In addition, because of the multimode oscillation, it is not necessary to change the diffraction wavelength characteristic and the external resonance mode at the same time as in the prior art because the resonance wavelength (wavelength of the output light) can be changed. The concept of the predetermined position P that determines the rotation axis of the mirror 4, which was a conventional problem, is eliminated. Further, low-coherent light is output by multimode oscillation, and it is possible to improve the superposition of ripple due to reflection when measuring the wavelength characteristics of optical components, which is a drawback of conventional high-coherent light. Note that the half-value widths of the oscillation spectra of the high coherent light and the low coherent light are, for example, several hundred kHz and several GHz, respectively.

  In the wavelength tunable light source of FIG. 1 described above, the light emitted from the end surface of the LD 1 that is not AR-coated is used as the output light. However, when the 0th-order light from the diffraction grating 3 is used as the output light. As shown in FIG. 2, the zero-order light from the diffraction grating 3 is branched by an optical branching means 16 such as an optical coupler, one of which is output light, and the other is incident on the optical resonator 7. When the 0th-order light is output light in this way, the intensity fluctuation of the output light caused by the influence of the internal resonance mode of the LD1 is compared with the case where the light emitted from the end surface of the LD1 that is not AR-coated is output light. Can be small. Specifically, the intensity fluctuation (about 1 dB) when LD1 is used as output light can be reduced to about 1/10. In addition, by applying HR coating (HR: High-Reflection) to the end surface of the LD 1 that is not AR-coated, the intensity of the output light when the 0th-order light is output light can be increased.

[Second Embodiment]
The configuration of the wavelength tunable light source according to the second embodiment of the present invention is shown in FIG. In the first embodiment shown in FIG. 1, the optical fiber 6 is provided between the LD 1 and the collimating lens 2 so that the resonator length is increased to, for example, several meters, so that multimode oscillation is performed. In the case of the embodiment, as shown in FIG. 3, a spatial propagation path 17 having an optical path length of 15 cm or more is provided between the collimating lens 2 and the diffraction grating 3, thereby increasing the resonator length and causing multimode oscillation. I am doing so. This is the only difference from the first embodiment shown in FIG. Therefore, detailed description is omitted.

  FIG. 4 shows an embodiment of a wavelength tunable light source in the case where the above-described spatial propagation path 17 includes a corner cube 17a. The corner cube 17 a emits the collimated light incident from the collimating lens 2 to the diffraction grating 3 while reversing the traveling direction. In this way, by folding back the optical path from the collimating lens 2 to the diffraction grating 3, that is, the spatial propagation path 17, the optical path length, for example, 15 cm can be reduced to about ½, and the apparatus can be downsized. The means for turning back the space propagation path 17 may be a simple mirror in addition to the corner cube.

  In the wavelength variable light source of FIGS. 3 and 4 described above, the light emitted from the end surface of the LD 1 that is not AR-coated is used as the output light. However, the zero-order light of the diffraction grating 3 is used as the output light. In this case, as shown in FIGS. 5 and 6, the zero-order light from the diffraction grating 3 is branched by the optical branching means 16 such as an optical coupler, and one is used as output light and the other is supplied to the optical resonator 7. Incident. When the 0th-order light is output light in this way, the intensity fluctuation of the output light caused by the influence of the internal resonance mode of the LD1 is compared with the case where the light emitted from the end surface of the LD1 that is not AR-coated is output light. Can be small. Specifically, the intensity fluctuation (about 1 dB) when LD1 is used as output light can be reduced to about 1/10. In addition, by applying HR coating (HR: High-Reflection) to the end surface of the LD 1 that is not AR-coated, the intensity of the output light when the 0th-order light is output light can be increased.

[Third Embodiment]
The configuration of the wavelength tunable light source according to the third embodiment of the present invention is shown in FIG. The third embodiment is different from the first embodiment shown in FIG. 1 in that the mirror 4 and the angle adjusting means 5 in FIG. 1 are composed of the MEMS scanner 60 (the reflector 35 and the reflector driving means 50 in FIG. 7). ) Is different only in the point. Therefore, description of the same part as FIG. 1 is omitted, and the MEMS scanner 60 will be mainly described.

  The MEMS scanner 60 includes a reflector 35 and reflector drive means 50, and the diffracted light with respect to the collimated light incident from the diffraction grating 3 is reflected by the reflection surface of the reflector 35 to the diffraction grating 3, and again the diffraction grating. When the diffracted light diffracted by 3 is incident on the LD 1 via the collimator lens 2 and the optical fiber 6, the reflector 35 so that the diffracted light incident on the LD 1 becomes light of a desired wavelength. The angle of the reflecting surface is changed by the reflector driving means 50. Note that a MEMS (Micro Electro Mechanical Systems) scanner means a scanner formed by a micro electro mechanical structure (a structure that operates mechanically under the control of an electrical signal).

As shown in FIG. 9, the reflector 35 includes a pair of fixed substrates 36 and 37 arranged in parallel with each other in a horizontally long rectangle, and the fixed substrate from the center of the long side edge of the pair of fixed substrates 36 and 37. A pair of shaft portions 38 and 39 that extend in a direction perpendicular to 36 and 37 with a predetermined width and length and can be twisted and deformed along the length direction, and one of the long side edges of the horizontally long rectangle. The reflector 40 is connected to the tip of the shaft portion 38 at the center and connected to the tip of the shaft 39 at the center of the other long side edge. Since the central portion of the reflector 40 is supported by the shaft portions 38 and 39 that can be torsionally deformed, the reflector 40 can rotate with respect to the fixed substrates 36 and 37 with the line connecting the shaft portions 38 and 39 as the central axis. it can. Further, the natural frequency f ₀ of the portion composed of the shaft portions 38 and 39 and the reflecting plate 40 is determined by the shape and mass of the reflecting plate 40 itself and the spring constant of the shaft portions 38 and 39.

  A reflective surface 41 for reflecting light is formed on one surface side of the reflective plate 40. The reflection surface 41 may be formed by mirror-finishing the reflection plate 40 itself, or may be formed by vapor deposition or adhesion of a highly reflective film (not shown). The reflector 35 is integrally cut out from a thin semiconductor substrate by etching or the like, and has high conductivity by metal film vapor deposition.

  The support substrate 45 is made of an insulating material, and support bases 45a and 45b projecting forward are formed on the upper and lower portions on one side, and the fixed substrates 36 and 37 of the reflector 35 are formed on the upper and lower sides. Are fixed in contact with the support bases 45a and 45b. In addition, electrode plates 46 and 47 that are opposed to both ends of the reflection plate 40 of the reflector 35 are formed in patterns at both ends of the central portion on the one surface side of the support substrate 45. The electrode plates 46 and 47 constitute a reflector driving means 50 (see FIG. 7) together with a drive signal generator 55 described later, and electrostatic force is alternately and periodically applied to both ends of the reflector plate 40. Then, the reflecting plate 40 is reciprocally rotated around the line connecting the shaft portions 38 and 39. The rotation axis of the reflecting plate 40 is set to be parallel to the diffraction grooves of the diffraction grating 3. The reflector 35 configured as described above receives the diffracted light from the diffraction grating 3 by the reflection surface 41 of the reflection plate 40, makes the reflected light incident on the diffraction grating 3, and diffracts it again.

On the other hand, the drive signal generator 55 constituting a part of the reflector driving means 50 (see FIG. 7) is an electrode plate with reference to the potential of the reflector 35 as shown in FIGS. 10 (a) and 10 (b). applied to 46 and 47, has a frequency corresponding to the natural frequency f ₀ (or a frequency corresponding to the frequency in the vicinity of the natural frequency f _0), the drive signal Da whose phases are shifted from each other by 180 °, the Db Then, an electrostatic force (attraction) is alternately and periodically applied between the electrode plate 46 and one end side of the reflection plate 40 and between the electrode plate 47 and the other end side of the reflection plate 40. Is rotated back and forth within a predetermined angular range at the natural frequency f ₀ or a frequency in the vicinity thereof. The drive signal generator 55 is a signal corresponding to an angle range for reciprocating rotation, that is, a signal a for changing the angle of the reflecting surface 41 by a predetermined range (a signal for determining an output wavelength range, so a sweep signal a Is output to the processing means 9 (see FIG. 7). FIG. 10 shows a case where the two drive signals Da and Db are rectangular waves with a duty ratio of 50%, but the duty ratio of both signals may be 50% or less, and the waveform is also a rectangular wave. It is not limited to sine waves, triangular waves, and the like.

In the MEMS scanner 60 in the wavelength tunable light source according to the third embodiment configured as described above, the reflector 35 is extended from the pair of fixed substrates 36 and 37 and a predetermined length from the edge thereof with a predetermined width, and the length of the reflector 35 is increased. The shaft portions 38 and 39 that can be twisted and deformed along the vertical direction are connected to the ends of the shaft portions 38 and 39 at their edges, and are formed in a symmetrical shape with respect to the shaft portions 38 and 39, The reflection plate 40 is formed by a reflection signal 40 having a frequency corresponding to the natural frequency f ₀ of the portion formed by the shaft portions 38 and 39 of the reflector 35 and the reflection plate 40. Thus, the reflector 40 is reciprocally rotated at the natural frequency f ₀ or in the vicinity thereof.

For this reason, the reflector 40 can be reciprocally rotated at a high speed with a small amount of electrical energy, and the center of rotation is inside the reflector 40 (in this case, the central portion). The amount of change in the reflection angle of the incident light on can be increased. The spring constants of the shaft portions 38 and 39 are determined by the length, width, thickness, and material of the shaft portions 38 and 39, and the natural frequency f ₀ depends on the spring constant and the shape, thickness, material, and the like of the reflector 40. By selecting these parameters, the natural frequency f ₀ can be set within a range of several hundreds of Hz to several tens of kHz.

  Therefore, the wavelength tunable light source according to the third embodiment of the present invention is configured using such a MEMS scanner 60 (consisting of the reflector 35 and the reflector driving means 50), so that the wavelength tunable high-speed light source is high. (Maximum number of 10 kHz) and downsizing of the apparatus can be achieved.

  In the description of FIG. 9 described above, the reflector 35 is made of a material having high conductivity. However, when the reflector 35 is made of a material having low conductivity, the reflecting surface 41 of the reflector 40 Electrode plates facing the electrode plates 46 and 47 are provided on both sides (or the entire surface) of the opposite surface, and electrode plates are also provided on the back side of the fixed substrates 36 and 37, and the electrode plates are connected by a pattern or the like. . Then, the electrode plate that contacts the electrode plates on the back side of the fixed substrates 36 and 37 is formed on the surface of the support bases 45a and 45b of the support substrate 45, and at least one of them is used as a reference potential line to generate the drive signal described above. What is necessary is just to connect to the device 55.

  Further, the fixed substrates may be formed in a U-shaped frame or a rectangular frame shape by connecting one end side or both ends of the fixed substrates 36 and 37. Moreover, the shape of the reflecting plate 40 is also arbitrary, and may be a circle, an ellipse, an oval, a rhombus, a square, a polygon, or the like in addition to the above-described horizontally long rectangle. Further, in order to reduce air resistance during high-speed reciprocating rotation, a large hole or a large number of small holes may be provided inside the reflecting plate 40.

  Further, in the description of FIG. 9 described above, the two electrode plates 46 and 47 facing each other at both ends of the reflection plate 40 of the reflector 35 are provided. However, only one electrode plate (for example, the electrode plate 46) is used for static electricity. Electric power may be applied. Moreover, also about a drive system, you may rotate the reflecting plate 40 reciprocatingly with an electromagnetic force other than the above-mentioned electrostatic force. In this case, for example, a coil is used in place of the electrode plates 46 and 47 described above, a magnetic material or a coil is provided at both ends of the reflection plate 40, and an attractive force due to a magnetic field generated between the coils or between the coil and the magnetic material. The reflector 40 is reciprocally rotated by the repulsive force.

In addition to the above-described method of directly applying the electrostatic force or electromagnetic force to the reflector 40, the above-described natural frequency f ₀ or a vibration in the vicinity thereof is applied to the entire reflector 35 by an ultrasonic vibrator or the like, and the vibration It is also possible to transmit the light to the reflecting plate 40 for reciprocal rotation. In this case, the vibration can be efficiently transmitted to the reflection plate 40 by providing the vibrator on the back side of the support substrate 45 and the support bases 45a and 45b.

  In the wavelength variable light source of FIG. 7 described above, the light emitted from the end surface of the LD 1 that is not AR-coated is used as the output light. However, when the 0th-order light from the diffraction grating 3 is used as the output light. As shown in FIG. 8, the zero-order light from the diffraction grating 3 is branched by an optical branching means 16 such as an optical coupler, and one is made output light and the other is made incident on the optical resonator 7. When the 0th-order light is output light in this way, the intensity fluctuation of the output light caused by the influence of the internal resonance mode of the LD1 is compared with the case where the light emitted from the end surface of the LD1 that is not AR-coated is output light. Can be small. Specifically, the intensity fluctuation (about 1 dB) when LD1 is used as output light can be reduced to about 1/10. In addition, by applying HR coating (HR: High-Reflection) to the end surface of the LD 1 that is not AR-coated, the intensity of the output light when the 0th-order light is output light can be increased.

[Fourth Embodiment]
FIG. 11 shows the configuration of a wavelength tunable light source according to the fourth embodiment of the present invention. In the third embodiment shown in FIG. 7, the optical fiber 6 is provided between the LD 1 and the collimating lens 2 so that the resonator length is increased to, for example, several meters, so that multimode oscillation is performed. In the case of the embodiment, as shown in FIG. 11, a spatial propagation path 17 having an optical path length of 15 cm or more is provided between the collimating lens 2 and the diffraction grating 3, thereby increasing the resonator length and causing multimode oscillation. I am doing so. This is the only difference from the third embodiment shown in FIG. Therefore, detailed description is omitted.

  Moreover, FIG. 12 shows an embodiment of a wavelength tunable light source in the case where the above-described spatial propagation path 17 includes a corner cube 17a. The corner cube 17 a emits the collimated light incident from the collimating lens 2 to the diffraction grating 3 while reversing the traveling direction. In this way, by folding back the optical path from the collimating lens 2 to the diffraction grating 3, that is, the spatial propagation path 17, the optical path length, for example, 15 cm can be reduced to about ½, and the apparatus can be downsized. The means for turning back the space propagation path 17 may be a simple mirror in addition to the corner cube.

  In the wavelength variable light source of FIGS. 11 and 12 described above, the light emitted from the end surface of the LD 1 that is not AR-coated is used as the output light. However, the 0th-order light of the diffraction grating 3 is used as the output light. In this case, as shown in FIGS. 13 and 14, the zero-order light from the diffraction grating 3 is branched by the optical branching means 16 such as an optical coupler, and one is used as output light and the other is supplied to the optical resonator 7. Incident. When the 0th-order light is output light in this way, the intensity fluctuation of the output light caused by the influence of the internal resonance mode of the LD1 is compared with the case where the light emitted from the end surface of the LD1 that is not AR-coated is output light. Can be small. Specifically, the intensity fluctuation (about 1 dB) when LD1 is used as output light can be reduced to about 1/10. In addition, by applying HR coating (HR: High-Reflection) to the end surface of the LD 1 that is not AR-coated, the intensity of the output light when the 0th-order light is output light can be increased.

[Fifth Embodiment]
FIG. 17 shows the configuration of the strain measuring apparatus according to the fifth embodiment of the present invention. The wavelength tunable light source 100 is the wavelength tunable light source of the first to fourth embodiments described above, and outputs the measurement light that is variably (swept in wavelength) over a predetermined wavelength range to the optical circulator 11. Further, the wavelength tunable light source 100 outputs the above-described sweep signal a and the electrical signal b having the wavelength information of the output light to the processing means 13 described later. The optical circulator 11 receives the measurement light from the wavelength tunable light source 100 through the optical fiber 14 and enters the plurality of FBGs 15a and 15b, and receives the reflected light of the measurement light reflected and returned from the FBGs 15a and 15b. The light is emitted to a light receiver (PD) 12. The light receiver 12 converts the reflected light into an electric signal c and outputs it to the processing means 13.

  The processing means 13 regards the temporal variation of the electric signal c from the light receiver 12 as a variation in wavelength based on the sweep signal a from the wavelength variable light source 100, and as shown in FIG. 19A, each FBG 15a , 15b, the variation in distortion is measured. Further, the processing means 13 processes the electrical signal b having the wavelength information of the output light from the wavelength tunable light source 100, the electrical signal c and the sweep signal a from the above-described light receiver 12, and thereby processes each of the above. Wavelength fluctuations caused by the FBGs 15a and 15b can be captured in association with the wavelength of the measurement light as shown in FIG. In FIG. 17, the reflected light from the FBGs 15a and 15b is incident on the light receiver 12, but the transmitted light of the FBGs 15a and 15b may be incident.

  In the strain measuring apparatus configured as described above, when the wavelength tunable light source 100 is configured by the wavelength tunable light source of the first embodiment and the second embodiment, the mode-hop-free and low coherent light is used. Variations in distortion applied to the FBG can be measured stably and with little ripple, and can be measured in association with the wavelength of the output light of the wavelength tunable light source 100. Further, when the wavelength tunable light source 100 is configured by the wavelength tunable light source of the third embodiment and the fourth embodiment, the fluctuation of distortion applied to the FBG is stabilized by pseudo mode hop-free and low coherent light. In addition, the measurement can be performed in a state where there is little ripple, the measurement can be performed in association with the wavelength of the output light of the wavelength tunable light source 100, and the measurement by the MEMS scanner can be speeded up and the apparatus can be downsized.

The figure which shows the structure of 1st Embodiment of this invention. The figure which shows another structure of 1st Embodiment of this invention. The figure which shows the structure of 2nd Embodiment of this invention. The figure which shows another structure of 2nd Embodiment of this invention. The figure which shows another structure of 2nd Embodiment of this invention. The figure which shows another structure of 2nd Embodiment of this invention. The figure which shows the structure of 3rd Embodiment of this invention. The figure which shows another structure of 3rd Embodiment of this invention. The exploded perspective view for demonstrating the reflector of a MEMS scanner Diagram for explaining drive signals The figure which shows the structure of 4th Embodiment of this invention. The figure which shows another structure of 4th Embodiment of this invention. The figure which shows another structure of 4th Embodiment of this invention. The figure which shows another structure of 4th Embodiment of this invention. Diagram for explaining diffraction wavelength characteristics and external resonance mode Diagram for explaining wavelength characteristics The figure which shows the structure of 5th Embodiment of this invention. Diagram showing the relationship between sweep signal and oscillation wavelength Diagram for explaining strain measurement The figure which shows schematic structure of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser (LD), 2 ... Collimating lens, 3 ... Diffraction grating, 4 ... Mirror, 5 ... Angle adjustment means, 6, 14 ... Optical fiber, 7 ... Optical resonators 8, 12... Light receiver (PD) 9, 13... Processing means, 11 Optical circulators, 15 a, 15 b Fiber Bragg grating (FBG), 16. Optical branching means, 17 ... space propagation path, 17a ... corner cube, 35 ... reflector, 36, 37 ... fixed substrate, 38, 39 ... shaft, 40 ... reflector , 41 ... reflective surface, 45 ... support substrate, 45a, 45b ... support base, 46, 47 ... electrode plate, 50 ... reflector drive means, 55 ... drive signal generator , 60 ... MEMS scanner, 100 ... wavelength tunable light source

Claims (15)

A semiconductor laser (1) in which one laser light emitting end face is AR coated;
A collimating lens (2) for collimating light emitted from the AR-coated end face of the semiconductor laser;
A diffraction grating (3) that receives collimated light emitted from the collimating lens and diffracts the collimated light at an angle corresponding to the wavelength;
A mirror (4) for receiving the diffracted light with respect to the collimated light emitted from the diffraction grating and reflecting it to the diffraction grating;
Reflected light from the mirror is incident on the diffraction grating and diffracted again, and when the diffracted light obtained thereby is incident on the semiconductor laser via the collimator lens, the diffracted light incident on the semiconductor laser. And an angle adjusting means (5) for changing the angle of the mirror so that the light has a desired wavelength, and a resonator length configured between the other laser light emitting end face of the semiconductor laser and the mirror In a tunable light source that oscillates in an external resonance mode based on
The wavelength tunable light source, wherein the resonator length is such a resonator length that light oscillated in an external resonance mode based on the resonator length becomes light by multimode oscillation. A semiconductor laser (1) in which one laser light emitting end face is AR coated;
A collimating lens (2) for collimating light emitted from the AR-coated end face of the semiconductor laser;
A diffraction grating (3) that receives collimated light emitted from the collimating lens and diffracts the collimated light at an angle corresponding to the wavelength;
A diffracted light for the collimated light incident from the diffraction grating is reflected to the diffraction grating by the reflection surface of the reflector, and includes a reflector (35) and a reflector driving means (50). When diffracted light is again diffracted by the diffraction grating and incident on the semiconductor laser through the collimating lens, the diffracted light incident on the semiconductor laser becomes light of a desired wavelength. A MEMS scanner (60) that changes the angle of the reflecting surface of the reflector by the reflector driving means, and is configured between the other laser light emitting end surface of the semiconductor laser and the reflecting surface of the reflector. A tunable light source that oscillates in an external resonance mode based on the resonator length,
The wavelength tunable light source, wherein the resonator length is such a resonator length that light oscillated in an external resonance mode based on the resonator length becomes light by multimode oscillation. The reflector of the MEMS scanner is:
A fixed substrate (36, 37);
Shaft portions (38, 39) that extend from the edge of the fixed substrate with a predetermined width and have a predetermined length and can be twisted and deformed along the length direction;
A reflection plate (40) formed by being connected to the tip of the shaft portion at its edge and provided with the reflection surface for reflecting the diffracted light from the diffraction grating on one surface side; ,And,
The reflector driving means of the MEMS scanner includes:
A force is applied to the reflecting plate by a driving signal having a frequency corresponding to the natural frequency of the portion composed of the shaft portion of the reflector and the reflecting plate, and the reflecting plate is rotated back and forth at the natural frequency or a frequency close thereto. The wavelength tunable light source according to claim 2, wherein the wavelength tunable light source is configured so as to cause the light to oscillate.   The wavelength tunable light source according to any one of claims 1 to 3, further comprising an optical fiber (6) having a predetermined length between the semiconductor laser and the collimating lens.   The wavelength tunable light source according to any one of claims 1 to 3, further comprising a spatial propagation path (17) having an optical path length of 15 cm or more between the collimating lens and the diffraction grating.   6. The wavelength tunable light source according to claim 5, wherein the spatial propagation path includes a corner cube (17a). An optical resonator (7) provided on an optical path through which the zero-order light of the diffraction grating is emitted and transmitting light of a predetermined wavelength;
A first light receiver (8) that receives the transmitted light emitted from the optical resonator and converts the transmitted light into a first electric signal, and the first electric signal output from the first light receiver. The wavelength tunable light source according to any one of claims 1 to 6, wherein the wavelength of the emitted light of the semiconductor laser can be obtained.   The wavelength tunable light source according to claim 1, wherein the 0th-order light of the diffraction grating is output light. A light branching means (16) provided on an optical path from which the 0th-order light of the diffraction grating is emitted, branching the 0th-order light into two and emitting one of the 0th-order lights as the output light;
An optical resonator (7) that receives the other zero-order light emitted from the light branching means and transmits light of a predetermined wavelength;
A first light receiver (8) that receives the transmitted light emitted from the optical resonator and converts the transmitted light into a first electric signal, and the first electric signal output from the first light receiver. The wavelength tunable light source according to claim 8, wherein the wavelength of the emitted light of the semiconductor laser can be obtained from the above. A semiconductor laser (1) in which one laser light emitting end face is AR coated;
A collimating lens (2) for collimating light emitted from the AR-coated end face of the semiconductor laser;
A diffraction grating (3) that receives collimated light emitted from the collimating lens and diffracts the collimated light at an angle corresponding to the wavelength;
A mirror (4) for receiving the diffracted light with respect to the collimated light emitted from the diffraction grating and reflecting it to the diffraction grating;
Reflected light from the mirror is incident on the diffraction grating and diffracted again, and when the diffracted light obtained thereby is incident on the semiconductor laser via the collimator lens, the diffracted light incident on the semiconductor laser. And an angle adjusting means (5) for changing the angle of the mirror so that the light has a desired wavelength, and a resonator length configured between the other laser light emitting end face of the semiconductor laser and the mirror In a tunable light source that oscillates in an external resonance mode based on
Between the semiconductor laser and the collimating lens, there is provided an optical fiber (6) for receiving light emitted from the AR-coated end face of the semiconductor laser and transmitting the light for a predetermined length to enter the collimating lens. A tunable light source characterized by that. A semiconductor laser (1) in which one laser light emitting end face is AR coated;
An optical fiber (6) that receives light emitted from an AR-coated end face of the semiconductor laser and transmits the light for a predetermined length;
A collimating lens (2) for receiving and collimating light emitted from the optical fiber;
A diffraction grating (3) that receives collimated light emitted from the collimating lens and diffracts the collimated light at an angle corresponding to the wavelength;
A diffracted light for the collimated light incident from the diffraction grating is reflected to the diffraction grating by the reflection surface of the reflector, and includes a reflector (35) and a reflector driving means (50). When the diffracted light diffracted by the diffraction grating again enters the semiconductor laser through the collimating lens and the optical fiber, the diffracted light incident on the semiconductor laser is light having a desired wavelength. And a MEMS scanner (60) for changing the angle of the reflecting surface of the reflector by the reflector driving means, and between the other laser light emitting end surface of the semiconductor laser and the reflecting surface of the reflector. A wavelength tunable light source that oscillates in an external resonance mode based on a resonator length constituted by: The reflector of the MEMS scanner is:
A fixed substrate (36, 37);
Shaft portions (38, 39) that extend from the edge of the fixed substrate with a predetermined width and have a predetermined length and can be twisted and deformed along the length direction;
A reflection plate (40) formed by being connected to the tip of the shaft portion at its edge and provided with the reflection surface for reflecting the diffracted light from the diffraction grating on one surface side; ,And,
The reflector driving means of the MEMS scanner includes:
A force is applied to the reflecting plate by a driving signal having a frequency corresponding to the natural frequency of the portion composed of the shaft portion of the reflector and the reflecting plate, and the reflecting plate is rotated back and forth at the natural frequency or a frequency close thereto. The wavelength tunable light source according to claim 11, wherein the wavelength tunable light source is configured so as to cause the light to oscillate. An optical resonator (7) provided on an optical path through which the zero-order light of the diffraction grating is emitted and transmitting light of a predetermined wavelength;
A first light receiver (8) that receives the transmitted light emitted from the optical resonator and converts the transmitted light into a first electric signal, and the first electric signal output from the first light receiver. The wavelength tunable light source according to any one of claims 10 to 12, wherein the wavelength of the emitted light of the semiconductor laser can be obtained from the above. The wavelength tunable light source (100) according to any one of claims 1 to 13, which oscillates light in a predetermined wavelength range and makes the light incident on a fiber Bragg grating (15a, 15b) as measurement light,
A second light receiving device that receives the measurement light incident on the fiber Bragg grating and receives the light reflected by the fiber Bragg grating or the light transmitted through the fiber Bragg grating and converts the light into a second electrical signal ( 12)
Based on the second electric signal output from the second light receiver and the signal for changing the angle of the reflecting surface of the mirror or the reflector output from the wavelength variable light source, the fiber A distortion measuring apparatus using a wavelength tunable light source, comprising processing means (13) for determining a variation in distortion applied to the Bragg grating. The tunable light source (100) according to any one of claims 7, 9 and 13, which oscillates light in a predetermined wavelength range and makes the light incident on a fiber Bragg grating (15a, 15b) as measurement light,
A second light receiving device that receives the measurement light incident on the fiber Bragg grating and receives the light reflected by the fiber Bragg grating or the light transmitted through the fiber Bragg grating and converts the light into a second electrical signal ( 12)
Based on the second electric signal output from the second light receiver and the signal for changing the angle of the reflecting surface of the mirror or the reflector output from the wavelength variable light source, the fiber While calculating | requiring the fluctuation | variation of the distortion added to the Bragg grating, the angle of the reflective surface of the said 1st electric signal output from the said 1st light receiver and the said mirror output from the said wavelength variable light source or the said reflector is obtained. A distortion measuring apparatus using a wavelength tunable light source, comprising processing means (13) for determining a wavelength of the emitted light of the semiconductor laser based on a signal for changing.

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