JP2014207343A - Pulse oscillation fiber laser and electronic apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which, while a CFBG is known as a dispersion compensation element, since a dispersion amount provided by a regular CFBG is too large compared to a dispersion amount generated in a resonator, it is not possible to appropriately compensate a dispersion of a resonator.SOLUTION: By using a dispersion amount of a finite difference obtained by combining CFBGs having different signs of dispersion, a dispersion generated in a resonator is compensated. By integrating a dispersion controlling mechanism, a dispersion amount may be arbitrarily controlled and a desired pulse width may be obtained.

Description

  The present invention relates to a pulsed fiber laser.

Fiber lasers are expected to serve as a light source to replace solid-state lasers because of their high stability and downsizing characteristics, and are increasingly used in measurement and processing applications. Wavelength dependence), and the speed of light propagation varies depending on the wavelength. Dispersion in which light on the short wavelength side advances fast and light on the long wavelength side advances slowly is called anomalous dispersion. Dispersion that advances more slowly on short wavelength light and advances faster on longer wavelength light is called normal dispersion. Since the pulse width spreads when the laser beam propagates through the fiber, dispersion compensation (suppression of the spread of the pulse width) needs to be performed when a short pulse laser is manufactured.

  This dispersion compensation generally uses a diffraction grating [Patent Document 1].

  As a dispersion compensation method, in addition to a method using a diffraction grating pair, CFBG (Chirped Fiber Bragg Grating) can be cited. In particular, a technique for performing dispersion compensation by combining CFBGs having different bands has been developed [Patent Document 2].

JP2009-252824 JP 2010-288200 A

  The method using CFBG has an advantage that it is not necessary to extract light outside like a diffraction grating. However, in order to obtain a high reflectance, a normal CFBG engraves tens of thousands of gratings for one Bragg wavelength. As a result, the optical path length difference for each wavelength becomes large, and the amount of dispersion as a whole of the CFBG becomes too large, which makes it difficult to perform appropriate dispersion compensation.

  An example for solving the above problem is characterized by combining CFBGs having different signs of dispersion and compensating the dispersion of the resonator using the difference dispersion amount.

  According to the present invention, it is possible to provide a pulsed fiber laser that realizes appropriate dispersion compensation by CFBG.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

It is explanatory drawing of the basic composition of a pulse oscillation fiber laser. It is explanatory drawing of the dispersion compensation using a diffraction grating pair. It is explanatory drawing of a prior art. It is explanatory drawing of the structure of CFBG. It is explanatory drawing of the structure of FBG. It is a schematic block diagram of this invention. It is the schematic of the relationship of two CFBG. It is explanatory drawing of a dispersion amount control mechanism. It is explanatory drawing of a dispersion amount control mechanism. It is explanatory drawing of a dispersion amount control mechanism. It is a resonator manufacturing flow.

  A basic configuration of a pulsed fiber laser is shown in FIG. The resonator 1, the frequency modulator 2, the pulse stretcher 3, the amplifier 4, and the pulse compressor 5 are included. The laser beam oscillated from the resonator 1 is modulated to a desired frequency by the frequency modulator 2, and is emitted to the outside through a pulse stretcher 3 that widens the pulse width, an amplifier 4, and a pulse compressor 5 that narrows the pulse width. A fiber doped with Er (Erbium) or Yb (Yterbium) is often used as the pumping source of the resonator 1, and an inversion distribution is formed by introducing pumping light into the doped fiber, and laser is induced by stimulated emission. Oscillates. In light sources in the field of communication and measurement, an Er-doped fiber (EDF: Er Doped Fiber) having an oscillation wavelength near 1550 nm is often used, and a Yb-doped fiber (YDF: Yb Doped Fiber) having a high gain is often used for processing applications. The oscillation wavelength of YDF is around 1030 nm. The laser beam oscillated from the resonator 1 has a high peak value (peak energy) because it oscillates in a pulse, and if it is amplified with a short pulse width, the peak value becomes very high, and a nonlinear effect is produced. If it happens, the fiber may be damaged. Therefore, before the amplifier 4 amplifies the output, the pulse width is widened by the pulse stretcher 3 to reduce the peak value. The output is amplified in a state where the peak value is lowered, and finally the pulse width is narrowed by the pulse compressor 5, thereby increasing the peak value and injecting.

  An optical fiber has dispersion (wavelength dependence of refractive index), and has a feature that the speed of light propagation varies depending on the wavelength. Dispersion in which light on the short wavelength side advances fast and light on the long wavelength side advances slowly is called anomalous dispersion. Dispersion that advances more slowly on short wavelength light and advances faster on longer wavelength light is called normal dispersion. Since the pulse width spreads when the laser beam propagates through the fiber, dispersion compensation (suppression of the spread of the pulse width) needs to be performed when a short pulse laser is manufactured. In the band near 1550 nm, EDF shows normal dispersion, and SMF (Single Mode Fiber) shows anomalous dispersion. Therefore, in a resonator using EDF as an excitation source, the lengths of EDF and SMF are adjusted to appropriate lengths. By doing so, it becomes possible to cancel each other's dispersion and oscillate with a short pulse width. However, in the band near the wavelength of 1030 nm, both YDF and SMF exhibit normal dispersion as an example. Therefore, in a resonator using YDF as an excitation source, dispersion compensation can be performed by adjusting the lengths of YDF and SMF. This is not possible, and the pulse width increases as the laser beam propagates through the fiber (the light on the long wavelength side always advances first). Therefore, it is necessary to incorporate a dispersion compensation mechanism in order to manufacture an ultrashort pulse laser using YDF. In general, a dispersion grating is often used for dispersion compensation.

The dispersion compensation using the diffraction grating pair will be described with reference to FIG. In the diffraction grating, the incident light is diffracted at different angles depending on the wavelength, so that it is possible to give an optical path length difference for each wavelength. When the laser beam 10 is incident on the diffraction grating 11, it is diffracted at different angles for each wavelength. The incident angle of the laser beam on the diffraction grating 11 is θ, the long wavelength component is λ ₁ , and the short wavelength component is λ ₂ . In the configuration of FIG. 2, since the diffraction angle increases as the wavelength increases, the long wavelength component λ ₁ of the laser beam is given a longer optical path length than the short wavelength component λ ₂ . In the Yb-doped fiber laser, since the long wavelength side is preceded, dispersion compensation can be performed by giving the long wavelength component λ ₁ of the laser beam longer than the short wavelength component λ _{2 in} the diffraction grating 11. Light diffracted at different angles for each wavelength is incident on the diffraction grating 12 to be parallel light, and is incident on the mirror 13. The laser beam reflected by the mirror 13 is transmitted through the diffraction grating 12, so that an optical path length as long as the long wavelength component λ ₁ of the laser beam is given again to perform dispersion compensation. When the laser beam is reflected by the mirror 13, the incident angle to the diffraction grating 12 is set to the same angle θ as the incident angle to the diffraction grating 11, thereby returning to the same spot diameter as the original laser beam after passing through the diffraction grating 11. Can do. Since the optical path length difference between the long wavelength component λ ₁ and the short wavelength component λ ₂ of the laser beam can be changed by changing the distance between the diffraction grating pairs, the amount of dispersion compensation corresponding to the amount of dispersion generated in the resonator can be changed. Control becomes possible.

  A Yb-doped fiber laser using a dispersion compensation mechanism will be described with reference to FIG. The laser beam emitted from the excitation LD 20 propagates inside the SMF 21. The laser beam passes through a WDM coupler (WDM: Wavelength Division Multiplexing) 22 and is introduced into the YDF 23 to cause stimulated emission and emit a laser having a center wavelength of 1030 nm. The laser beam is emitted from the collimator 25 to the free space via the branch coupler 24, and is pulsated by the nonlinear polarization rotation controller. The nonlinear polarization rotation controller includes λ / 4 plates 26 and 33, λ / 2 plate 27, and PBS (polarized beam splitter) 28. The nonlinear polarization rotation controller is a mechanism for promoting pulse oscillation by utilizing the fact that the polarization rotation method depends on the intensity. When linearly polarized light propagates through the fiber, it changes to elliptically polarized light due to the asymmetry of the cross-sectional shape of the core. Elliptical polarization rotates due to non-linear effects. At this time, since the polarized light of the strong component rotates more than the weak component, only the pulse wave having the high light intensity passes through the PBS using the λ / 4 plate 26 and the λ / 2 plate 27. By adjusting the polarization state so that components with low light intensity do not pass, pulse oscillation can be promoted. The pulse component of the laser beam passes on the mirror 29 and enters the diffraction gratings 30 and 31, and dispersion compensation is performed. When the light is reflected by the mirror 32, the angle of the mirror 32 is tilted up and down or left and right, so that the laser beam is reflected at different angles, so that incident light and reflected light can be separated. After passing through the diffraction grating, the laser beam is reflected by the mirror 32, and dispersion compensation is performed again by the diffraction gratings 30 and 31. After the dispersion-compensated laser beam is reflected by the mirror 29, it is returned to the same polarization as the pulse component propagating through the fiber by the λ / 4 plate 33, condensed by the collimator 34, and reentered into the fiber. The laser beam that has returned into the resonator is transmitted through the isolator 35 to prevent return light, is combined with the excitation light having a wavelength of 976 nm by the WDM coupler 22, and is emitted from the branch coupler 24 to the outside of the resonator through the YDF 23.

As a dispersion compensation method, there is CFBG (Chirped Fiber Bragg Grating) in addition to a method using a diffraction grating pair (FIG. 4). CFBG is a fiber-type element in which a diffraction grating is formed in the core of an optical fiber to provide a function as an optical filter. FIG. 5 shows a configuration of a normal FBG (Fiber Bragg Grating). FIG. 5 shows the fiber core 40 and the clad 41, and the coating is not shown. A diffraction grating 42b is formed by exposing the core 40 with ultraviolet rays. Wavelength of light reflected by the diffraction grating 42b is called a Bragg wavelength lambda _B, determined by the refractive index of the pitch and the core of the diffraction grating 42b. When light including the same wavelength as the black wavelength λ _B is incident on the diffraction grating 42b, only the light λ _B having the same wavelength as the Bragg wavelength is reflected by the diffraction grating 42b, and wavelengths other than the black wavelength λ _B are reflected on the diffraction grating 42b. To Penetrate. The Bragg λ _B wavelength becomes longer as the pitch of the diffraction grating is wider, and becomes longer as the refractive index of the core is larger. On the other hand, the CFBG changes the period of the diffraction grating 42a in the fiber according to the position of the fiber. Thereby, the wavelength reflected can be changed according to the position of the fiber. For example, as shown in FIG. 4, the pitch of the diffraction grating near the incident position of the laser beam is narrowed, and the pitch of the diffraction grating is increased as the distance from the incident position is increased. When the wavelength on the short wavelength side of the laser beam is λ _B1 and the wavelength on the long wavelength side is λ _B2 , the laser beam incident on the CFBG is reflected by the light having the Bragg wavelength λ _B1 at the diffraction grating near the incident position. The light having the Bragg wavelength λ _B2 is reflected by the diffraction grating far from the center. As a result, it is possible to produce a CFBG in which light on the long wavelength side is given a longer optical path length than light on the short wavelength side. This corresponds to giving anomalous dispersion.

  Based on the above description, a pulse oscillation fiber laser using CFBG will be described in detail in the following examples.

In this embodiment, an example will be described in which dispersion compensation is performed using a dispersion amount of a difference between CFBGs having different dispersion codes.

FIG. 6 shows a configuration diagram of the resonator of this embodiment.
The excitation laser emitted from the excitation LD 20 propagates through the SMF 21. The center wavelength of the excitation LD 20 is, for example, 976 nm. After passing through the WDM 22, the excitation laser is introduced into the YDF 23 that is an oscillation medium, and stimulates and emits a laser beam having a wavelength of 1030 nm. The laser beam passes through the branch coupler 24 and pulsates in the saturable absorber 45. The saturable absorber operates as an absorber for incident light having a low intensity, and the ability as an absorber is saturated for incident light having a high intensity, and operates as a transparent body. As a result, the oscillated laser beam is made incident on the saturable absorber, so that the continuous wave component having a low intensity is absorbed and the pulse oscillation is promoted. The pulsed laser beam is compensated for dispersion by the dispersion compensation mechanism 51. The dispersion compensation mechanism 51 includes circulators 46 and 48, CFBGs 47 and 49, and a dispersion amount control mechanism 50. The optical path of the laser beam is changed by the circulator 46 and enters the CFBG 47. The CFBG 47 increases the pitch of the diffraction grating as it is closer to the circulator 46, and narrows the pitch of the diffraction grating as it is farther from the circulator 46, so that the optical path length becomes shorter toward the longer wavelength side and normal dispersion can be given. The laser beam reflected by the CFBG 47 changes its optical path by the circulators 46 and 48 and enters the CFBG 49. The closer the CFBG 49 is to the circulator 48, the narrower the pitch of the diffraction grating, and the farther away from the circulator 48, the wider the pitch of the diffraction grating, so that the shorter the wavelength, the shorter the optical path length and the extraordinary dispersion. As a result, the laser beam before being incident on the CFBG 47 and the laser beam after being reflected by the CFBG 49 are given dispersion by the difference amount of the difference between the CFBG 47 and the CFBG 49.

  Here, when the relationship between the CFBGs 47 and 49 is schematically shown, the fine pitch directions are in conflict with each other as shown in FIG.

  For example, the dispersion parameter of CFBG 47 is -50 ps / nm, and the dispersion parameter of CFBG 49 is 55 ps / nm. The laser beam incident on the CFBG 47 is given a normal dispersion of −50 ps / nm, and pulse stretching occurs. Thereafter, pulse compression occurs by providing anomalous dispersion of 55 ps / nm with CFBG49. As a result, before the CFBG 47 is incident and after the CFBG 49 is incident, the laser beam is given an anomalous dispersion of 5 ps / nm, which is a dispersion amount of the difference between the two CFBGs. When the spectral width of the laser beam before the CFBG 47 incidence is 5 nm and the pulse width is 26 ps, if an anomalous dispersion of 5 ps / nm is given, the pulse width is compressed to 1 ps after the CFBG 49 is incident. Thus, by using the dispersion amount of the difference of the CFBG, it is possible to realize a dispersion amount smaller than the dispersion parameter of the CFBG alone, and it is possible to appropriately compensate for the dispersion generated in the resonator. The laser beam reflected by the CFBG 49 is changed in its optical path by the circulator 48, passes through the isolator 35, and suppresses damage to the element due to return light. The laser beam is combined with an excitation laser having a wavelength of 976 nm by the WDM coupler 22 and then emitted from the branch coupler 24 to the outside of the resonator through the YDF 23. After the laser beam is emitted, the autocorrelator 52 measures the pulse width to check whether a desired pulse width is obtained. When a desired pulse width is not obtained only by the difference dispersion amount between CFBG 47 and CFBG 49, the dispersion amount control mechanism 50 adjusts the dispersion compensation amount. The dispersion compensation amount to be adjusted is calculated from the pulse width measured by the autocorrelator 52 and the target pulse width. A control amount in the dispersion amount control mechanism 50 is calculated from the calculated dispersion compensation amount, and is fed back to the dispersion amount control mechanism 50 to adjust the dispersion compensation amount. The calculation of the dispersion amount controlled by the dispersion amount control mechanism may be performed either manually or automatically. For example, when the measurement result is a spectrum width of 5 nm, a pulse width of 1 ps, and a target pulse width of 500 fs, the dispersion amount control mechanism 50 gives a dispersion of 0.1 ps / nm, thereby changing the pulse width from 1 ps to 500 fs. It becomes compressible. The amount of adjustment of dispersion in the dispersion amount control mechanism 50 is stored in a database in advance, and an arbitrary amount of adjustment can be realized by feeding back experimental results.

  In this embodiment, CFBGs are continuously arranged, but it is not necessary to be limited to this.

  In the present embodiment, an example of a dispersion amount control mechanism will be described.

  FIG. 8 illustrates a configuration in which the amount of dispersion is adjusted by applying stress to CFBG. Description of the elements 20 to 24, 35, and 45 to 49 described in FIG. 6 is omitted. The dispersion amount adjusting mechanism includes a rubber plate 62 and motors 63a and 63b. CFBGs 47 and 49 are bonded to a rubber plate. One end of the rubber plate 62 is fixed by a jig, and the other end is connected to the motors 63a and 63b. The motors 63a and 63b apply a stress in the z-axis direction to the rubber plate 62 by controlling the rotational torque, thereby enabling the rubber plate 62 to be bent uniformly. By using a stepping motor as the motor, the bending amount of the rubber plate 62 can be controlled with high accuracy.

  When the rubber plate 62 is bent, the fiber length of one CFBG is increased, so that the pitch of the diffraction grating is increased. Thereby, since the optical path length difference for each wavelength increases, the absolute value of the dispersion amount increases. For example, the length of the CFBG 47 can be increased by 0.1 mm by driving the motor 63a and bending the rubber plate 62 in the positive z-axis direction. As a result, the dispersion amount changes from 50.0 ps / nm to 50.2 ps / nm. In contrast, since the fiber length of the CFBG 49 attached to the other surface of the rubber plate 62 is shortened, the pitch of the diffraction grating is shortened. Thereby, the optical path length difference for each wavelength becomes small, and the absolute value of the dispersion amount becomes small. For example, the amount of dispersion can be changed from −50.5 ps / nm to −50.3 ps / nm by reducing the length of CFBG 49 by 0.1 mm. As a result, the dispersion amount of the difference between the two CFBGs changes from -0.5 ps / nm to -0.1 ps / nm, and the absolute value of the dispersion amount can be reduced. By controlling the dispersion amounts of the CFBGs 47 and 49 at the same time as described above, the dispersion amount can be adjusted with a small control amount. By making a database of changes in the bending amount and dispersion amount of the CFBG in advance and feeding back to the measurement conditions and measurement results, it is possible to adjust to a desired pulse width.

  In the present embodiment, a configuration has been described in which the rubber plate is bent to reduce the CFBG differential dispersion amount. However, a configuration in which the CFBG differential dispersion amount is increased may be used. Thereby, when the dispersion amount of the difference of CFBG is smaller than the dispersion amount generated in the resonator, the dispersion generated in the resonator can be compensated by increasing the dispersion amount of the difference of CFBG.

  In this embodiment, stress is applied to CFBG using a rubber plate, but it is not necessary to be limited to this.

  In this embodiment, the rubber plate is bent using a motor, but the present invention is not limited to this.

  A third embodiment of the present invention will be described with reference to FIG.

  FIG. 9 illustrates a configuration in which the dispersion amount is adjusted by controlling the temperature difference between two CFBGs. When a temperature change is given to CFBG, the Bragg wavelength changes because the refractive index depends on the temperature. Further, since the glass expands and contracts due to a temperature change, the pitch of the diffraction grating changes and the Bragg wavelength changes. Description of the elements 20 to 24, 35, and 45 to 49 described in FIG. 6 is omitted. CFBGs having different signs are attached to both surfaces of the Peltier element 64 to control the temperature difference between the two CFBGs.

  The Peltier element 64 is controlled by a temperature adjustment mechanism 65. The CFBG 47 heated by the Peltier element 64 has a high refractive index. Further, since the fiber length is extended by thermal expansion, the pitch of the diffraction grating is increased. Thereby, the optical path length difference for each wavelength becomes long, and the absolute value of the dispersion amount becomes large. For example, the dispersion amount can be changed from 50.0 ps / nm to 50.2 ps / nm by raising the temperature by 1 ° C. On the other hand, the CFBG 49 cooled by the Peltier element 64 has a small refractive index. Further, since the fiber length is shortened by heat shrinkage, the pitch of the diffraction grating is shortened. Thereby, the optical path length difference for each wavelength is reduced, and the absolute value of the dispersion amount is reduced. For example, the dispersion amount can be changed from −50.5 ps / nm to −50.3 ps / nm by lowering the temperature by 1 ° C. As a result, the amount of CFBG difference dispersion can be reduced from -0.5 ps / nm to -0.1 ps / nm. By this method, it becomes possible to control the amount of dispersion of the difference of CFBG, and a desired pulse width can be obtained. By controlling the dispersion amounts of the CFBGs 47 and 49 at the same time as described above, the dispersion amount can be adjusted with a small control amount. The relationship between the temperature change and the dispersion amount change applied to the CFBG is stored in a database and can be adjusted to a desired pulse width by feeding back to the measurement conditions and measurement results.

  In the present embodiment, a configuration has been described in which the temperature of two CFBGs is controlled by a Peltier element to reduce the amount of CFBG difference dispersion, but a configuration in which the amount of CFBG difference dispersion is increased may be used. Thereby, when the dispersion amount of the difference of CFBG is smaller than the dispersion amount generated in the resonator, the dispersion generated in the resonator can be compensated by increasing the dispersion amount of the difference of CFBG.

  In this embodiment, the temperature of the CFBG is controlled using a Peltier element, but it is not necessary to be limited to this.

  Embodiment 4 of the present invention will be described with reference to FIG.

In the present embodiment, an example of a configuration in which a desired dispersion amount is obtained by combining a plurality of CFBGs having different dispersion codes will be described. Description of the elements 20 to 24, 35, and 45 to 49 described in FIG. 6 is omitted. First, the amount of dispersion generated in the resonator is calculated. Then, a combination of CFBGs having the same degree of dispersion as the absolute value of the amount of dispersion generated in the resonator and the sign of dispersion being reversed is selected. For example, when the GVD parameter generated in the resonator is 0.1 ps ² , a combination of a plurality of CFBGs and a dispersion amount of −0.1 ps ² may be selected. Specifically, CFBG dispersion amount CFBG47 is the dispersion of 20.5ps ^2, CFBG49 dispersion amount of -19.8ps ^2, CFBG71 dispersion of 20.0ps ^2, CFBG73 of combination of -20.8Ps ² Is used, the dispersion amount of the entire CFBG becomes −0.1 ps ² , and the dispersion of 0.1 ps ² generated in the resonator can be compensated.

  In this embodiment, a configuration in which four CFBGs are combined is used, but it is not necessary to be limited to this.

  In this embodiment, the CFBG that gives normal dispersion and the CFBG that gives anomalous dispersion are alternately arranged to perform dispersion compensation. However, the present invention is not limited to this.

A manufacturing flow of the fiber laser is shown in FIG. The amount of CFBG dispersion is measured (step 200). The amount of CFBG dispersion is measured using a phase method. The phase method is a method for obtaining a chromatic dispersion value from a difference in arrival times of optical signals at respective wavelengths when passing through a device under measurement using a plurality of light sources having different wavelengths. Each element is fusion-spliced, and manufacture of the resonator is started (step 201). At this time, the length of the fiber used in each element is measured, and the normal dispersion generated in the fiber is calculated (step 202). The dispersion amount to be adjusted by the dispersion amount control mechanism is calculated from the difference amount of the CFBG having different signs and the difference between the dispersions generated in the resonator, and is fed back to the dispersion amount control mechanism to adjust the dispersion amount (step 203). The autocorrelator measures the autocorrelation waveform, determines the sign of the laser beam dispersion, and measures the pulse width (step 204). The autocorrelation waveform shows a different waveform depending on the sign of dispersion. In the normal dispersion region, an autocorrelation waveform having a high peak value called stretch pulse mode synchronization is observed. On the other hand, in the anomalous dispersion region, an autocorrelation waveform of a sech ² function called soliton mode synchronization is observed. It is determined whether desired performance is obtained from the autocorrelation waveform and pulse width (step 205). If the desired performance has not been achieved, the dispersion amount control mechanism is adjusted again to change the dispersion amount. If the desired pulse width is obtained, the fiber laser fabrication is completed (step 206).

  In this example, the amount of CFBG dispersion was measured using the phase method, but the present invention is not limited to this.

  In this embodiment, the dispersion amount of CFBG is measured (step 200), the manufacture of the resonator is started (step 201), and the dispersion amount generated in the resonator is calculated (step 202). There is no need to

DESCRIPTION OF SYMBOLS 1 ... Resonator, 2 ... Frequency modulation part, 3 ... Pulse stretcher, 4 ... Amplifier, 5 ... Pulse compressor, 10 ... Laser beam, 11, 12, 30, 31 ... Diffraction grating, 13, 29, 32 ... Mirror, 20 ... excitation LD, 21 ... SMF, 22 ... WDM coupler, 23 ... YDF, 24 ... branch coupler, 25, 34 ... collimator, 26, 33 ... λ / 4 plate, 27 ... λ / 2 plate, 28 ... PBS, 35 ... Isolator, 40 ... core, 41 ... cladding, 42a ... CFBG diffraction grating, 42b ... FBG diffraction grating, 45 ... saturable absorber, 46, 48, 70, 72 ... circulator, 47, 49, 71, 73 ... CFBG , 50 ... dispersion amount control mechanism, 51 ... dispersion compensation mechanism, 52 ... autocorrelator, 62 ... rubber plate, 63a, 63b ... motor, 64 ... Peltier element, 65 ... Peltier element temperature Degree control mechanism, 200-206 ... fiber laser manufacturing process

Claims (6)

  A pulsed fiber laser comprising: a first CFBG that compensates for dispersion of the fiber laser; and a second CFBG having a different dispersion sign from the first CFBG.   2. The pulsed fiber laser according to claim 1, further comprising a mechanism for controlling a dispersion compensation amount of the first CFBG and the second CFBG.   3. The pulsed fiber laser according to claim 2, wherein a mechanism for controlling a dispersion amount of the first CFBG and the second CFBG by applying stress is incorporated.   3. The fiber laser according to claim 2, wherein a mechanism for controlling a dispersion amount of the first CFBG and the second CFBG by controlling a temperature is incorporated.   2. The pulsed fiber laser according to claim 1, comprising three or more CFBGs, and the dispersion compensation amount is controlled by a difference in dispersion amount of the three or more CFBGs.   An electronic apparatus using the pulsed fiber laser according to claim 1.

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