WO2011027617A1 - パルス幅変換装置および光増幅システム - Google Patents
パルス幅変換装置および光増幅システム Download PDFInfo
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- WO2011027617A1 WO2011027617A1 PCT/JP2010/061627 JP2010061627W WO2011027617A1 WO 2011027617 A1 WO2011027617 A1 WO 2011027617A1 JP 2010061627 W JP2010061627 W JP 2010061627W WO 2011027617 A1 WO2011027617 A1 WO 2011027617A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0057—Temporal shaping, e.g. pulse compression, frequency chirping
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/02—Catoptric systems, e.g. image erecting and reversing system
- G02B17/023—Catoptric systems, e.g. image erecting and reversing system for extending or folding an optical path, e.g. delay lines
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/1086—Beam splitting or combining systems operating by diffraction only
- G02B27/1093—Beam splitting or combining systems operating by diffraction only for use with monochromatic radiation only, e.g. devices for splitting a single laser source
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094049—Guiding of the pump light
- H01S3/094053—Fibre coupled pump, e.g. delivering pump light using a fibre or a fibre bundle
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/17—Multi-pass arrangements, i.e. arrangements to pass light a plurality of times through the same element, e.g. by using an enhancement cavity
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/30—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 grating
- G02F2201/305—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 grating diffraction grating
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2203/00—Function characteristic
- G02F2203/26—Pulse shaping; Apparatus or methods therefor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1106—Mode locking
- H01S3/1112—Passive mode locking
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
- H01S3/16—Solid materials
- H01S3/1601—Solid materials characterised by an active (lasing) ion
- H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
- H01S3/1618—Solid materials characterised by an active (lasing) ion rare earth ytterbium
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
- H01S3/2308—Amplifier arrangements, e.g. MOPA
Definitions
- the present invention relates to a pulse width conversion device that generates an output optical pulse having a pulse width different from the pulse width of an input optical pulse, and an optical amplification system including the optical amplification device and the pulse width conversion device.
- the pulse width of an optical pulse is extended by a pulse width conversion device (pulse extension device) before optical amplification.
- the chirp pulse is used to suppress the instantaneous intensity of the optical pulse within the optical amplifier, and after optical amplification, the pulse width of the optical pulse is compressed by a pulse width conversion device (pulse compression device). It is important to increase (peak value).
- a pulse width conversion device pulse compression device
- a chirp pulse is an optical pulse having the characteristic that the arrival time differs depending on each wavelength component contained in the optical pulse.
- the lower limit of the pulse width of the optical pulse is determined by the bandwidth of the wavelength band constituting the optical pulse. This is called the Fourier limit pulse width.
- the pulse width of the chirp pulse is longer than the Fourier limit pulse width.
- the chirp pulse can be compressed to about the Fourier limit pulse width by passing through a device in which the optical path length of each constituting wavelength component is adjusted to a predetermined length.
- the pulse compression device is generally a device that enables the chirp pulse to be compressed to the Fourier limit pulse width.
- a pulse compression device By placing a pulse compression device at the final stage of the high-intensity ultrashort pulse laser device, the pulse width of the amplified high-energy chirped pulse is compressed and the pulse width is shortened as much as possible to reduce the peak value of the optical pulse. Can be increased.
- Such a pulse compression device can also act as a pulse extension device that extends the pulse width of an optical pulse to form a chirp pulse.
- a pulse width conversion device for converting the pulse width of an optical pulse includes some spectroscopic element as an essential component.
- the spectroscopic element there are mainly those using dispersion inherent to a substance such as a prism, and those using a diffraction effect by an element structure such as a diffraction grating.
- a pulse width conversion device including a prism as a spectroscopic element has a small variable range of the pulse width of an optical pulse, and is difficult to apply to the chirped pulse amplification method. Therefore, a pulse width conversion device having a diffraction grating as a spectroscopic element is widely used.
- FIG. 12 to FIG. 15 are diagrams showing configuration examples of a pulse width conversion device including a diffraction grating as a spectroscopic element.
- the pulse width conversion device 2A shown in FIG. 12 includes four reflective diffraction gratings 31-34.
- the input light pulse Pi is diffracted by the reflection type diffraction grating 31 and dispersed, is diffracted by the reflection type diffraction grating 32 to be a parallel light beam, and is diffracted by the reflection type diffraction grating 33 and converged. Then, it is diffracted by the reflection type diffraction grating 34 and combined to be output as an output light pulse Po.
- the pulse width conversion device 2B shown in FIG. 13 includes four transmission diffraction gratings 21 to 24.
- the input light pulse Pi is diffracted by the transmissive diffraction grating 21 and dispersed, and is diffracted by the transmissive diffraction grating 22 to become a parallel light beam, and is diffracted by the transmissive diffraction grating 23 and converged. Then, it is diffracted by the transmissive diffraction grating 24 and combined to be output as an output light pulse Po.
- a configuration of a pulse width conversion device 2A including four reflective diffraction gratings 31 to 34 as shown in FIG. 12 has been mainly used.
- a transmissive diffraction grating has a thermal advantage due to less light absorption and a price advantage due to the manufacturing process. Yes. Therefore, in recent years, the configuration of the pulse width conversion device 2B including the four transmission diffraction gratings 21 to 24 as shown in FIG. 13 has been used.
- FIGS. 14 and 15 there is also a configuration of pulse width conversion devices 2C and 2D having two transmission diffraction gratings.
- the pulse width conversion device 2C shown in FIG. 14 includes two transmission diffraction gratings 21 and 22.
- the input light pulse Pi is diffracted by the transmissive diffraction grating 21 and dispersed, is diffracted by the transmissive diffraction grating 22 to be a parallel light beam, and the optical path is folded by the right-angle prism 40.
- the optical pulse whose optical path is folded by the right-angle prism 40 is diffracted and converged by the transmissive diffraction grating 22, diffracted by the transmissive diffraction grating 21, and combined to be output as an output optical pulse Po.
- the pulse width conversion device 2D shown in FIG. 15 also includes two transmissive diffraction gratings 21 and 22.
- the input light pulse Pi is diffracted and split by the transmission diffraction grating 21, sequentially reflected by the reflecting mirrors 41 and 42, and diffracted by the transmission diffraction grating 22 to be a parallel light beam.
- the optical path is folded by the right-angle prism 40.
- the optical pulse whose optical path is turned back by the right-angle prism 40 is diffracted and converged by the transmissive diffraction grating 22, sequentially reflected by the reflecting mirrors 42 and 41, diffracted by the transmissive diffraction grating 21, and combined to be output light. It is output as a pulse Po.
- the direction in which the grating of each diffraction grating extends is a direction perpendicular to the paper surface, and the light pulse travels parallel to the paper surface except when the optical path is turned back by the right-angle prism 40.
- the right-angle prism 40 sequentially reflects the optical pulse by the two reflecting surfaces, thereby translating the optical path of the return optical pulse in the direction perpendicular to the paper surface with respect to the optical path of the forward optical pulse.
- the pulse width conversion device requires multiple times of light pulse incidence to the spectroscopic element.
- the number of light pulses incident on the spectroscopic element is four in the smallest case.
- the pulse width conversion devices 2C and 2D shown in FIGS. 14 and 15 are configured to make the optical pulse incident twice on each diffraction grating. The number of diffraction gratings has been reduced.
- the pulse width conversion device 2D shown in FIG. 15 can also be configured using a single long diffraction grating in which the diffraction gratings 21 and 22 are integrated.
- the configuration of the pulse width conversion apparatus as described above requires at least two diffraction gratings or one long diffraction grating.
- the configuration of the pulse width conversion device 2D shown in FIG. 15 if a long diffraction grating is used, only one diffraction grating is required.
- the geometry between the input light pulse Pi and the output light pulse Po and the right-angle prism 40 is not limited. Due to general interference, it is difficult to reduce the size. In particular, this problem becomes significant when a diffraction grating having a large diffraction angle is used.
- the present invention has been made to solve the above problems, and an object of the present invention is to provide a pulse width conversion device that can be easily miniaturized. It is another object of the present invention to provide an optical amplification system that includes such a pulse width conversion device and can be easily miniaturized.
- a pulse width conversion device is a pulse width conversion device that generates an output light pulse having a pulse width different from the pulse width of an input light pulse, and (1) an input light pulse input along a first optical path. Is output along the second optical path at an emission angle corresponding to the wavelength, and a light beam input at an incident angle corresponding to the wavelength along the third optical path is output at a constant emission angle along the fourth optical path. The light beam input at a constant incident angle along the fifth optical path is output at the output angle according to the wavelength along the sixth optical path, and the light beam input at the incident angle according to the wavelength along the seventh optical path is combined.
- a light beam output from the spectroscopic element along the second optical path at an emission angle according to the wavelength is output to the spectroscopic element as a third optical path.
- a first optical system that is input at an incident angle corresponding to the wavelength along (3) the spectral element A second optical system for inputting a light beam output at a constant emission angle along the fourth optical path from the optical element to the spectroscopic element at a constant incident angle along the fifth optical path; and (4) from the spectroscopic element to the sixth optical path.
- a third optical system for inputting the light beam output at the emission angle according to the wavelength along the seventh optical path to the spectroscopic element at the incident angle according to the wavelength.
- the pulse width conversion device is configured such that the incident / exit direction by the combination of the third optical path and the fourth optical path is different from the incident / exit direction by the combination of the first optical path and the second optical path with respect to the incident / exit direction of the light flux in the spectroscopic element.
- An optical amplification system includes (1) an optical amplification device that optically amplifies an optical pulse, and (2) an optical pulse that is optically amplified by the optical amplification device, and compensates for dispersion of the input optical pulse. And a pulse width converter configured as described above for outputting the optical pulse.
- the pulse width conversion device or the optical amplification system according to the present invention can be easily downsized.
- FIG. 1 is a diagram conceptually showing the configuration of a pulse width conversion apparatus 1 according to this embodiment.
- FIG. 2 is a diagram showing a configuration of the pulse width conversion device 1A.
- FIG. 3 is a diagram for explaining the spectral action of the transmissive diffraction grating 20 included in the pulse width conversion device 1A.
- FIG. 4 is a diagram showing a configuration of the pulse width conversion device 1B.
- FIG. 5 is a diagram showing a configuration of the pulse width conversion apparatus 1C.
- FIG. 6 is a diagram illustrating a configuration of the pulse width conversion device 1D.
- FIG. 7 is a diagram showing a configuration of the pulse width conversion device 1E.
- FIG. 8 is a diagram illustrating a configuration of the pulse width conversion device 1F.
- FIG. 1 is a diagram conceptually showing the configuration of a pulse width conversion apparatus 1 according to this embodiment.
- FIG. 2 is a diagram showing a configuration of the pulse width conversion device 1A.
- FIG. 3 is
- FIG. 9 is a diagram illustrating a configuration of the pulse width conversion device 1G.
- FIG. 10 is a diagram for explaining the spectral action of the reflective diffraction grating 30 included in the pulse width converter 1G.
- FIG. 11 is a diagram illustrating a configuration of the optical amplification system 3 according to the present embodiment.
- FIG. 12 is a diagram illustrating a configuration example of a pulse width conversion device including a reflective diffraction grating as a spectroscopic element.
- FIG. 13 is a diagram illustrating a configuration example of a pulse width conversion device including a transmission diffraction grating as a spectroscopic element.
- FIG. 14 is a diagram illustrating a configuration example of a pulse width conversion device including a transmission diffraction grating as a spectroscopic element.
- FIG. 15 is a diagram illustrating a configuration example of a pulse width conversion device including a transmission diffraction grating as a spectroscopic element.
- FIG. 1 is a diagram conceptually showing the configuration of a pulse width conversion apparatus 1 according to the present embodiment.
- the pulse width conversion apparatus 1 includes a spectroscopic element 10, a first optical system 11, a second optical system 12, and a third optical system 13.
- the first optical system 11 and the third optical system 13 may share some or all of the optical components. In FIG. 1, assuming that the first optical system 11 and the third optical system 13 share all the optical components, the first optical system 11 and the third optical system 13 are shown as being common.
- the spectroscopic element 10 can split a light beam input at a constant incident angle for each wavelength and output light of each wavelength component at an emission angle corresponding to the wavelength. In addition, when the light of each wavelength component is input at an incident angle corresponding to the wavelength, the spectroscopic element 10 can output the light of each wavelength component at a constant emission angle.
- the spectroscopic element 10 is, for example, a transmission diffraction grating or a reflection diffraction grating.
- Spectroscopic element 10 outputs an output angle according to the wavelength along a second optical path P 2 by dispersing the input light pulse Pi entered along a first optical path P 1.
- Spectroscopic element 10 outputs a constant output angle of the light beam along a fourth optical path P 4 entered at an incident angle corresponding to the wavelength along the third optical path P 3.
- Spectroscopic element 10 outputs an output angle according to the wavelength along the light beam entered at a certain incident angle along a fifth optical path P 5 to the sixth optical path P 6. Further, the spectroscopic device 10 outputs a light beam having entered at an incident angle corresponding to the wavelength along the seventh optical path P 7 as a multiplexed output light pulse Po along the eighth optical path P 8.
- the spectroscopic element 10 divides the light beam and outputs it along the third optical path P 3 with an emission angle corresponding to the wavelength. can be, also, when the light beam is incident at a certain angle of incidence along the eighth optical path P 8, it is possible to output an output angle according to the wavelength along the seventh optical path P 7 spectrally the light beam .
- the spectroscopic element 10 has the same spectral characteristics when a light beam is input at a constant incident angle along each of the first optical path P 1 , the fourth optical path P 4 , the fifth optical path P 5, and the eighth optical path P 8. .
- the first Optical system 11 the light beam that is output at the output angle according to the wavelength of the spectral element 10 along the second optical path P 2, the incident angle according to the wavelength along the third optical path P 3 to the spectroscopic element 10
- the second optical system 12 a light beam output at a constant output angle from spectroscopic element 10 along the fourth optical path P 4, 5 along the optical path P 5 is input at a constant incident angle to the spectroscopic element 10.
- the third optical system 13 the light beam outputted at the output angle according to the wavelength along the sixth optical path P 6 from the spectral element 10, corresponding to the wavelengths along the seventh optical path P 7 to the spectroscopic element 10 Input at the incident angle.
- Respect incident and exit direction of the light beam in the spectral element 10, input-output direction by the third combination of optical path P 3 and the fourth optical path P 4 is different from the first optical path P 1 and the second input-output direction by the combination of the optical path P 2.
- Respect incident and exit direction of the light beam in the spectral element 10, input-output direction by the combination of the fifth optical path P 5 and the sixth optical path P 6 coincides with the incoming and outgoing direction of the first optical path P 1 and the second combination of optical path P 2 it may be, may be coincident with the incident and exit directions according to the third combination of optical path P 3 and the fourth optical path P 4.
- input-output direction by the combination of the seventh optical path P 7 and the eighth optical path P 8 is the input-output direction by the first optical path P 1 and the second combination of optical path P 2 may coincide, the third may be coincident with the input-output direction by the combination of the optical path P 3 and the fourth optical path P 4, input-output of the fifth optical path P 5 and combinations of the sixth optical path P 6 It may coincide with the direction.
- the incident angle when the light beam along a fifth optical path P 5 to the spectral element 10 is input may be equal to the exit angle when the light beam along a fourth optical path P 4 is output from the spectroscopic element 10.
- a light beam along a third optical path P 3 to the spectroscopic element 10 is input when the light beam along a sixth optical path P 6 is output from the spectroscopic element 10 It is equal to the incident angle of the wavelength component.
- the fourth optical path P 4 and the fifth optical path P 5 are opposite to each other and the third optical path P 3 and the sixth optical path P 6 are opposite to each other with respect to the light incident / exit direction of the light flux in the spectroscopic element 10. In the case of the direction, these optical paths are set so that the light beams do not overlap each other.
- each wavelength when the incident angles of the respective wavelength components the light beam is output along the spectral element 10 to the second optical path P 2 when the light beam along a seventh optical path P 7 to the spectroscopic element 10 is input It may be equal to the emission angle of the component.
- the exit angle at which the output light pulse Po along the eighth optical path P 8 is output from the spectroscopic element 10, when the input light pulse Pi is input along the first optical path P 1 to the spectroscopic element 10 Is equal to the incident angle.
- the input light pulse Pi is input at a constant incident angle along the first optical path P 1 to the spectroscopic element 10. is separated into each wavelength by the spectral element 10.
- the light of each wavelength component dispersed by the spectroscopic element 10 is output from the spectroscopic element 10 along the second optical path P 2 at an emission angle corresponding to the wavelength, and passes through the first optical system 11 to the spectroscopic element 10.
- 3 is entered at an incident angle corresponding to the wavelength along the optical path P 3, are output at a constant output angle from spectroscopic element 10 along the fourth optical path P 4.
- Light of each wavelength component output from the spectroscopic element 10 along the fourth optical path P 4 while a certain output angle is output from a position corresponding to the wavelength of the spectral element 10 are spatially separated ing.
- Light entered at an incident angle corresponding to the wavelength along the seventh optical path P 7 to the spectroscopic element 10 can be combined by the spectroscopic element 10, the output light pulse Po from the spectroscopic element 10 along the eighth optical path P 8 Is output as
- the fifth optical path P 5 , the sixth optical path P 6 , the seventh optical path P 7 and the eighth optical path P 8 are relative to the first optical path P 1 , the second optical path P 2 , the third optical path P 3 and the fourth optical path P 4. May be in the opposite direction.
- Output light pulse Po output from the spectroscopic element 10 along the eighth optical path P 8 is output angle irrespective of the wavelength is constant, the principal rays of the respective wavelength components are matched.
- the pulse width conversion device 1 according to the present embodiment can output an output optical pulse Po by applying second-order or higher-order dispersion in the frequency domain to the input optical pulse Pi. That is, the pulse width conversion device 1 according to the present embodiment can generate the output light pulse Po having a pulse width different from the pulse width of the input light pulse Pi.
- FIG. 2 is a diagram showing a configuration of the pulse width conversion device 1A.
- the pulse width conversion device 1A shown in this figure includes a transmissive diffraction grating 20 as a spectroscopic element 10, a right-angle prism 40 as a component of the second optical system 12, and a first optical system 11 and a third optical system 13. Reflecting mirrors 41 to 43 are provided as respective constituent elements.
- the transmissive diffraction grating 20 splits the light Pi 1 incident from the first side at a constant incident angle, and outputs each wavelength component to the second side at an emission angle corresponding to the wavelength.
- the light Po 1 can be output, and the light Pi 2 incident at a constant incident angle from the second side is dispersed, and light of each wavelength component is emitted to the first side according to the wavelength. Po 2 can be output.
- the transmission type diffraction grating 20 can take a Littrow arrangement in which the incident angle and the outgoing angle (diffraction angle) are equal to each other.
- the direction in which the grating of the transmissive diffraction grating 20 extends is a direction perpendicular to the paper surface, and the light pulse travels parallel to the paper surface except when the optical path is turned by the right-angle prism 40.
- the right-angle prism 40 sequentially reflects the optical pulse by the two reflecting surfaces, thereby translating the optical path of the return optical pulse in the direction perpendicular to the paper surface with respect to the optical path of the forward optical pulse.
- a reflection reducing film is preferably formed on the light incident / exit surface of the right-angle prism 40. The same applies to the drawings described below.
- the input light pulse Pi is input to the transmission diffraction grating 20 at a constant incident angle and is split by the transmission diffraction grating 20 for each wavelength.
- the light of each wavelength component dispersed by the transmissive diffraction grating 20 is output from the transmissive diffraction grating 20 at an emission angle corresponding to the wavelength, and is sequentially reflected by the reflecting mirrors 41, 42, and 43, and then transmitted.
- the light is input to the diffraction grating 20 at an incident angle corresponding to the wavelength, and is output from the transmission diffraction grating 20 at a constant emission angle.
- the light of each wavelength component output from the transmissive diffraction grating 20 is output from a position corresponding to the wavelength on the transmissive diffraction grating 20 and is spatially separated although it has a constant emission angle.
- each wavelength component output from the transmissive diffraction grating 20 at a constant emission angle is folded back by the right-angle prism 40 and input to the transmissive diffraction grating 20 at a constant incident angle.
- Light input to the transmissive diffraction grating 20 at an incident angle corresponding to the wavelength is combined by the transmissive diffraction grating 20 and output from the transmissive diffraction grating 20 as an output light pulse Po.
- the output light pulse Po output from the transmissive diffraction grating 20 has a constant emission angle regardless of the wavelength, and the principal rays of the respective wavelength components coincide.
- the output light pulse Po is obtained by adding second-order or higher-order dispersion in the frequency domain to the input light pulse Pi, and has a pulse width different from the pulse width of the input light pulse Pi.
- Such a pulse width conversion apparatus 1A is suitably used as a pulse compression apparatus that compresses the pulse width of an optical pulse in the final stage of a high-intensity ultrashort pulse laser apparatus.
- the high-intensity ultrashort pulse laser device is configured to optically amplify an optical pulse using the chirp pulse amplification method described above.
- a pulse width conversion device 1A Compressed the pulse width.
- the transmission type diffraction grating 20 has a configuration in which the number of engraved lines is 1370 / mm and light having a wavelength of 1030 nm incident at an incident angle of 45 ° is emitted at a diffraction angle of 45 °.
- the optical path length from the reflecting mirror 41 to the reflecting mirror 43 via the reflecting mirror 42 was set to 30 cm.
- the pulse width of the output optical pulse was 1 ps.
- the pulse width conversion device 1A the pulse width could be actually compressed from 30 ps to 1 ps.
- FIG. 4 is a diagram showing a configuration of the pulse width conversion device 1B.
- the pulse width conversion device 1B shown in this figure includes a transmission diffraction grating 20 as a spectroscopic element 10, a right-angle prism 40 as a component of the second optical system 12, and a first optical system 11 and a third optical system 13.
- a reflecting mirror 41, a right-angle prism 44, and a movable stage 45 are provided as respective constituent elements.
- the pulse width conversion device 1B shown in FIG. 4 is different in that it includes a right-angle prism 44 instead of the reflecting mirrors 42 and 43.
- the difference is that a movable stage 45 is further provided.
- the right-angle prism 44 changes the traveling direction of the light pulse in each of the forward path and the return path by sequentially reflecting the light pulse by the two reflecting surfaces.
- a reflection reducing film is preferably formed on the light incident / exit surface of the right-angle prism 44.
- the movable stage 45 translates the right-angle prism 44 so that the optical path from the light output from the transmissive diffraction grating 20 to the light input to the transmissive diffraction grating 20 in each of the first optical system 11 and the third optical system 13. Acts as an optical path length adjusting section for adjusting the length.
- the output light pulse Po output from the transmissive diffraction grating 20 has a constant emission angle regardless of the wavelength, and the principal rays of the respective wavelength components coincide.
- the output light pulse Po is obtained by adding second-order or higher-order dispersion in the frequency domain to the input light pulse Pi, and has a pulse width different from the pulse width of the input light pulse Pi.
- this pulse width conversion device 1B since the movable stage 45 as an optical path length adjusting unit is provided, the light output from the transmission diffraction grating 20 in each of the first optical system 11 and the third optical system 13 is provided. The optical path length to the light input to the transmissive diffraction grating 20 is adjusted. Thereby, the amount of dispersion in the frequency domain applied to the input light pulse Pi is adjusted, and the amount of compression or expansion of the pulse width of the output light pulse Po with respect to the input light pulse Pi is adjusted.
- FIG. 5 is a diagram showing a configuration of the pulse width conversion device 1C.
- the pulse width conversion device 1C shown in this figure includes a transmissive diffraction grating 20 as a spectroscopic element 10, a right-angle prism 40 as a component of the second optical system 12, and a first optical system 11 and a third optical system 13.
- Reflecting mirrors 41 and 43 and functionalized blocks 46 are provided as the respective constituent elements.
- the pulse width conversion device 1C shown in FIG. 5 is different in that a functional block 46 is provided instead of the reflecting mirror 42.
- the functionalization block 46 inputs light that has reached the incident / exit surface 46a from the reflecting mirror 41, totally reflects the light multiple times on the inner wall surface, and then outputs the light from the incident / exit surface 46b to the reflecting mirror 43. .
- the functionalized block 46 inputs the light that has reached the incident / exit surface 46b from the reflecting mirror 43, totally reflects the light multiple times on the inner wall surface, and then passes from the incident / exit surface 46a to the reflecting mirror 41.
- the functionalized block 46 is preferably made of a material having a high transmittance at the wavelength of input light, and is made of, for example, quartz glass. It is preferable that a reflection reducing film is formed on the incident / exit surfaces 46 a and 46 b of the functionalized block 46.
- the output light pulse Po output from the transmissive diffraction grating 20 has a constant emission angle regardless of the wavelength, and the principal rays of the respective wavelength components coincide.
- the output light pulse Po is obtained by adding second-order or higher-order dispersion in the frequency domain to the input light pulse Pi, and has a pulse width different from the pulse width of the input light pulse Pi.
- the functionalized block 46 is provided in each of the first optical system 11 and the third optical system 13, and thus the first optical system 11 despite a small installation area.
- the optical path length from the light output from the transmissive diffraction grating 20 to the light input to the transmissive diffraction grating 20 can be increased.
- the amount of dispersion in the frequency domain applied to the input light pulse Pi can be increased, and the amount of compression or extension of the pulse width of the output light pulse Po with respect to the input light pulse Pi can be increased.
- the light beam incident on the functionalized block 46 having an installation area of 5 cm ⁇ 4.4 cm circulate about three and a half times by total internal reflection, the light can be emitted after being propagated by a distance of 50 cm. is there.
- FIG. 6 is a diagram showing a configuration of the pulse width conversion device 1D.
- the pulse width conversion device 1D shown in this figure includes a transmission diffraction grating 20 as a spectroscopic element 10, a right-angle prism 40 as a component of the second optical system 12, and a first optical system 11 and a third optical system 13.
- a functionalized block 47 is provided as each component.
- the pulse width conversion device 1D shown in FIG. 6 is different in that a functional block 47 is provided instead of the reflecting mirrors 41 to 43.
- the functionalization block 47 inputs the light reaching the incident / exit surface 47a from the transmissive diffraction grating 20 and totally reflects the light a plurality of times on the inner wall surface, and then transmits the light from the incident / exit surface 47b to the transmissive diffraction grating 47b. 20 output. Further, the functionalization block 47 inputs the light reaching the incident / exit surface 47b from the transmissive diffraction grating 20 and totally reflects the light several times on the inner wall surface, and then transmits the light from the incident / exit surface 47a. Output to the diffraction grating 20.
- the functionalized block 47 is preferably made of a material having a high transmittance at the wavelength of input light, and is made of, for example, quartz glass. It is preferable that a reflection reducing film is formed on the incident / exit surfaces 47 a and 47 b of the functionalized block 47.
- the output light pulse Po output from the transmissive diffraction grating 20 has a constant emission angle regardless of the wavelength, and the principal rays of the respective wavelength components match.
- the output light pulse Po is obtained by adding second-order or higher-order dispersion in the frequency domain to the input light pulse Pi, and has a pulse width different from the pulse width of the input light pulse Pi.
- the functional block 47 is provided in each of the first optical system 11 and the third optical system 13, so that the first optical system 11 despite the small installation area.
- the optical path length from the light output from the transmissive diffraction grating 20 to the light input to the transmissive diffraction grating 20 can be increased.
- the amount of dispersion in the frequency domain applied to the input light pulse Pi can be increased, and the amount of compression or extension of the pulse width of the output light pulse Po with respect to the input light pulse Pi can be increased. .
- the pulse width conversion device 1D can be easily downsized and handled easily because the first optical system 11 and the third optical system 13 are integrated.
- FIG. 7 is a diagram showing a configuration of the pulse width conversion device 1E.
- the pulse width conversion device 1E shown in this figure includes a transmissive diffraction grating 20 as a spectroscopic element 10, a right-angle prism 40 as a component of the second optical system 12, and a first optical system 11 and a third optical system 13.
- a functionalization block 48 is provided as each component.
- the pulse width conversion device 1E shown in FIG. 7 is different in that a functional block 48 is provided instead of the reflecting mirrors 41 to 43.
- the functionalized block 48 is joined to the transmissive diffraction grating 20 by optical contact, and is integrated with the transmissive diffraction grating 20.
- the functionalization block 48 inputs the light output from the transmissive diffraction grating 20 into the interior, totally reflects the light a plurality of times on the inner wall surface, and then outputs the light to the transmissive diffraction grating 20.
- the functionalization block 48 is preferably made of a material having a high transmittance at the wavelength of the input light, for example, quartz glass. When the incident angle of the light beam is equal to or smaller than the total reflection angle upon reflection on the inner wall surface of the functionalized block 48, it is preferable that an appropriate reflection film is formed on the target surface.
- the output light pulse Po output from the transmissive diffraction grating 20 has a constant emission angle regardless of the wavelength, and the principal rays of the respective wavelength components coincide.
- the output light pulse Po is obtained by adding second-order or higher-order dispersion in the frequency domain to the input light pulse Pi, and has a pulse width different from the pulse width of the input light pulse Pi.
- the functional block 48 is provided in each of the first optical system 11 and the third optical system 13, so that the first optical system 11 is small in spite of a small installation area.
- the optical path length from the light output from the transmissive diffraction grating 20 to the light input to the transmissive diffraction grating 20 can be increased.
- the amount of dispersion in the frequency domain applied to the input light pulse Pi can be increased, and the amount of compression or extension of the pulse width of the output light pulse Po with respect to the input light pulse Pi can be increased. .
- the pulse width conversion device 1E can be easily downsized because the spectroscopic element 10 (transmission diffraction grating 20), the first optical system 11 and the third optical system 13 are integrated. It is easy to handle.
- FIG. 8 is a diagram showing a configuration of the pulse width conversion device 1F.
- the pulse width conversion device 1F shown in this figure includes a transmissive diffraction grating 20 as a spectroscopic element 10, a right-angle prism 40 and a prism 49 as components of the second optical system 12, and a first optical system 11 and a third optical system.
- a functional block 48 is provided as a component of each optical system 13.
- the pulse width conversion device 1F shown in FIG. 8 is different in that it further includes a prism 49.
- the prism 49 is joined to the transmissive diffraction grating 20 by optical contact, and is also joined to the right-angle prism 40 by optical contact.
- the prism 49 is preferably made of a material having a high transmittance at the wavelength of input light, for example, quartz glass. Thereby, even if the reflection reducing film on the incident / exit surface of the right-angle prism 40 is omitted, the operation can be suitably performed. However, it is preferable that a reflection reducing film is formed on the input and output surfaces of the input light pulse Pi and the output light pulse Po in the right-angle prism 49.
- the output light pulse Po output from the transmissive diffraction grating 20 has a constant emission angle regardless of the wavelength, and the principal rays of the respective wavelength components match.
- the output light pulse Po is obtained by adding second-order or higher-order dispersion in the frequency domain to the input light pulse Pi, and has a pulse width different from the pulse width of the input light pulse Pi.
- the functional block 48 is provided in each of the first optical system 11 and the third optical system 13, so that the first optical system 11 despite the small installation area.
- the optical path length from the light output from the transmissive diffraction grating 20 to the light input to the transmissive diffraction grating 20 can be increased.
- the amount of dispersion in the frequency domain applied to the input light pulse Pi can be increased, and the amount of compression or extension of the pulse width of the output light pulse Po with respect to the input light pulse Pi can be increased. .
- the pulse width conversion device 1E is miniaturized by integrating the spectroscopic element 10 (transmission diffraction grating 20), the first optical system 11, the second optical system 12, and the third optical system 13. It is easy and easy to handle.
- FIG. 9 is a diagram showing a configuration of the pulse width conversion device 1G.
- the pulse width conversion device 1G shown in this figure includes a reflective diffraction grating 30 as a spectroscopic element 10, a right-angle prism 40 as a component of the second optical system 12, and a first optical system 11 and a third optical system 13. Reflecting mirrors 41 to 43 are provided as respective constituent elements.
- the pulse width conversion device 1G shown in FIG. 9 is different in that a reflection type diffraction grating 30 is provided instead of the transmission type diffraction grating 20.
- the reflective diffraction grating 30 splits the light Pi 1 incident at a constant incident angle from the first side, and outputs each wavelength component to the first side at an emission angle corresponding to the wavelength.
- light Po 1 can output also the light Pi 2 incident at a certain incident angle from the second side (in the direction of incidence and symmetrical relationship of the light Pi 1 with respect to the normal line of the diffraction surface)
- the light Po 2 of each wavelength component can be output to the second side at an emission angle corresponding to the wavelength.
- the center wavelength of light is 1030 nm. It is assumed that the number of engraved lines of the reflective diffraction grating 30 is 1250 / mm.
- the reflection type diffraction grating 30 cannot take a Littrow arrangement in which the incident angle and the outgoing angle (diffraction angle) are equal to each other.
- the input light pulse Pi is input to the reflective diffraction grating 30 at a constant incident angle, and is split by the reflective diffraction grating 30 for each wavelength.
- the light of each wavelength component dispersed by the reflection type diffraction grating 30 is output from the reflection type diffraction grating 30 at an emission angle corresponding to the wavelength, and is sequentially reflected by the reflection mirrors 41, 42, and 43, and then the reflection type.
- the light is input to the diffraction grating 30 at an incident angle corresponding to the wavelength, and is output from the reflective diffraction grating 30 at a constant emission angle.
- the light of each wavelength component output from the reflection type diffraction grating 30 is output from a position corresponding to the wavelength on the reflection type diffraction grating 30 and is spatially separated although it has a constant emission angle.
- each wavelength component output from the reflection type diffraction grating 30 at a constant emission angle is folded back by the right-angle prism 40 and input to the reflection type diffraction grating 30 at a constant incident angle.
- Light input to the reflective diffraction grating 30 at an incident angle corresponding to the wavelength is combined by the reflective diffraction grating 30 and output from the reflective diffraction grating 30 as an output light pulse Po.
- the output light pulse Po output from the reflective diffraction grating 30 has a constant emission angle regardless of the wavelength, and the principal rays of the respective wavelength components coincide.
- the output light pulse Po is obtained by adding second-order or higher-order dispersion in the frequency domain to the input light pulse Pi, and has a pulse width different from the pulse width of the input light pulse Pi.
- An optical amplification system includes an optical amplification device that optically amplifies an optical pulse, a pulse width conversion device that compresses the pulse width of the optical pulse optically amplified by the optical amplification device, and outputs the optical pulse.
- an ultrashort pulse laser light source a MOPA (Master Oscillator Power Amplifier), or the like is also provided with a pulse width conversion device. Since the pulse width conversion devices 1 and 1A to 1G according to the present embodiment can be easily miniaturized, it is useful to use the device as a device that compensates for dispersion of ultrashort pulse laser light. In particular, application to an ultrashort pulse fiber laser device as shown in FIG. 11 is effective.
- FIG. 11 is a diagram showing a configuration of the optical amplification system 3 according to the present embodiment.
- the optical amplification system 3 shown in this figure includes a pump LD 50, an LD light guide fiber 51, an optical coupler 52, a Yb-doped optical fiber 53, a collimator lens 54, a ⁇ / 4 plate 55, a ⁇ / 2 plate 56, and a polarization beam splitter 57.
- a device 1F is provided.
- the optical amplification system 3 oscillates a mode-locked pulse by exciting the Yb-doped optical fiber 53 with the pumping light output from a pumping LD (Laser Diode) 50.
- the front end face of the excitation LD 50 and the LD light guide fiber 51 are optically coupled to each other.
- the LD light guide fiber 51 is 3.2 m in length and has a fiber Bragg grating structure.
- An external resonator is formed by the Bragg grating of the LD light guide fiber 51 and the rear end face of the excitation LD 50, and excitation light having a wavelength of 976 nm corresponding to the period of the Bragg grating is output as a continuous wave at 400 mW.
- This excitation light is supplied to the single-mode Yb-doped optical fiber 53 having a length of 0.8 m through the optical coupler 52 and excites the added Yb ions.
- emitted light is generated in the Yb-doped optical fiber 53.
- This emitted light is emitted from the Yb-doped optical fiber 53, and then extracted to the space as collimated light by the collimating lens 54, converted into a predetermined polarization state by the ⁇ / 4 plate 55 and the ⁇ / 2 plate 56, and polarized.
- the light enters the beam splitter 57.
- a part of the light incident on the polarization beam splitter 57 is reflected by the polarization beam splitter 57 and branched and extracted.
- the light that has passed through the polarization beam splitter 57 and stayed in the optical resonator passes through a Faraday isolator formed by the Faraday rotator 58, the ⁇ / 2 plate 59, and the polarization beam splitter 60, and then is transmitted by the pulse width conversion device 1F. Pulse width is converted.
- the light output after the pulse width is converted by the pulse width conversion device 1F is reflected by the reflecting mirror 61, converted to a predetermined polarization state by the ⁇ / 4 plate 62, condensed by the condenser lens 63, and long.
- the light is incident on a single-mode optical fiber 64 having a length of 1.2 m.
- the light incident on the single mode optical fiber 64 is input to the Yb-doped optical fiber 53 through the optical coupler 52.
- the optical amplification system 3 includes a ring-type optical resonator, causes stimulated emission in the Yb-doped optical fiber 53 in the optical resonator, and generates the stimulated emission light. A part is output from the polarization beam splitter 57 to the outside.
- the optical amplification system 3 according to the present embodiment also includes the pulse width conversion device (particularly the pulse width conversion device 1F) according to the present embodiment in the optical resonator.
- the optical amplification system 3 in order to realize mode-locked oscillation, it is necessary to adjust the dispersion of the laser resonator.
- an element for compensating for such a large dispersion is required.
- all optical materials having high transmittance exhibit positive dispersion. Therefore, when an ultrashort optical pulse having a wavelength of 1300 nm or less is generated by a fiber laser, a specially designed negative dispersion An optical system is required.
- the optical amplification system 3 includes the pulse width conversion device (particularly the pulse width conversion device 1F) according to the present embodiment as a negative dispersion optical system in the optical resonator.
- the pulse width conversion device 1F can be designed using ordinary diffractive optics, and can respond to changes in conditions by changing the size of the functionalized block 48, for example, and can be miniaturized. It is inexpensive and can be easily adjusted for incident light.
- the pulse width conversion device 1F is small enough to fit within a centimeter and the size ratio of the entire optical amplification system 3 does not become a problem.
- the optical amplifying system 3 can emit an optical pulse having a wavelength band of 1010 nm to 1050 nm and a pulse width of 1.3 ps with an average output of 130 mW and a repetition of 40 MHz by a mode lock operation.
- the outgoing light from the polarization beam splitter 57 is a positively chirped pulse, the outgoing light shortened to 50 fs by compressing the pulse width of this outgoing light by the pulse width conversion device according to this embodiment. Can be obtained.
- the pulse width conversion apparatus can achieve the following effects. Compared with the conventional one, the pulse width conversion device according to the present embodiment can reduce the required number of diffraction gratings, and can reduce the size of the diffraction gratings.
- the optical path is folded back by the right-angle prism 40, a large number of portions where the optical path is close and parallel appear, so that the size is reduced due to the geometric interference of the optical element. Difficult to do.
- the adjacent optical paths are not parallel in the pulse width conversion device according to the present embodiment, the geometric interference between the optical element and the mount is alleviated.
- the installation area required for configuring the pulse width conversion device can be reduced. Thereby, a compact arrangement of the pulse width conversion device can be realized.
- the pulse width converter is inevitable to be placed in the final stage of the high-intensity ultrashort pulse laser device in some form. Therefore, the miniaturization of the pulse width conversion device can contribute to the miniaturization of the entire high-intensity ultrashort pulse laser device.
- a mechanism for changing the optical axis length of the dispersed part is required.
- a plurality of incident angles of light to the diffraction grating are used, a plurality of directions of the optical path length changing mechanism can be selected, and the degree of freedom in design is increased.
- the pulse width conversion device may use either a transmissive diffraction grating or a reflective diffraction grating.
- a transmissive diffraction grating when used, the following effects can be achieved. .
- the transmission diffraction grating has a configuration in which the incident angle (angle formed by the incident light and the normal line of the diffraction grating surface) and the diffraction angle (angle formed by the normal line of the diffraction grating surface) are equal to each other ( (Littrow arrangement).
- the reflection type diffraction grating has the optical paths of the incident light and the diffracted light overlapping each other, so that the Littrow arrangement becomes impossible. Therefore, in general, a transmission diffraction grating can be designed to have higher diffraction efficiency than a reflection diffraction grating.
- a transmissive diffraction grating having a diffraction efficiency of 96% can be manufactured for light having a wavelength of 1030 nm.
- the diffraction efficiency of a metal-evaporation type reflection type diffraction grating is about 92%, which is a typical value of a high-quality element on the market.
- the light use efficiency of the entire pulse width conversion device is proportional to the fourth power of the diffraction efficiency. If the 96% and 92% are raised to the fourth power, 85% and 72% are obtained. From this, it can be seen that the configuration using the transmission diffraction grating is more effective.
- a part of the component that is not diffracted (light loss) is absorbed by the metal deposition surface of the diffraction grating, which causes heat generation.
- This heat generation becomes a serious problem when used in a pulse width converter of a high repetition ultrashort pulse laser amplifier having a large average output.
- a reflective diffraction grating that is available at a general price and is normally used has a large thermal effect because the underlying surface of the metal vapor deposition film is made of resin. The thermal influence causes the distortion of the diffraction surface, leading to a decrease in the quality of the laser light, such as a decrease in diffraction efficiency and a wavefront distortion of the diffracted light.
- the transmission diffraction grating suppresses heat generation of the substrate.
- a substrate made of all quartz glass is also available at a low cost, and the distortion of the substrate with respect to heat generation is small.
- Quartz glass transmissive diffraction grating has a damage threshold several orders of magnitude higher than metal-deposited reflective diffraction grating. Therefore, when a transmission type diffraction grating is used, an effective pulse width conversion device can be configured for one having a large peak output (peak power) of emitted light from an ultrashort pulse laser amplifier.
- the transmission diffraction grating can set an optical path in the space on both sides of the substrate.
- the reflective diffraction grating can use only one space with respect to the substrate. For this reason, when an actual optical system is configured using a reflection type diffraction grating, downsizing of the system is limited due to geometric interference between optical elements and mounts. In order to reduce the size of the pulse width conversion apparatus according to the present embodiment, it is more effective to use a transmission diffraction grating. Furthermore, if the damage threshold value of the transmission diffraction grating made of quartz glass is used, the cross section of the laser beam incident on the pulse width converter can be reduced. Therefore, since a small optical element can be selected, further downsizing of the system can be further promoted.
- the pulse width conversion device and the optical amplification system according to the present invention are not limited to the above-described embodiments and configuration examples, and various modifications are possible.
- the pulse width conversion device is a pulse width conversion device that generates an output light pulse having a pulse width different from the pulse width of the input light pulse, and (1) the input light pulse input along the first optical path. Is output along the second optical path at an emission angle corresponding to the wavelength, and a light beam input at an incident angle corresponding to the wavelength along the third optical path is output at a constant emission angle along the fourth optical path. The light beam input at a constant incident angle along the fifth optical path is output at the output angle according to the wavelength along the sixth optical path, and the light beam input at the incident angle according to the wavelength along the seventh optical path is combined.
- a light beam output from the spectroscopic element along the second optical path at an emission angle according to the wavelength is output to the spectroscopic element as a third optical path.
- a configuration is used that includes a third optical system that inputs a light beam output at an emission angle according to the wavelength along the optical path to the spectroscopic element at an incident angle according to the wavelength along the seventh optical path.
- the incident / exit direction by the combination of the third optical path and the fourth optical path is the input / output direction by the combination of the first optical path and the second optical path with respect to the incident / exit direction of the light flux in the spectroscopic element.
- a different configuration is used.
- the spectroscopic element is preferably a transmission diffraction grating. It is also preferable that the spectroscopic element is a reflective diffraction grating.
- the first optical system and the third optical system are integrated. Further, it is preferable that the spectroscopic element, the first optical system, and the third optical system are integrated. Moreover, it is preferable that the spectroscopic element, the first optical system, the second optical system, and the third optical system are integrated.
- the first optical system and / or the third optical system adjust the optical path length from the light output from the spectroscopic element to the light input to the spectroscopic element. Is preferably included.
- the incident angle when the light beam is input to the spectroscopic element along the fifth optical path is when the light beam is output from the spectroscopic element along the fourth optical path. It is preferable to be equal to the emission angle.
- an optical amplification device that optically amplifies an optical pulse
- an optical pulse that is optically amplified by the optical amplification device is input, and dispersion of the input optical pulse is compensated.
- a pulse width conversion device configured as described above for outputting the optical pulse.
- the present invention can be used as a pulse width conversion device that can be easily reduced in size and an optical amplification system that includes such a pulse width conversion device and that can be easily reduced in size.
- Yb-doped optical fiber 54 ... collimator lens, 55 ... ⁇ / 4 plate, 56 ... ⁇ / 2 plate, 57 ... polarizing beam splitter, 58 ... Faraday rotator, 59 ... ⁇ / 2 plate, 60 ... polarizing beam splitter, 61 ... reflecting mirror, 62 ... ⁇ / 4 plate, 63 ... condensing lens, 64 ... single mode optical fiber, P 1 ... first optical path, P 2 ... second optical path, P 3 Third optical path, P 4 ... fourth optical path, P 5 ... fifth optical path, P 6 ... sixth optical path, P 7 ... seventh optical path, P 8 ... eighth optical path, Pi ... input light pulse, Po ... output optical pulse .
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Abstract
Description
Claims (9)
- 入力光パルスのパルス幅と異なるパルス幅を有する出力光パルスを生成するパルス幅変換装置であって、
第1光路に沿って入力した前記入力光パルスを分光して第2光路に沿って波長に応じた出射角で出力し、第3光路に沿って波長に応じた入射角で入力した光束を第4光路に沿って一定の出射角で出力し、第5光路に沿って一定の入射角で入力した光束を第6光路に沿って波長に応じた出射角で出力し、第7光路に沿って波長に応じた入射角で入力した光束を合波して第8光路に沿って前記出力光パルスとして出力する分光素子と、
前記分光素子から前記第2光路に沿って波長に応じた出射角で出力された光束を、前記分光素子へ前記第3光路に沿って波長に応じた入射角で入力させる第1光学系と、
前記分光素子から前記第4光路に沿って一定の出射角で出力された光束を、前記分光素子へ前記第5光路に沿って一定の入射角で入力させる第2光学系と、
前記分光素子から前記第6光路に沿って波長に応じた出射角で出力された光束を、前記分光素子へ前記第7光路に沿って波長に応じた入射角で入力させる第3光学系と、
を備え、
前記分光素子における光束の入出射方向に関して、前記第3光路および前記第4光路の組み合わせによる入出射方向が、前記第1光路および前記第2光路の組み合わせによる入出射方向と異なる、
ことを特徴とするパルス幅変換装置。 - 前記分光素子が透過型回折格子であることを特徴とする請求項1に記載のパルス幅変換装置。
- 前記分光素子が反射型回折格子であることを特徴とする請求項1に記載のパルス幅変換装置。
- 前記第1光学系および前記第3光学系が一体化されていることを特徴とする請求項1~3の何れか1項に記載のパルス幅変換装置。
- 前記分光素子、前記第1光学系および前記第3光学系が一体化されていることを特徴とする請求項1~3の何れか1項に記載のパルス幅変換装置。
- 前記分光素子、前記第1光学系、前記第2光学系および前記第3光学系が一体化されていることを特徴とする請求項1~3の何れか1項に記載のパルス幅変換装置。
- 前記第1光学系および前記第3光学系の双方または何れか一方が、前記分光素子からの光出力から前記分光素子への光入力までの光路長を調整する光路長調整部を含む、ことを特徴とする請求項1~6の何れか1項に記載のパルス幅変換装置。
- 前記第2光学系において、前記分光素子へ前記第5光路に沿って光束が入力されるときの入射角が、前記分光素子から前記第4光路に沿って光束が出力されるときの出射角と等しい、ことを特徴とする請求項1~7の何れか1項に記載のパルス幅変換装置。
- 光パルスを光増幅する光増幅装置と、
前記光増幅装置により光増幅された光パルスを入力し、その入力した光パルスの分散を補償して該光パルスを出力する請求項1~8の何れか1項に記載のパルス幅変換装置と、
を備えることを特徴とする光増幅システム。
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- 2010-07-08 CN CN201080038096.0A patent/CN102484348B/zh not_active Expired - Fee Related
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Also Published As
Publication number | Publication date |
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CN102484348A (zh) | 2012-05-30 |
KR20120075458A (ko) | 2012-07-06 |
JP5637669B2 (ja) | 2014-12-10 |
EP2475055A4 (en) | 2017-12-13 |
US20120147457A1 (en) | 2012-06-14 |
JP2011054737A (ja) | 2011-03-17 |
KR101718177B1 (ko) | 2017-03-20 |
US8797641B2 (en) | 2014-08-05 |
CN102484348B (zh) | 2014-08-06 |
EP2475055A1 (en) | 2012-07-11 |
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