CA2179268A1 - Single grating laser pulse stretcher and compressor - Google Patents
Single grating laser pulse stretcher and compressorInfo
- Publication number
- CA2179268A1 CA2179268A1 CA002179268A CA2179268A CA2179268A1 CA 2179268 A1 CA2179268 A1 CA 2179268A1 CA 002179268 A CA002179268 A CA 002179268A CA 2179268 A CA2179268 A CA 2179268A CA 2179268 A1 CA2179268 A1 CA 2179268A1
- Authority
- CA
- Canada
- Prior art keywords
- laser beam
- pulsed laser
- reflector
- directed
- grating element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- 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
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
- G02B27/0944—Diffractive optical elements, e.g. gratings, holograms
-
- 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
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0911—Anamorphotic systems
-
- 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
- G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
- G02B27/4233—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive element [DOE] contributing to a non-imaging application
-
- 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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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Lasers (AREA)
Abstract
A single-grating method and apparatus is described for a laser pulse stretcher and compressor (30). The method and apparatus exploit a two-layer vertical structure: one layer for the stretcher section (elements 32, 34, 36, and 38) and one layer for the compressor section (elements 32, 40a, and 40b). This allows additional components to be disposed between the respective stretcher and compressor sections. Applications are described for chirped-pulse and regenerative amplifiers, where tuning is desired. When a change in the input wavelength is applied, only one rotational adjustment is required to resume the alignment of the whole stretcher and compressor.
Description
Wo gS120178 ~17 g 2 6 8 PCT/US94/00704 TITLE OF THE lNVhh.
Single Grating I.aser Pulse Stretcher and Compres60r -~
P~ OF THE lNVhr~
Thi8 invention relates to temporally stretch and compress laser pulses and particularly for the application of amplifying sub-picosecond laser pulses (less than 1 ps) to an energy level greater than 100 micro joules (J) per pulse. An optical pulse stretcher-compressor is a key element in a chirped-pulse or regenerative laser amplifier for amplifying sub-picosecond laser pulses to an energy level greater than 100 micro joule per pulse. In this application, the stretcher is used to lengthen the optical pulses before the amplification, and the compressor is used to resume the original pulse duration after the amplification. In this way, the peak power inside the amplifier cavity can be kept low enough to avoid any damage to the optical elements and avoid nonlinear distortion on the pulse shape and beam profile.
Using a pair of diffraction gratings to compress optical pulses was proposed by Treacy 1 in 1969 and then by Martinez 2 in 19~7. Grating-based optical pulse stretcher and compressor were first investigated experimentally by Pessot, Maine, and Mourou 3 in 1987.
In the early design of Pessot etc. 3, four identical diffraction gratings were used. Two of the gratings were used in the stretcher to lengthen an ultrashort laser pulse by introducing a positive group velocity dispersion to the pulse.
The other two gratings were used in the compressor to compensate precisely the phase modulation in the stretched pulse by introducing a negative group velocity dispersion.
Recent advances in self mode-locked Titanium: sapphire lasers and regenerative Titanium:sapphire amplifiers have led to a rapid development of laser pulse stretcher-compressors.
Modified designs of the Pessot's stretcher-compressor 3 are commercially available and have four gratings 4, three gratings 5,6 or two gratings 7 . Although the basic r-chAn; Rm Wo 9'v20178 PCT/US94/00704 ~1 79268 2 of phese modulation remains the same, these new designs greatly simplify the structure o~ the instrument and reduce the difficulty in alignment.
However, a major problem remains in all of those multiple-grating stretcher-compressors, namely, all the gratings requlre ~recise read~ustment when a change in the laser wavelength is required. These adjustments are extremely inconvenient when frequent changes in laser wavelength is required. Beside6, strictly matched grating pa~rs are required in the stretcher and compressor in order to obtain required good beam profiles and appropriate pulse duration.
There is a continuing need for i ,-- v~ ~ ~s in apparatus and methods for laser pulse stretcher-compressors.
Refe.. ~-1. E. B. Treacy, optical pulse compression with diffraction gratings, IEEE Journal of Quantum Electronics, QE-- 5 (9),454 (1969).
2. 0. E. Martinez,3000 times grating compressor with positive group velocity dispersion: application to fiber compensation in 1. 3- l . 6 micro m region, IEFE Journal of Quantum Electronlcs, QE-23 (1),454 (1987).
Single Grating I.aser Pulse Stretcher and Compres60r -~
P~ OF THE lNVhr~
Thi8 invention relates to temporally stretch and compress laser pulses and particularly for the application of amplifying sub-picosecond laser pulses (less than 1 ps) to an energy level greater than 100 micro joules (J) per pulse. An optical pulse stretcher-compressor is a key element in a chirped-pulse or regenerative laser amplifier for amplifying sub-picosecond laser pulses to an energy level greater than 100 micro joule per pulse. In this application, the stretcher is used to lengthen the optical pulses before the amplification, and the compressor is used to resume the original pulse duration after the amplification. In this way, the peak power inside the amplifier cavity can be kept low enough to avoid any damage to the optical elements and avoid nonlinear distortion on the pulse shape and beam profile.
Using a pair of diffraction gratings to compress optical pulses was proposed by Treacy 1 in 1969 and then by Martinez 2 in 19~7. Grating-based optical pulse stretcher and compressor were first investigated experimentally by Pessot, Maine, and Mourou 3 in 1987.
In the early design of Pessot etc. 3, four identical diffraction gratings were used. Two of the gratings were used in the stretcher to lengthen an ultrashort laser pulse by introducing a positive group velocity dispersion to the pulse.
The other two gratings were used in the compressor to compensate precisely the phase modulation in the stretched pulse by introducing a negative group velocity dispersion.
Recent advances in self mode-locked Titanium: sapphire lasers and regenerative Titanium:sapphire amplifiers have led to a rapid development of laser pulse stretcher-compressors.
Modified designs of the Pessot's stretcher-compressor 3 are commercially available and have four gratings 4, three gratings 5,6 or two gratings 7 . Although the basic r-chAn; Rm Wo 9'v20178 PCT/US94/00704 ~1 79268 2 of phese modulation remains the same, these new designs greatly simplify the structure o~ the instrument and reduce the difficulty in alignment.
However, a major problem remains in all of those multiple-grating stretcher-compressors, namely, all the gratings requlre ~recise read~ustment when a change in the laser wavelength is required. These adjustments are extremely inconvenient when frequent changes in laser wavelength is required. Beside6, strictly matched grating pa~rs are required in the stretcher and compressor in order to obtain required good beam profiles and appropriate pulse duration.
There is a continuing need for i ,-- v~ ~ ~s in apparatus and methods for laser pulse stretcher-compressors.
Refe.. ~-1. E. B. Treacy, optical pulse compression with diffraction gratings, IEEE Journal of Quantum Electronics, QE-- 5 (9),454 (1969).
2. 0. E. Martinez,3000 times grating compressor with positive group velocity dispersion: application to fiber compensation in 1. 3- l . 6 micro m region, IEFE Journal of Quantum Electronlcs, QE-23 (1),454 (1987).
3. M. Pessot, P. Maine and G. Mourou, 1000 times expansion/compression of optical pulses for chirped pulse amplification, Optics f' nir;tions,62 (6), 419 (1987).
4. Quantronlx product catalog, Model 4800 ~sunami Amplifier, Quantronix,49 Wireless Blvd., PØ Box 9014, Smithtown, NY 11787.
5 . Spectra-Physics product catalog, 0 .1 TW
Ti:sapphire Ampli~ier System, Spectra-Physics Lasers, 1330 Terra Bella Ave., PØ Box 7013, Mountain View, CA 94039.
Ti:sapphire Ampli~ier System, Spectra-Physics Lasers, 1330 Terra Bella Ave., PØ Box 7013, Mountain View, CA 94039.
6. Continuum product catalog, Ti: sapphire Terawatt Laser, Continuum, 408727-3240 .
7. Quantronix product catalog, Model 4820 Stretcher/Compressor, Quantronix,49 Wireles8 Blvd., PØ
Box 9014, Smithtown, NY 11787.
Wo 95/20178 PCTIUS94/00704 ~7926g SUMMPRY OF THE lhvl~n..lUb The invention is directed to a new and novel method for combined pulse stretching and compresaion of a pulsed laser beam of various different output frequencies. The device utilizcs a single grating device for both stretching and compressing of a laser pulse. The grating device has vertical height sufficient for six different level beam passes, namely, four passes for the stretcher and two passes for the compres sor .
For the stretcher, the beam enters and strikes the grating and is directed through collimating optics, as for example, focusing lcns, converging mirror or equivalent, to a mirror, the beam from the mirror is directed back to the grating element, the beam returns through the optics again striking a retro-reflective device such as for example, a roof mirror or the equivalent, the beam is again reflected to the grating, reflected from the grating to a mirror through collimating optics, reflected back to the grating, and exits the stretcher and enters a pulse amplifier.
When amplified, the beam enters a compressor in which utilizes the bottom portion of the grating element of the stretcher. The amplified beam enters the compressor and is directed toward the grating element, to a retro-reflective device, back to the grating element, to a mirror ref lector, back to the grating, back to the retro-reflector device, a6 described above, from the retro-reflector to the grating and out for intended use now amplified and in substantially in its original pulse width.
When the frequency of the laser is changed the only element that need adjusting is the diffraction grating.
Preferably the grating element is adjusted only.
An object of this invention is to produce a laser pulse stretcher-compressor that requires only the adjustment of one grating when the pulse frequency is changed.
Another object of this invention is to provide a combined ~17~268 laser pulse stretcher and compressor utilizing a common grating element.
These and other objects and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed specification in which the preferred ~ m~nt is described in conjunction with the accompanying drawing Figures.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
FLgure l depicts a schematic showing of the prior art pulse stretcher;
Figure 2 depicts a schematic showing of a prior art grating pulse compressor;
Figure 3 depicts a schematic showing of a side view showing of the combined pulse stretcher-compressor of the invention showing beam vertical elevations;
Figure 4 depicts a plan view showing of Figure 3 showing the beam path of the stretcher portion of the device; and Figure 5 depicts a plan view showing of the bottom portion of the Figure 3 showing taken along line 5-5 of Figure 3.
nT.~z~TT~n DESCRIPTION OF THE DRAWING FIGURES
Referring now to the various drawing Figures and particularly to prior art drawing figures 1 and 2, In drawing Figure 1 a grating pulse stretcher 10 is depicted. A pulsed laser beam 12 is introduced into the ntretcher and impacts i~put mirror 14 which reflects the beam to grating 16. The beam is directed from the grating to a second mirror 18 through a collimating lens 19, reflected back to the grating through lens l9 and from the grating to a step down prism 23, the beam is reflected from the step down prism back to the grating, reflected from the grating through lens 19 to the second mirror 18, reflected from the second mirror through collimating lens l9, focusing element, to the grating, from the grating the beam is directed to output mirror 20 as a stretched beam which is directed to a pulses amplifier 21 well .
Wo 9Y20178 PCrlUS94/0070~
2~7926g known in this art . Ref erring now to prior art drawing Figure 2, after amplification the amplified-stretched beam 22 is directed into a compressor 80 that the original pulse duration can be re-established. The beam 22 is directed to an input mirror 14a to a mirror 18a to a grating 26, to a second grating 26a, to a step down retro-reflector 18b, reflected back to grating 26a, reflected back to grating 26, reflected to mirror 18a, reflected to mirror 28 and reflected out for the amplified beam's intended use.
In the prior art showings the gratings 26 and 26a have to be repositioned with each beam frequency change. This requires precise parallel alignment of the two gratings 26 and 26a. This requires considerable operator skill for the re-positioning and is very time consuming. Many different frequency changes results in considerable down time repositioning the gratings.
Figures 3-5 depict the stretcher-compressor 30 of the invention showing a single grating vertically stacked stretcher-compressor. Figure 3 is a side view of the apparatus 30. The top portion (layer) is the laser pulse beam stretcher portion and the bottom portion (layer) is the laser pulse compressor portion. Figure 4 is a top plan view of the stretcher, and Figure 5 is a top plan view of the compressor taken along line 5-5 of Figure 3.
~ 8 shown in drawing Figure 4, the stretcher portion consists of the top half of a diffraction grating 32.
Typically a 2"x 4" rectangle with 1800 grooves per millimeter and gold coated, a focusing element such as for example, a lens 34 typically having a focal length of 50 cm, 1" x 3.5"
and an antireflection coating (AR), a flat mirror 36 having a dimension of 2"x 2", a high reflection (HR) coating, and a retro-reflective device herein after referred to as a roof mirror reflector 38 typlcal a rectangular of 0.5~x 3"~ HR
coated f or vertical displacement .
As shown in Figure 5, the compressor portion composes the 8 2 ~ ~ 9 2 6 8 Pcr/uS94/0070~l bottom half of the grating 32, a roof mirror reflector 40a typically a rectangle of l" x 3", HR coated) for horizontal displacement, and a roof mirror ref lector 42 having typical dimensions of 0.5" x 3", HR coated for vertical displacement.
As shown in ~igures. 3 and 4, a beam 44 of laser pul6es to be 6tretched impinge6 on grating 32 in an angle near a Littrow angle. Its fir~t order diffracted beam 46 hit6 len4 34. The tran6mitted beam 48 from the len6 hit6 mirror 36.
The reflected beam 50 from the mirror i6 directed to len6 34.
Then the beam 52 from len6 34 i6 directed to grating 32. ~en6 34 i6 vertically di6placed down, a6 for example, 3/8" from the level of input beam 44. The returning beam 52 i6 lower than beam 44 a6 for example, 3/4" lower. The returning beam 52 i6 re-collimated by grating 32. The re-collimated beam 54 is directed from the grating to roof mirror reflector 38. The reflected beam 56 from the roof mirror reflector i6 spaced above beam 54 by approximately l/4" and is directed to grating 32. Then the diffracted beam 58 from the grating is directed to lens 34. The beam 60 leaving Lens 34 is directed to mirror 36. The reflected beam 62 leaving mirror 36 passe6 through len6 34. The tran6mitted beam 64 leaving len6 34 i6 directed to grating 32. The beam leaving the grating is the stretched beam 66 is the output beam of the 6tretcher. That i6, after impacting the grating 32 for the fourth time, the ultrashort pulses of input beam 44 become linearly chirped, 6tretched pul6e6 of output beam 66. Thi6 output beam 66 propagate6 in the oppo6ite direction of and with a di6placement down input beam 44 as for example, l/4".
In another embodiment the pulse duration can be modified.
The diffracted beam 46 after the grating element 32 is spatially spread out in the horizontal direction. The extent of this spread is defined by the spectral content of the laser pulse. An aperture 47 of a smaller dimen6ion can be in6erted in the beam path after beam po6ition 46. The 6patial content of the la6er beam i6 reduced by 6uch aperture 6ize. The -Wo 95/20178 : PCTNS94/0070~
i~l7g2~3 overall effect of reducing the beam spatial content is to increase the temporal profile of the laser pulse before such pulse i5 to be compressed in the pulse compre6sor of the instant invention.
As shown in drawing Figures 3 and 5, a beam 67 of laser pulses to be compressed impinges on grating 32 at the same angle as the input beam 44 of the stretcher. The first-order diffracted beam 66 from the grating hits a roof mirror reflector 40 The reflected beam 68 from the reflector is side ways shifted as for example, about 1 5" from beam 66 and is directed to grating 32. This returning beam 68 is re-collimated by the grating. The re-collimated beam 70 impact6 the retro-reflector 40b, typically a roof mirror reflector.
The reflected beam 72 from the reflector i8 directed below the beam 70 as for example, by about a 1.5" and is directed toward grating 32. The diffracted beam 74 from the grating 32 is directed to roof mirror reflector 40. The reflected beam 76 from the reflector 38a is sideways shifted from beam 74 as for example, about 1/4", and is directed to grating 32. Then the diffracted beam 78 from the grating is the output of the compressor. Again, after hitting grating 32 for the fourth time, the linearly chirped, stretched pulses in input beam 67 become compressed, ultrashort pulses of output beam 78. This output beam 78 propagates in the opposite direction of and ~,rith a displacement down as for example, a 1/4", from input ~eam ~4.
In the stretcher, the spacing between lens 34 and mirror 36 should be equal to the focal length of the lens 34. The distance from grating 32 to lells 34 controls the amount of positive group velocity dispersion, which determines the ratio of pulse stretching. In the compressor, the path length from grating 34 to reflector 36 controls the amount of negative group velocity dispersion, which determines the ratio of pulse compression. The relevant theory can be found in references 2 and 3 above.
Wo 95/20178 2 t 7 9 2 6 ~ PCr/US94/00704 For the application of a regenerative or chirped-pulse amplifier, the output pulses from the stretcher are fed ~8 seed pulses into the amplifier 21. The output pulses from the amplif ier are then directed back as an input to the compressor. The output from the compressor is then of high energy up to 100 micro Joules, ultrashort le6s than 1 pico-second laser pulses.
The constituent elements making up this invention are well known in the pulsed laser beam art.
While specif ic embodiments of the combined laser pulse stretcher/compressor has been shown and fully explained above for the purpose of illustration it should be understood that many alterations, modifications and substitutions may be made to the instant invention disclosure without departing from the spirit and scope of the invention as defined by the appended claims .
Box 9014, Smithtown, NY 11787.
Wo 95/20178 PCTIUS94/00704 ~7926g SUMMPRY OF THE lhvl~n..lUb The invention is directed to a new and novel method for combined pulse stretching and compresaion of a pulsed laser beam of various different output frequencies. The device utilizcs a single grating device for both stretching and compressing of a laser pulse. The grating device has vertical height sufficient for six different level beam passes, namely, four passes for the stretcher and two passes for the compres sor .
For the stretcher, the beam enters and strikes the grating and is directed through collimating optics, as for example, focusing lcns, converging mirror or equivalent, to a mirror, the beam from the mirror is directed back to the grating element, the beam returns through the optics again striking a retro-reflective device such as for example, a roof mirror or the equivalent, the beam is again reflected to the grating, reflected from the grating to a mirror through collimating optics, reflected back to the grating, and exits the stretcher and enters a pulse amplifier.
When amplified, the beam enters a compressor in which utilizes the bottom portion of the grating element of the stretcher. The amplified beam enters the compressor and is directed toward the grating element, to a retro-reflective device, back to the grating element, to a mirror ref lector, back to the grating, back to the retro-reflector device, a6 described above, from the retro-reflector to the grating and out for intended use now amplified and in substantially in its original pulse width.
When the frequency of the laser is changed the only element that need adjusting is the diffraction grating.
Preferably the grating element is adjusted only.
An object of this invention is to produce a laser pulse stretcher-compressor that requires only the adjustment of one grating when the pulse frequency is changed.
Another object of this invention is to provide a combined ~17~268 laser pulse stretcher and compressor utilizing a common grating element.
These and other objects and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed specification in which the preferred ~ m~nt is described in conjunction with the accompanying drawing Figures.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
FLgure l depicts a schematic showing of the prior art pulse stretcher;
Figure 2 depicts a schematic showing of a prior art grating pulse compressor;
Figure 3 depicts a schematic showing of a side view showing of the combined pulse stretcher-compressor of the invention showing beam vertical elevations;
Figure 4 depicts a plan view showing of Figure 3 showing the beam path of the stretcher portion of the device; and Figure 5 depicts a plan view showing of the bottom portion of the Figure 3 showing taken along line 5-5 of Figure 3.
nT.~z~TT~n DESCRIPTION OF THE DRAWING FIGURES
Referring now to the various drawing Figures and particularly to prior art drawing figures 1 and 2, In drawing Figure 1 a grating pulse stretcher 10 is depicted. A pulsed laser beam 12 is introduced into the ntretcher and impacts i~put mirror 14 which reflects the beam to grating 16. The beam is directed from the grating to a second mirror 18 through a collimating lens 19, reflected back to the grating through lens l9 and from the grating to a step down prism 23, the beam is reflected from the step down prism back to the grating, reflected from the grating through lens 19 to the second mirror 18, reflected from the second mirror through collimating lens l9, focusing element, to the grating, from the grating the beam is directed to output mirror 20 as a stretched beam which is directed to a pulses amplifier 21 well .
Wo 9Y20178 PCrlUS94/0070~
2~7926g known in this art . Ref erring now to prior art drawing Figure 2, after amplification the amplified-stretched beam 22 is directed into a compressor 80 that the original pulse duration can be re-established. The beam 22 is directed to an input mirror 14a to a mirror 18a to a grating 26, to a second grating 26a, to a step down retro-reflector 18b, reflected back to grating 26a, reflected back to grating 26, reflected to mirror 18a, reflected to mirror 28 and reflected out for the amplified beam's intended use.
In the prior art showings the gratings 26 and 26a have to be repositioned with each beam frequency change. This requires precise parallel alignment of the two gratings 26 and 26a. This requires considerable operator skill for the re-positioning and is very time consuming. Many different frequency changes results in considerable down time repositioning the gratings.
Figures 3-5 depict the stretcher-compressor 30 of the invention showing a single grating vertically stacked stretcher-compressor. Figure 3 is a side view of the apparatus 30. The top portion (layer) is the laser pulse beam stretcher portion and the bottom portion (layer) is the laser pulse compressor portion. Figure 4 is a top plan view of the stretcher, and Figure 5 is a top plan view of the compressor taken along line 5-5 of Figure 3.
~ 8 shown in drawing Figure 4, the stretcher portion consists of the top half of a diffraction grating 32.
Typically a 2"x 4" rectangle with 1800 grooves per millimeter and gold coated, a focusing element such as for example, a lens 34 typically having a focal length of 50 cm, 1" x 3.5"
and an antireflection coating (AR), a flat mirror 36 having a dimension of 2"x 2", a high reflection (HR) coating, and a retro-reflective device herein after referred to as a roof mirror reflector 38 typlcal a rectangular of 0.5~x 3"~ HR
coated f or vertical displacement .
As shown in Figure 5, the compressor portion composes the 8 2 ~ ~ 9 2 6 8 Pcr/uS94/0070~l bottom half of the grating 32, a roof mirror reflector 40a typically a rectangle of l" x 3", HR coated) for horizontal displacement, and a roof mirror ref lector 42 having typical dimensions of 0.5" x 3", HR coated for vertical displacement.
As shown in ~igures. 3 and 4, a beam 44 of laser pul6es to be 6tretched impinge6 on grating 32 in an angle near a Littrow angle. Its fir~t order diffracted beam 46 hit6 len4 34. The tran6mitted beam 48 from the len6 hit6 mirror 36.
The reflected beam 50 from the mirror i6 directed to len6 34.
Then the beam 52 from len6 34 i6 directed to grating 32. ~en6 34 i6 vertically di6placed down, a6 for example, 3/8" from the level of input beam 44. The returning beam 52 i6 lower than beam 44 a6 for example, 3/4" lower. The returning beam 52 i6 re-collimated by grating 32. The re-collimated beam 54 is directed from the grating to roof mirror reflector 38. The reflected beam 56 from the roof mirror reflector i6 spaced above beam 54 by approximately l/4" and is directed to grating 32. Then the diffracted beam 58 from the grating is directed to lens 34. The beam 60 leaving Lens 34 is directed to mirror 36. The reflected beam 62 leaving mirror 36 passe6 through len6 34. The tran6mitted beam 64 leaving len6 34 i6 directed to grating 32. The beam leaving the grating is the stretched beam 66 is the output beam of the 6tretcher. That i6, after impacting the grating 32 for the fourth time, the ultrashort pulses of input beam 44 become linearly chirped, 6tretched pul6e6 of output beam 66. Thi6 output beam 66 propagate6 in the oppo6ite direction of and with a di6placement down input beam 44 as for example, l/4".
In another embodiment the pulse duration can be modified.
The diffracted beam 46 after the grating element 32 is spatially spread out in the horizontal direction. The extent of this spread is defined by the spectral content of the laser pulse. An aperture 47 of a smaller dimen6ion can be in6erted in the beam path after beam po6ition 46. The 6patial content of the la6er beam i6 reduced by 6uch aperture 6ize. The -Wo 95/20178 : PCTNS94/0070~
i~l7g2~3 overall effect of reducing the beam spatial content is to increase the temporal profile of the laser pulse before such pulse i5 to be compressed in the pulse compre6sor of the instant invention.
As shown in drawing Figures 3 and 5, a beam 67 of laser pulses to be compressed impinges on grating 32 at the same angle as the input beam 44 of the stretcher. The first-order diffracted beam 66 from the grating hits a roof mirror reflector 40 The reflected beam 68 from the reflector is side ways shifted as for example, about 1 5" from beam 66 and is directed to grating 32. This returning beam 68 is re-collimated by the grating. The re-collimated beam 70 impact6 the retro-reflector 40b, typically a roof mirror reflector.
The reflected beam 72 from the reflector i8 directed below the beam 70 as for example, by about a 1.5" and is directed toward grating 32. The diffracted beam 74 from the grating 32 is directed to roof mirror reflector 40. The reflected beam 76 from the reflector 38a is sideways shifted from beam 74 as for example, about 1/4", and is directed to grating 32. Then the diffracted beam 78 from the grating is the output of the compressor. Again, after hitting grating 32 for the fourth time, the linearly chirped, stretched pulses in input beam 67 become compressed, ultrashort pulses of output beam 78. This output beam 78 propagates in the opposite direction of and ~,rith a displacement down as for example, a 1/4", from input ~eam ~4.
In the stretcher, the spacing between lens 34 and mirror 36 should be equal to the focal length of the lens 34. The distance from grating 32 to lells 34 controls the amount of positive group velocity dispersion, which determines the ratio of pulse stretching. In the compressor, the path length from grating 34 to reflector 36 controls the amount of negative group velocity dispersion, which determines the ratio of pulse compression. The relevant theory can be found in references 2 and 3 above.
Wo 95/20178 2 t 7 9 2 6 ~ PCr/US94/00704 For the application of a regenerative or chirped-pulse amplifier, the output pulses from the stretcher are fed ~8 seed pulses into the amplifier 21. The output pulses from the amplif ier are then directed back as an input to the compressor. The output from the compressor is then of high energy up to 100 micro Joules, ultrashort le6s than 1 pico-second laser pulses.
The constituent elements making up this invention are well known in the pulsed laser beam art.
While specif ic embodiments of the combined laser pulse stretcher/compressor has been shown and fully explained above for the purpose of illustration it should be understood that many alterations, modifications and substitutions may be made to the instant invention disclosure without departing from the spirit and scope of the invention as defined by the appended claims .
Claims (15)
1. A stretcher for a pulsed laser beam, said pulsed laser beam having a predetermined frequency comprising;
a single laser beam defracting grating element, said grating element having a vertical and horizontal dimension:
a focusing element;
a reflector; and a retro-reflective element;
means for directing said pulsed laser beam;
wherein said pulse laser beam is directed firstly to said grating element, secondly from said grating element back through said focusing element to said reflector, thirdly reflected back from said reflector through said focusing element to said grating element, fourthly defracted from said grating element and to said retro-reflective element where said beam is reflected along a substantially parallel path and fifthly said pulsed laser beam is re-directed to said grating element, and sixthly diffracted from said grating element through said focusing element onto said reflector and seventhly from said reflector through said focusing element to said grating element and eighthly from said grating element out of said pulsed laser beam stretcher for further processing, said firstly directed pulsed laser beam is vertically offset from said eighthly directed pulsed laser beam.
a single laser beam defracting grating element, said grating element having a vertical and horizontal dimension:
a focusing element;
a reflector; and a retro-reflective element;
means for directing said pulsed laser beam;
wherein said pulse laser beam is directed firstly to said grating element, secondly from said grating element back through said focusing element to said reflector, thirdly reflected back from said reflector through said focusing element to said grating element, fourthly defracted from said grating element and to said retro-reflective element where said beam is reflected along a substantially parallel path and fifthly said pulsed laser beam is re-directed to said grating element, and sixthly diffracted from said grating element through said focusing element onto said reflector and seventhly from said reflector through said focusing element to said grating element and eighthly from said grating element out of said pulsed laser beam stretcher for further processing, said firstly directed pulsed laser beam is vertically offset from said eighthly directed pulsed laser beam.
2. A compressor for a pulsed laser beam compressor having a predetermined frequency comprising:
a first retro-reflector;
a grating element;
a second retro-reflector; and a means for directing said laser beam;
wherein said pulsed laser beam is firstly directed to said grating element and secondly diffracted from said grating element to said first retro-reflector, thirdly reflected from said first retro-reflector to said grating element, fourthly the pulsed laser beam is directed to said second retro-reflector where the beam elevation is changed, fifthly said pulsed laser beam is directed back to said grating means, sixthly directed to said first reto-reflector, seventhly reflected back to said grating element and eighthly out of said compressor, said secondly directed pulsed laser beam is horizontally off set from said thirdly directed pulsed laser beam and said secondly directed pulsed laser beam and said firstly directed, pulsed laser beam is off set vertically from said eighthly directed pulsed laser beam.
a first retro-reflector;
a grating element;
a second retro-reflector; and a means for directing said laser beam;
wherein said pulsed laser beam is firstly directed to said grating element and secondly diffracted from said grating element to said first retro-reflector, thirdly reflected from said first retro-reflector to said grating element, fourthly the pulsed laser beam is directed to said second retro-reflector where the beam elevation is changed, fifthly said pulsed laser beam is directed back to said grating means, sixthly directed to said first reto-reflector, seventhly reflected back to said grating element and eighthly out of said compressor, said secondly directed pulsed laser beam is horizontally off set from said thirdly directed pulsed laser beam and said secondly directed pulsed laser beam and said firstly directed, pulsed laser beam is off set vertically from said eighthly directed pulsed laser beam.
3. A combined pulsed laser beam stretcher and compressor, said pulsed laser beam having a predetermined frequency comprising:
a single laser beam diffracting grating element, said single grating element having a vertical and horizontal dimension;
a focusing element;
a first reflector;
a first retro-reflector;
a second retro-reflector;
a third retro-reflector;
a pulsed laser amplifying means for amplifying said pulsed laser beam, said pulsed laser amplifying means having an input and an output; and means for directing said laser beam;
wherein said pulsed laser beam is directed firstly to said grating element, secondly from said grating element through said focusing element to said first reflector, thirdly reflected back from said first reflector through said focusing element to said grating element, fourthly diffracted from said grating element and directed to said first retro-reflector where said beam is reflected along a parallel path and fifthly said pulsed laser beam is re-directed back to said grating element, and sixthly diffracted from said grating element through said focusing element onto said first reflector and seventhly from said first reflector through said focusing element to said grating element and eighthly from said grating element out of said pulsed laser beam stretcher for further processing, and said firstly directed pulsed laser beam is vertically offset from said eighthly directed pulsed laser beam and the output beam from said stretcher is directed to the input of said pulsed laser amplifying means, the amplified output from said pulsed laser amplifying means is firstly directed to said grating element and secondly diffracted from said grating element to said second retro-reflector, thirdly directly from said second retro-reflector to said grating element, fourthly said pulsed laser beam is directed to said third retro-reflector where its beam elevation is changed, fifthly said pulsed laser beam isdirected back to said grating means, sixthly directed to said second retro-reflector, seventhly reflected back to said grating element and eighthly directed out of said compressor, said secondly directed pulsed laser beam from said amplifier is horizontally off set from said thirdly directed pulsed laser beam from said laser amplifier and said firstly directed pulsed laser beam from said amplifier is off set vertically from said eighthly directed pulsed laser beam exiting from the output of said compressor.
a single laser beam diffracting grating element, said single grating element having a vertical and horizontal dimension;
a focusing element;
a first reflector;
a first retro-reflector;
a second retro-reflector;
a third retro-reflector;
a pulsed laser amplifying means for amplifying said pulsed laser beam, said pulsed laser amplifying means having an input and an output; and means for directing said laser beam;
wherein said pulsed laser beam is directed firstly to said grating element, secondly from said grating element through said focusing element to said first reflector, thirdly reflected back from said first reflector through said focusing element to said grating element, fourthly diffracted from said grating element and directed to said first retro-reflector where said beam is reflected along a parallel path and fifthly said pulsed laser beam is re-directed back to said grating element, and sixthly diffracted from said grating element through said focusing element onto said first reflector and seventhly from said first reflector through said focusing element to said grating element and eighthly from said grating element out of said pulsed laser beam stretcher for further processing, and said firstly directed pulsed laser beam is vertically offset from said eighthly directed pulsed laser beam and the output beam from said stretcher is directed to the input of said pulsed laser amplifying means, the amplified output from said pulsed laser amplifying means is firstly directed to said grating element and secondly diffracted from said grating element to said second retro-reflector, thirdly directly from said second retro-reflector to said grating element, fourthly said pulsed laser beam is directed to said third retro-reflector where its beam elevation is changed, fifthly said pulsed laser beam isdirected back to said grating means, sixthly directed to said second retro-reflector, seventhly reflected back to said grating element and eighthly directed out of said compressor, said secondly directed pulsed laser beam from said amplifier is horizontally off set from said thirdly directed pulsed laser beam from said laser amplifier and said firstly directed pulsed laser beam from said amplifier is off set vertically from said eighthly directed pulsed laser beam exiting from the output of said compressor.
4. The invention as defined in claim 1 wherein the predetermined frequency of said pulsed laser beam can be changed to a second predetermined frequency and said stretcher can be adapted tosaid second predetermined frequency by repositioning only said grating element.
5. The invention as defined in claim 2 wherein the predetermined frequency of said pulsed laser beam can be changed to a second predetermined frequency and said compressor can be adapted to said second predetermined frequency by repositioning only said grating element.
6. The invention as defined in claim 3 wherein the predetermined frequency of said pulsed laser beam can be changed to a second predetermined frequency and said stretcher and compressor can be adapted to said second predetermined frequency by repositioning only said grating element.
7. The invention as defined in claim 1 wherein said focusing element is focusinglens.
8. The invention as defined in claim 3 wherein said focusing element is a focusing lens.
9. The invention as defined in claim 1 wherein said retro-reflective element is a roof mirror.
10. The invention as defined in claim 2 wherein said second retro-reflective element is a roof mirror.
11. The invention as defined in claim 3 wherein at least said first and second retro-reflectors are roof mirrors.
12. A combined laser pulse stretcher and compressor device comprising:
a laser source for generating a pulsed laser beam with predetermined spectral content and predetermined temporal pulse width;
a single optical diffracting grating element;
a laser pulse stretcher means for temporally stretching the pulses of said pulsed laser beam; and a temporal compressor means comprising optical elements arranged such that said single diffraction grating is used for both the pulse stretcher means and the laser compressor means to control the temporal stretching and compressing of said laser pulse s wherein the predetermined spectral frequency of said pulsed laser beam can be changed to a second predetermined spectral frequency and said stretcher meansand compressor means can be adapted to said second predetermined frequency by repositioning said single optical diffraction grating element.
a laser source for generating a pulsed laser beam with predetermined spectral content and predetermined temporal pulse width;
a single optical diffracting grating element;
a laser pulse stretcher means for temporally stretching the pulses of said pulsed laser beam; and a temporal compressor means comprising optical elements arranged such that said single diffraction grating is used for both the pulse stretcher means and the laser compressor means to control the temporal stretching and compressing of said laser pulse s wherein the predetermined spectral frequency of said pulsed laser beam can be changed to a second predetermined spectral frequency and said stretcher meansand compressor means can be adapted to said second predetermined frequency by repositioning said single optical diffraction grating element.
13. The invention as defined in claim 12 wherein said pulse stretcher means comprises:
means for directing said pulsed laser beam;
a grating element, said grating element having a vertical and horizontal dimension;
a focusing element;
a mirror reflector;
a roof mirror retro-reflective element;
wherein said pulse laser beam is directed firstly to said grating element, secondly diffracted from said grating element through said focusing element to said reflector, thirdly reflected back from said reflector through said focusing element to said grating element, fourthly diffracted from said grating element to said retro-reflective element where said beam direction is reversed, and fifthly said pulsed laser beam is re-directed to said grating element, and sixthly diffracted from said grating element through said focusing element onto said reflector, seventhly reflected from said reflector through said focusing element back to said grating element, and eighthly diffracted from said grating element out of said laser pulse stretcher for further processing.
means for directing said pulsed laser beam;
a grating element, said grating element having a vertical and horizontal dimension;
a focusing element;
a mirror reflector;
a roof mirror retro-reflective element;
wherein said pulse laser beam is directed firstly to said grating element, secondly diffracted from said grating element through said focusing element to said reflector, thirdly reflected back from said reflector through said focusing element to said grating element, fourthly diffracted from said grating element to said retro-reflective element where said beam direction is reversed, and fifthly said pulsed laser beam is re-directed to said grating element, and sixthly diffracted from said grating element through said focusing element onto said reflector, seventhly reflected from said reflector through said focusing element back to said grating element, and eighthly diffracted from said grating element out of said laser pulse stretcher for further processing.
14. The invention as defined in claim 12 wherein said laser pulse compressor means comprises.
means for directing said laser source;
a grating element, said grating element having a vertical and horizontal dimension;
a first roof mirror retro-reflector;
a second roof mirror retro-reflector;
wherein said pulsed laser beam is firstly directed to said grating element and secondly diffracted from said grating element to said first retro-reflector, thirdly reflected from said first retro-reflector to said grating element, fourthly the pulsed laser beam is diffracted to said second retro-reflector where the beam elevation is changed, fifthly said pulsed laser beam is directed back to said grating means, sixthly directed to said first retro-reflector, seventhly reflected back to said grating element and eighthly diffracted out of said compressor, said secondly directed pulsed laser beam is horizontally offset from said thirdly directed pulsed laser beam, and said fifthly directed pulsed laser beam is offset vertically from said fourthly directed pulsed laser beam.
means for directing said laser source;
a grating element, said grating element having a vertical and horizontal dimension;
a first roof mirror retro-reflector;
a second roof mirror retro-reflector;
wherein said pulsed laser beam is firstly directed to said grating element and secondly diffracted from said grating element to said first retro-reflector, thirdly reflected from said first retro-reflector to said grating element, fourthly the pulsed laser beam is diffracted to said second retro-reflector where the beam elevation is changed, fifthly said pulsed laser beam is directed back to said grating means, sixthly directed to said first retro-reflector, seventhly reflected back to said grating element and eighthly diffracted out of said compressor, said secondly directed pulsed laser beam is horizontally offset from said thirdly directed pulsed laser beam, and said fifthly directed pulsed laser beam is offset vertically from said fourthly directed pulsed laser beam.
15. The invention as defined in claim 12 wherein said grating comprises at leasttwo sections.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/972,169 US5329398A (en) | 1992-11-05 | 1992-11-05 | Single grating laser pulse stretcher and compressor |
| CA002179268A CA2179268A1 (en) | 1992-11-05 | 1994-01-19 | Single grating laser pulse stretcher and compressor |
| JP7519523A JPH09508217A (en) | 1994-01-19 | 1994-01-19 | Single Grating Laser Pulse Stretcher and Compressor |
| PCT/US1994/000704 WO1995020178A1 (en) | 1992-11-05 | 1994-01-19 | Single grating laser pulse stretcher and compressor |
| EP94909474A EP0742912A1 (en) | 1994-01-19 | 1994-01-19 | Single grating laser pulse stretcher and compressor |
| AU62310/94A AU6231094A (en) | 1992-11-05 | 1994-01-19 | Single grating laser pulse stretcher and compressor |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/972,169 US5329398A (en) | 1992-11-05 | 1992-11-05 | Single grating laser pulse stretcher and compressor |
| CA002179268A CA2179268A1 (en) | 1992-11-05 | 1994-01-19 | Single grating laser pulse stretcher and compressor |
| PCT/US1994/000704 WO1995020178A1 (en) | 1992-11-05 | 1994-01-19 | Single grating laser pulse stretcher and compressor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2179268A1 true CA2179268A1 (en) | 1995-07-27 |
Family
ID=27170158
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002179268A Abandoned CA2179268A1 (en) | 1992-11-05 | 1994-01-19 | Single grating laser pulse stretcher and compressor |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2179268A1 (en) |
| WO (1) | WO1995020178A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5847863A (en) * | 1996-04-25 | 1998-12-08 | Imra America, Inc. | Hybrid short-pulse amplifiers with phase-mismatch compensated pulse stretchers and compressors |
| DE10250014B4 (en) * | 2002-10-25 | 2007-08-02 | Universität Kassel | High-performance pulse shaper in compact design |
| FR2872592B1 (en) * | 2004-07-02 | 2006-09-15 | Thales Sa | AMPLIFIER CHAIN FOR THE GENERATION OF ULTRACOURTE LIGHT PULSES OF DIFFERENT PULSE STRESSES |
| EP1851837B1 (en) | 2004-12-20 | 2015-03-04 | Imra America, Inc. | Pulsed laser source with adjustable grating compressor |
| CN100526964C (en) * | 2006-07-28 | 2009-08-12 | 中国科学院上海光学精密机械研究所 | Parallel adjustment method for multiple pairs of gratings |
| CN113206424B (en) * | 2021-04-06 | 2022-04-26 | 北京大学 | Adjusting device and adjusting method for reducing compressor space chirp |
| CN113984222B (en) * | 2021-10-28 | 2024-06-14 | 中山光子科学中心 | Online measuring device and measuring method for wavefront distortion of grating compressor |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4655547A (en) * | 1985-04-09 | 1987-04-07 | Bell Communications Research, Inc. | Shaping optical pulses by amplitude and phase masking |
| US4750809A (en) * | 1985-05-01 | 1988-06-14 | Spectra-Physics, Inc. | Pulse compression |
| US4746193A (en) * | 1986-11-26 | 1988-05-24 | Bell Communications Research, Inc. | Apparatus for stabilization of high speed optical pulses |
| US4834474A (en) * | 1987-05-01 | 1989-05-30 | The University Of Rochester | Optical systems using volume holographic elements to provide arbitrary space-time characteristics, including frequency-and/or spatially-dependent delay lines, chirped pulse compressors, pulse hirpers, pulse shapers, and laser resonators |
| US4928316A (en) * | 1988-02-04 | 1990-05-22 | Bell Communications Research, Inc. | Optical systems and methods based upon temporal stretching, modulation and recompression of ultrashort pulses |
| DE3932097A1 (en) * | 1989-09-26 | 1991-04-04 | Max Planck Gesellschaft | OPTICAL PULSE COMPRESSOR |
| US5166818A (en) * | 1991-03-11 | 1992-11-24 | Bell Communications Research, Inc. | Optical pulse-shaping device and method, and optical communications station and method |
-
1994
- 1994-01-19 CA CA002179268A patent/CA2179268A1/en not_active Abandoned
- 1994-01-19 WO PCT/US1994/000704 patent/WO1995020178A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995020178A1 (en) | 1995-07-27 |
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