Proposal to PAL from SPringS. ring-8 ~ Pulse-stacker

Transcription

1 roposal to AL from ring ring-8 ~ ulse-stacker stacker-based square pulse (>10 10ps) shaping system ~ Hiromistu Tomizawa Accelerator Division, Japan ynchrotron Radiation Research Institute (ring-8) 0. Intro. ~ Recent progress in UV-pulse (>10 ps) shaping ~ 1. Macro-pulse (15~20 ps) generation with UV-pulse stacker 2. assive micro-pulse preparation - rism-pair UV-stretcher + ulse tacker 4. ummary for generation of 15~20-ps UV- quare laser pulse 0. ~10-ps pulse-shaping development in UV (~263 nm): In the year 2006, UV-shaping technologies are matured! 1. AL developed rism-pair UV-pulse stretcher (up to 6 ps with nice shape) Korea 2. UV-pulse stacker was developed by 8 and commercialized for industry. Japan 3. UV-Dazzler (AO) was completed (up to 5 ps) by Fastlite (L Ecole polytechnique) and commercialized. France

2 1. Macro-pulse pulse (15~20 ps) generator (ulse stacking to reach longer square pulse) 1-1. UV-ulse tacker 2~3 ps λ/2 waveplate 4~5 ps 16~20 ps Entrance window should be double AR-coated! Not utilize Brewster Window! The polarization of the input UV-laser is rotated 45 degrees by the half lambda waveplate. UV-laser is split into two equal portions by the each cubic polarizer. But, consider QE deference between and!! 16~24 ps 1. Macro Macro-pulse (15~20 ps) generator 1-2. Chirped pulse with deferent compressor length (in the case of ring-8) Changing compressor length, 2.5-ps original pulse is generated! Not that, laser pulse will be positively chirped & stretched through the silica material! To avoid interferences on the plateau of stacked macro pulse, - and - polarized pulses are alternatively positioned! ositive 20 ps Negative

3 1. Macro-pulse (15~20 ps) generator 1-3. Time chart of pulse stacking 3 stages for generation of 20 ps square pulse ps time 1/2 waveplate 10 ps 1st tage: /2 waveplate 5 ps 2nd tage: 5 ps /2 waveplate 2.5 ps 3rd tage: 2.5 ps 2.5 ps 2.5 ps 1. Macro-pulse (15~20 ps) generator 1-4. Developed & commercialized UV-ulse tacker ~ Combining with DM, the system generates ideal 3D laser pulse ~

4 1. Macro Macro-pulse (15~20 ps) generator D- Laser Beam haping system UV- Laser source (total stability!) Laser ulse Energy : ointing tability & Reproducible Timing Jitter < 1 ps Temporal rofile: ulse duration: 2.5 ~ 20 ps UV- ulse tacker ulse duration: 2.5 ps ulse duration: 10 ps Diameter:1 mm ~ present status at ring-8 ~ patial rofile: Distribution: Flattop Deformable Mirror Gaussian Deformable Mirror ulse tacker 10 pps Deformable Mirror Flattop treak Image of stacked pulses ulse tacker (3 stages) 2. assive micro-pulse preparation - rism-pair UV-stretcher + ulse tacker 2-1. THG-tretching system ~ Combining with ulse stacker, it generates ideal square laser temporal pulse ~ THG & UV-tretcher (prism pair) THG & tretcher nm nm X 10% efficiency = nm nm nm X 50% Loss =125 μj Courtesy of C. Kim =>1 nc from Cathode with Q.E. 10 5

5 2. assive micro-pulse preparation - rism-pair UV-stretcher + ulse tacker 2-2. rism-air Dispersion Courtesy of C. Kim 2. assive micro-pulse preparation - rism-pair UV-stretcher + ulse tacker 2-3. UV-tretcher (rism-air) 400 nm 266 nm 800 nm tretched 266 nm X-tal THG Residual 800 nm Courtesy of C. Kim

6 2. assive micro-pulse preparation - rism-pair UV-stretcher + ulse tacker 2-4. UV-pulse measurement (Cross Correlator) Input pulse 800nm, <100fs 1kHz THG (3w) Residual 800nm low scan 266nm <10ps UV pulse stretcher 800nm, <150fs Optical delay X-tal DFG intensity Detector 400nm DFG Cross correlation = tretched 266nm δt 800nm Optical delay Optical delay δt measurement -> UV 266nm pulsewidth calculation Courtesy of C. Kim 2. assive micro-pulse preparation - rism-pair UV-stretcher + ulse tacker 2-5. UV-pulse duration (with Cross Correlator) Up to 6 ps, it possible to shape nicely. Input UV-laser hould be perfectly collimated to prism-pair. Courtesy of C. Kim

7 3-1. Candidates of LM for UV-Laser pulse shaping DAZZLER (Acousto-optics) optics) imultaneously and independently performing both spectral hase & Amplitude of ultrafast laser pulses. (FATLITE) Fused-silica based LM Utilizing silica plates Directly shaping for UV-Laser Higher Laser power threshold ossible to shape ~ms pulse train ~ However long-term drifting (At present status, very sensitive to temperature fluctuation) ~ ~ Computer-controllable silica plates complex ~ imulated Annealing Algorisms (A) Bimorph iezo actuator ilica plate holder Reflector Laser light ilica plate Axis Compared with other type LM Maker name Cyber Laser Inc. CRI Meadlark Jenoptik Hamamatsu FATLITE roduct name 8 test LM LM λ LM640/12 X8267 T-UV wavelength 200 nm~ limited by gratings & optics 400 nm~ 400 nm~ 400 nm~ 350 nm~ 200~300nm transparency 99% 94% 90% 95% 90% (Reflective) 50% Total efficiency (0.1 nm/pixel) 20% in IR depends on input bandwidth (20 nm) ~ 40% in IR depends on input bandwidth (20 nm) ~ 70% in IR input bandwidth (< 26nm) ~ 70% in IR input bandwidth (< 64 nm) ~ 70% in IR input bandwidth (< 100 nm) 30-50% in UV depends on shaping Damage threshold for amplified pulses (10 Hz) 1TW/cm 2 (100mJ/pulse) 500MW/cm 2 (50μJ/ pulse) 500MW/cm 2 (50μJ/ pulse) 2 GW/cm 2 (100μJ/ pulse) 2GW/cm 2 (200μJ/ pulse) 1GW/cm 2 (100μJ/ pulse) Operating speed 50ms 100 ms 100 ms 100 ms 500 ms 0.04ms ixel number None (No dead space) others Whole system is packaged Only LM Only LM Only LM Only LM Whole system is packaged Fused silica type: Mechanical control Liquid crystal type Electrical addressed type AODF type

8 rinciple of Acousto Optic (AO) ~ DAZZLER ~ TeO 2 crystal Input optical beam Acoustic wave Reflection on the input face 14 Reflection on the output face transducer Adaptation circuitry 3.6 Direct beam 1 Diffracted beam MA plug ( ) cos 2 f V θ θ α = =Δn. a. o ν c cos( θ θ ) o a D.Kaplan and.tournois J.hys.IV France 12 (2002) r5-69 rinciple of AO rogrammable Dispersive Filter: DAZZLER E out ( t) ( t / α) E in ( t) où Example of 4ps square pulse made with UV DAZZLER α = f f ac opt 10 7 E Courtesy of Fastlite out ( ω) ( αω) E in ( ω) Transmitted pulse equals convolution of input pulse and acoustic wave: -single crystal design (few cm 3 ) -quantitative shaping in phase and amplitude -up to few ps shaping ability. -several wavelength available (from IR to UV) But Damage threshold problem In the UV!

9 3-2. Difficulty of UV-Laser pulse measurements treak camera (Hamamatsu fesca-200) In IR temporal resolution of 200 fs, but.. Temporal resolution of 700 fs in UV ossible to measure up to 800 ps FROG or IDER ossible to measure just in IR (normally, <5 ps) pecially ordered FROG for 20 ps UV-Dazzler as FROG or IDER FROG: 0.05 nm 500 fs -20ps HAZZLER (normally, <5 ps) can be one solution for micro-pulse measurement! FROG: 0.3nm 200 fs -2ps 3-3. Combination with DAZZLER shaping in IR, and UV pulse measurement with feedback loop. Oscillator Dazzler tretcher Amplifier Compressor THG ulse stacker UV HAZZLER Courtesy of Fastlite

10 3-4. Features of HAZZLER MEAUREMENT Design based on a single beam geometry Exceptional stability, reproducible results,, user independent Extreme ease of use ( no calibration, very straightforward alignment procedure) FROG, IDER, AUTOCORRELATION within the same instrument by simply flipping a computer switch ingle shot,, non iterative spectral phase and amplitude characterization with the IDER method FROG ( Intensimetric and Interferometric available) traces for complex pulse shapes (multiple pulses, large Time Bandwidth products) Interferometric AutoCorrelation and Intensimetric Autocorrelation available Tunable wavelength range Conventional AUTOCORRELATOR & HG-FROG Replace Detector to pectrometer for FROG AUTOCORRELATOR gcuo/images/others/ HG-FROG AC_fig01.gif ; FROG_fig05.gif

11 BAEBAND INTERFEROMETRIC AUTOCORRELATION ULE MEAUREMENT with DAZZLER ~ HAZZLER ~ pectrometer for FROG Diffracted ignals 1.4 Laser pulse AODF Diffracted beam 1st replica t0 τ 2nd replica τ variable delay Two-photon detector Two-hoton ignal (V) π 0.5 π 0.75 π π 1.25 π 1.5 π 1.75 π Time (fsec) Courtesy of Fastlite IDER as a perfect pulse characterization ~ Conventional IDER CONFIGRATION ~ Courtesy of N.H. Matlis Department of hysics University of Texas *Based on work by C. Iaconis & I.A. Walmsley (Opt.Let. /Vol. 23 No.10/May )

12 IDER for characterization of macro-pulse (stacked pulse train) & micro-pulse (8 ~ Measuring the spectral phase: Conventional IDER~ Modified presentation of Walmsley group, Oxford 790 nm (8-future plan) pectral Interferogram 263 nm 395 nm Feed backing with IDER, ulse stacking can be optimized! Interference term TIME DOMAIN IDER MEAUREMENT with DAZZLER ~ HAZZLER ~ Diffracted ignals st replica 2nd replica 10 Laser pulse Diffracted beam τ pectrometer 3 8 AODF t0 τ variable delay Intensity (AU) hase (Rad) Quasi-monochromatic pulse ς1 generated at t0 ς2= ς1+δς generated at t0+δt Frequency (THz) A.Monmayrant et al. Optics Letters, 28, 4, p (Feb. 15, 2003)

13 4. ummary for generation of 15~20-ps UV- quare laser pulse - ulse tacker (Macro-pulse) + Micro-pulse preparation 15~20-ps temporal shaping with pulse stacking could generate quare pulse!! Its flatness of the plateau depends on optimization of micro pulses!! reparation & Characterization of micro-pulse (2~5 ps) It s s very fine to shape : You have to exactly measure the shape of aimed laser pulse. Grating compressor: : It s s characterized by IDER (8). rism-pair pair: : It s s characterized by Cross Correlator (AL). Adaptive DAZZLER(AO): It s s characterized by itself (Fastlite). For 3D-laser pulse shaping, the complex system with adaptive DAZZLER & adaptive Deformable Mirror might have a lot of possibilities with fine tuning. For arbitrary 3D-laser pulse shaping, the complex system with adaptive ilica-lm LM & adaptive DM should be the goal for any case. Especially, It can be utilized for multi- bunch beam shaping. A) Computer-aided ilica-lm (patial Light Modulator) Rectangular ulse shaping (Arbitrary hape) B) Computer-aided DM (Deformable mirror) Flattop spatial profile (Arbitrary hape) LM Automatic Control Optics patial shaping (DM) ulse shaping (LM) Wave front Control (DM) DM ))) 2 ~ 12 ps Fundamental 2 ~ 5 ps THG (263 nm)