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Strecher, compressor and time structure manipulation Xiangyu Zhou 20. Feb. 2015.

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Presentation on theme: "Strecher, compressor and time structure manipulation Xiangyu Zhou 20. Feb. 2015."— Presentation transcript:

1 Strecher, compressor and time structure manipulation Xiangyu Zhou 20. Feb. 2015

2 Energy spread reduction using temporal manipulation Gaussian Square 5nC 10nC 15nC 20nC 15nC 10nC 5nC 5nC electron 15nC Primary beam for positron production t t Energy spread of 0.1% is required for SuperKEKB synchrotron injection. When the charge distribution is uniform in a cylinder, the energy spread of the bunch is lower than the result of Gaussian charge distribution. For the laser source, the pulse width should be reshaped to rectangle structure.

3 Time structure of laser system Yb Oscilattor Yb PCF Amplifier SHGYb:YAG thin-disk Amplifier Stretcher 30 ps 100 fs

4 Grating Pair Stretcher and Compressor Compressor Stretcher Roof Mirror Short Wavelength Long Wavelength γθ Grating Phase Front Roof Mirror Lens Z Z -f ff Phase Front Positive GDD Negative GDD

5 Grating pair Transmission Grating Total Efficiency ~ 80% 85% Reflection Grating 95% Total Efficiency ~ 50%

6 Spectral Range Adjustment t Chirp t Spatially dispersed d For chirped pulse, the pulse shaping in the time domain can be controlled by adjusted the spectral shaping of the pulse. Spatial Masking

7 Simulation

8 Pulse picker & Stretcher  1740 gooves/mm Transmission grating Stretcher MHz LD Pump SMF WDM coupler 4μm Pulse spectrum after the stretcher > 90% loss

9 Pulse shaping Pulse shaping by streak camera Stretcher t t 1740-grooves/mm Telescope lens

10 1740-grooves/mm

11 Streak camera measurement at SHG stage FWHM: 30ps

12 CPA system Yb Oscilattor Yb PCF Amplifier Yb:YAG Thin-disk Amplifier SHG Pulse Shaping Adjustment Stretcher 2 ns Compressor 30 ps Yb Oscilattor Yb PCF Amplifier SHG Yb:YAG Thin-disk Amplifier Stretcher 30 ps 100 fs Yb Oscilattor Yb PCF Amplifier Yb:YAG Thin-disk Amplifier SHG Stretcher 2 ns Compressor 30 ps Yb Oscilattor Yb PCF Amplifier SHG Yb:YAG Thin-disk Amplifier Stretcher 30 ps 100 fs Pulse Shaping Adjustment Pulse Shaping Adjustment

13 Stretcher & Compressor FBG or Grating size is 18 cm for ns stretch

14 Vacuum Chamber

15 Slope injection at cathode 6mm(20ps) 9mm(30ps) Cathode 8mm 60° 4mm 6.92mm Original pulse shaping (Method-1) (Method-2) Grating Slit

16 Problem Without CPA Fiber amplifier limitation (mJ  ns) Spectral range adjustment is difficult With CPA Structure of stretcher and compressor is huge Transmission efficiency Damage threshold of gratings


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