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Strecher, compressor and time structure manipulation

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Presentation on theme: "Strecher, compressor and time structure manipulation"— Presentation transcript:

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

2 Energy spread reduction using temporal manipulation
Energy spread of 0.1% is required for SuperKEKB synchrotron injection. Gaussian Square 5nC 10nC 15nC 20nC 5nC electron Primary beam for positron production t 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 Stretcher Yb PCF Amplifier Yb:YAG thin-disk Amplifier SHG 100 fs 30 ps

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

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

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

7 Simulation

8 Pulse picker & Stretcher
4μm l/2 Stretcher WDM coupler LD Pump SMF 51.98 MHz 1740 gooves/mm Transmission grating > 90% loss Pulse spectrum after the stretcher

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

10 1740-grooves/mm

11 Streak camera measurement at SHG stage
FWHM: 30ps

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

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

14 Vacuum Chamber

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

16 Problem Without CPA With 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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