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Current Situation of Yb:YAG Laser at A1 Ground Laser Hut

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Presentation on theme: "Current Situation of Yb:YAG Laser at A1 Ground Laser Hut"— Presentation transcript:

1 Current Situation of Yb:YAG Laser at A1 Ground Laser Hut
SuperKEKB Injector Laser RF Gun Workshop Rui Zhang ACCL Division V, RF-Gun Group Jun 10, KEK

2 Outline Yb:YAG thin disk regenerative amplifier
Configuration and results Problems and next step work Low temperature Yb:YAG thin disk laser Preparatory work and results Problems Solution and next step work Novel bonding method for thin disk laser head Background Experimental setup introduction Summary A1 ground Yb:YAG laser system 2 of 13

3 Current layout of A1 ground laser system
Repetition frequency MHz Wavelength selection 1030nm & 1064 nm Repetition frequency 10 MHz Grating stretcher (Transmission) SOA pulse picker Yb single mode fiber amp nm ANDi type oscillator Menlo 1030 nm oscillator (commercial) Yb-doped double clad fiber amp 1064 nm ASE rejection grating pair 1030nm EO module pulse picker Yb-doped PCF fiber amp 10 Hz New Yb PCF fiber amplifier for Yb:YAG regenerative amplifier 1064 nm Yb:YAG thin disk regenerative amplifier Nd:YAG regenerative amplifier nm nm A1 ground Yb:YAG laser system 3 of 13

4 I. Yb:YAG thin disk regenerative amplifier
For picosecond and nanosecond laser pulse, the regenerative amplifier is very powerful Strong amplification factor can help relieve stress of multi-pass amplifier stages and reduce thermal effect New dichroic mirror with high optical quality and high damage threshold (this March) Additional Yb PCF amplifier A1 ground Yb:YAG laser system 4 of 13

5 I. Yb:YAG thin disk regenerative amplifier
400 ns Seed laser pulse is trapped and amplified inside the cavity Accompanied self oscillation (balance for gain competition between cavity oscillation and seed laser amplification)  Moderate amplification before injection into regenerative amplifier (Part II) Stability (thermal effect induced de-polarization and cavity mode change) high quality thin disk laser head and low temperature laser operation (Part II & III) A1 ground Yb:YAG laser system 5 of 13

6 II. Low temperature Yb:YAG thin disk laser
Low temperature laser operation feasibility analysis Available high gain is possible Low amplified spontaneous emission (ASE) Simpler and more stable (compare with cryogenic laser) Moderate amplification before regenerative amplifier Current low temperature laser operation at A1 ground laser hut Peltier cooling plates: Controllable temperature from 23 oC to -36 oC Small vacuum chamber Home made laser soldering laser head A1 ground Yb:YAG laser system 6 of 13

7 II. Low temperature Yb:YAG thin disk laser
Gain test at different temperature and wavelength Home made tunable seed laser Face pump and seed laser edge injection Seed laser Amplified laser Pump laser Face pump and edge injection A1 ground Yb:YAG laser system 7 of 13

8 II. Low temperature Yb:YAG thin disk laser at different temperature
Amplification factor against wavelength at different temperature A1 ground Yb:YAG laser system 8 of 13

9 II. Problems for low temperature Yb:YAG thin disk laser
Damage of soldering thin disk laser head Bigger temperature gap for low temperature laser operation Serious residual stress introduced by soldering Thermal expansion coefficient mismatch between copper head and Yb:YAG thin disk A1 ground Yb:YAG laser system 9 of 13

10 II. Solution for laser head damage
Comparison between Yb:YAG, CuW and Cu Yb:YAG Cu10W90 Cu15W85 Copper Thermal conductivity (W/m/K) 11 190 200 396 Thermal expansion coefficient (10-6/K) 6.8 6.3 7.0 16.4 Cu15W85 is an excellent candidate to solve mismatch problem Small mismatch ensures the stability and durability of Yb:YAG thin disk and Au-Sn soldering layer Cu15W85 heatsinks are preparing and will be tested recently after soldering with Yb:YAG thin disks A1 ground Yb:YAG laser system 10 of 13

11 III. Novel bonding method for thin disk laser head
Introduced residual stress by soldering is unavoidable (heating) Ambient temperature bonding is suggested Atomic level contact for different materials Without any residual stress Direct bonding without intermediate Proven technique Suitable to thin disk laser configuration Principle of ambient bonding* * No.7, Page 31, Modern Chemistry, July 1998. A1 ground Yb:YAG laser system 11 of 13

12 III. Novel bonding method for thin disk laser head
Ambient bonding technique has attracted attention all over the world Work together with other research groups for high quality bonding samples (from this summer) Institute for Molecular Science: Dr. Taira’s group (also for Nd:YAG stack sample) University of Tokyo It can be used for regenerative amplifier, low temperature and cryogenic laser and multi-pass amplifier for RF gun laser Bonding sample made by Chou Univ.1 Laser operation by use of ambient temperature bonding components at Osaka Univ.2 21a-S611-3, The 63 Spring Annual Meeting, Tokyo, JSAP. 21a-S611-2, The 63 Spring Annual Meeting, Tokyo, JSAP. A1 ground Yb:YAG laser system 12 of 13

13 Summary Yb:YAG thin disk regenerative amplifier Amplification achieved
Adjustment and optimization are in process of doing for laser injection from A1 ground laser hut for RF gun Low temperature Yb:YAG thin disk laser Test finished New CuW heatsink is under of manufacturing After soldering, amplification will be carried out Room temperature bonding for thin disk laser head Made a cooperative relationship with other research institutes test and preparation will be done for ground Yb:YAG laser system A1 ground Yb:YAG laser system 13 of 13


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