High-Average-Power Optical Parametric Chirped Pulse Amplification Development for the Linac Coherent Light Source II
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Authors
Windeler, Matthew
Date
Type
thesis
Language
eng
Keyword
Nonlinear Optics , Photonics , Optical Parametric Chirped Pulse Amplification
Alternative Title
Abstract
X-ray free-electron lasers (FELs) have provided the highest brightness source for x-rays since the Linac Coherent Light Source (LCLS) began lasing in 2009. Upgrades to the LCLS accelerator driving the x-ray FEL will increase the pulse repetition rate from 120 Hz to the kilohertz regime, with a maximum of 1 MHz, opening the door for experiments previously impossible due to poor signal-to-noise. Many experiments use an additional, ultrafast laser in a pump-probe configuration, either for sample excitation or probing the sample excited by the x-ray beam. User needs span the electromagnetic spectrum from ultraviolet to the mid-infrared. Many of the nonlinear processes for generating such radiation have low conversion efficiency. Thus, a new tunable light source capable of operating at high repetition rates with large pulse energies is required to complement the upgrades to the x-ray FEL. The chosen light source is an optical parametric chirped pulse amplifier (OPCPA). This mitigates the thermal effects that need to be controlled at high average powers in the amplification gain medium. Two operational modes have been developed: a near infrared (NIR) and infrared (IR) mode. The NIR OPCPA system operates at 100 kHz, sub-20 fs pulse duration, delivering 88.6 W average power at a center wavelength of 800 nm. The seed pulses are derived from the pump laser via white-light continuum generation and are amplified in three non-collinear beta-barium borate stages (BBO). The final two high power stages are pumped with a 661 W Yb:YAG InnoSlab amplifier. The highpower IR OPCPA mode uses the nonlinear optical crystal potassium titanyl arsenate (KTA) and operates with tunable center wavelengths from 1.5 µm to 2.0 µm. Using a three-stage amplification scheme and the same kW-level InnoSlab Yb:YAG pump amplifier for the final non-collinear KTA stage, we demonstrate an amplified average
output power of 106.2 W at a center wavelength of 1.75 µm and 100 kHz. Idler absorption introduces a potential upper limit on the average power scaling for center wavelengths <1.70 µm. In addition to the development of the OPCPA, nonlinear optical processes at high average powers are also developed in order to provide large wavelength coverage. Future work will see the replication of the OPCPA system with LCLS-II.
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ProQuest PhD and Master's Theses International Dissemination Agreement
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International