Development of a high power chirped pulse amplification laser for driving secondary sources
Date
2019
Authors
Baumgarten, Cory M., author
Rocca, Jorge, advisor
Roberts, Jacob, committee member
Lee, Siu Au, committee member
Marconi, Mario, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Laser applications which require high energy ultrashort laser pulses have been limited in repetition rate. This dissertation describes the development of high repetition rate, high energy, all diode pumped ultrashort pulse Yb:YAG lasers and their use in two selected applications. Yb:YAG is an attractive gain medium for high average power, ultrashort pulse laser operation. This material, with long upper level lifetime, is well suited for direct pumping by high power, narrow bandwidth laser diodes, and combined with a small quantum defect, minimal heating of the material is produced. Additionally, the thermal conductivity and optical properties of Yb:YAG dramatically improve when cooled to cryogenic temperatures. The main focus of this dissertation is the development of an all diode-pumped, chirped pulse amplification, ultrashort pulse laser based on a cryogenically-cooled Yb:YAG amplifier design. This laser system operates at λ = 1.03 μm and is capable of producing 1.4 J pulses before compression at 500 Hz and 1 kHz repetition rate. During 500 Hz operation, the laser used a combination of room temperature and cryogenically-cooled Yb:YAG amplifiers to generate pulses of 1 J energy compressed to sub- 5ps duration. At 1 kHz, pulse energies of 1 J with sub-10ps transform limited pulse durations were obtained. The simultaneously high pulse energies and repetition rates obtained in this work will be beneficial for a host of applications including tabletop sources of coherent short wavelength radiation, high power femtosecond sources operating in the near and mid-infrared, and high gradient laser plasma accelerators. The work in this dissertation specifically demonstrates the use of cryogenically cooled Yb:YAG lasers in the development of soft x-ray lasers and a near-infrared optical parametric amplifier for the testing damage threshold of multilayer coatings.The generation of coherent radiation in the soft x-ray regime was historically limited to 10 Hz. Compact, table-top soft x-ray lasers have enabled a range of applications including nano- scale imaging and lithography, the investigation of hot dense plasmas, and nano-scale fabrication. Recently, compact sources of coherent soft x-ray laser radiation were demonstrated at repetition rates of one hundred shots per second using the laser technology described in this dissertation. As a demonstration of the Yb:YAG laser's excellent beam quality and high average power, this system was used to pump a high repetition rate soft x-ray laser. The optical pump laser and the resulting soft x-ray laser, operated at a record 400 Hz repetition rate with strong lasing in the λ = 18.9 nm line of Ni-like Mo. This work also demonstrates a Yb:YAG laser driven, optical parametric chirped pulse amplification (OPCPA) laser system operating at 100 Hz in the near-infrared, which was used to per- form laser induced damage threshold measurements of optical coatings. OPCPAs have emerged as a next generation ultrafast laser source for generating sub-femtosecond laser pulses useful for probing molecular electron dynamics as well as creating ultra-intense, femtosecond laser pulses for exploring exotic states of matter and for the development of next generation laser plasma accelerators. The OPCPA developed as part of this work operates at wavelengths ranging from λ = 1.5-2 μm with final amplification stages pumped at 100 Hz with a chirped pulse amplification laser based on cryogenically-cooled Yb:YAG. The OPCPA was used to obtain damage thresholds of optical coatings in what to our knowledge constitutes the first results of picosecond damage performed in this wavelength range.
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Subject
diode
Yb:YAG
lasers
cryogenic