Terawatt class space-time multiplexed chirped pulse amplification based Nd:glass laser system: development, performance characteristics and application

Abstract

Twin energetic sub-picosecond duration laser pulses have been generated in air using space-time multiplexed chirped pulse amplification based all Nd:phosphate glass laser system. Multiple beam-lets are generated using beam splitting prior to compression to reduce energy fluence on compressor gratings and to avoid vacuum compressor. Eight pass all reflective single grating half Martinez grating pulse stretcher and complimentary double pass mixed grating Treacy compressor has been setup to provide stretching/ compression factor of 6x103 for ~ 200 fs laser pulses at 1055 nm, to avoid excess optical nonlinearities during amplification and propagation through optical elements. Stretched laser pulse with energy of 150 pJ is amplified using regenerative and four-pass power amplifier with an output pulse energy exceeding 2 J at minimum shot to shot interval of 90 s. Amplified stretched pulses are compressed to full width in range from 450 fs to 900 fs at half maxima, with partial compensation of gain narrowing with spectral broadening owing to accumulated nonlinear phase. Various issues of pulse compression in mixed grating compressor are discussed. For demonstration purposes, laser pulses have been applied to study nonlinear properties and modification of optical materials in air.