Few-cycle fs-pumped NOPA with passive ultrabroadband spectral shaping

Abstract

A compact, femtosecond-pumped noncollinear optical parametric amplifier (NOPA) is presented with a passive spectral shaping technique, employed to produce a flat-top-like ultrabroadband output spectrum. The NOPA is pumped by a dedicated 2 mJ, 120 fs Yb3+-based CPA system, which generates both the second harmonic pump pulse and white light supercontinuum as the signal pulse. A chirped mirror pair pre-compensates the material GVD within the optical path of the signal pulse to produce a near-FTL pulse duration at the OPA crystal output. By optimizing both the pump/signal cross angle and the pump/signal delay, the 40 cm × 40 cm footprint, single-pass, fs-pumped, direct NOPA (non-NOPCPA) system generates a record 20 µJ, 11 fs pulses at 820 nm central wavelength with a bandwidth of 230 nm FWHM, to be used as an ultrashort optical probe pulse for relativistic laser-plasma interactions at the petawatt-class POLARIS laser system.

Optical probing of ultrafast laser-induced solid-to-overdense-plasma transitions

“…The plasma dynamics are investigated by longitudinally irradiating a -extended region of the interaction with -polarized broadband ( centered at under an incidence angle of ) and -energy probe pulses produced in a Non-collinear Optical Parametric Amplifier (NOPA) 54 . When optimally compressed, the probe pulses have a duration of .…”

High-performance 800–1050 nm seed pulses based on spectral broadening and filtering for petawatt lasers

“…Note that as high as 250 μJ pulses with a high temporal contrast and broadband spectrum were generated from a single-stage four-wave mixing (FWM) process in 2019 [ 9 ] . The second category is based on Yb femtosecond laser pulses with a relatively narrow spectrum at 1030 nm central wavelength [ 10 , 11 ] . In comparison to the Ti:sapphire laser, the Yb femtosecond laser has better energy stability and long-term operation reliability, which have been widely verified in industry for years.…”

“…Through white-light generation, difference frequency generation and two stages of OPA processes, a 910 nm seed pulse with pulse energy of 80 μJ was obtained in 2017 [ 10 ] . More recently, a noncollinear OPA system pumped by a Yb 3+ -based chirped pulse amplification (CPA) system was presented to generate 11 fs pulses with 230 nm full width at half maximum (FWHM) bandwidth [ 11 ] . Apparently, multiple stages of complicated nonlinear processes were used in most of the reported methods to generate broadband seed pulses with a considerable temporal contrast.…”