Reducing wavelength jitter in white-light seeded femtosecond optical parametric chirped-pulse amplifiers

Abstract

White light generation (WLG) in bulk material can be used as a versatile broadband seed source for optical parametric chirped pulse amplification (OPCPA) stages. In this case, it is beneficial to optimize the performance of the WLG seeder in combination with the subsequent OPCPA stage. Here, we characterize how small variations in the drive pulse energy affect the white light seeder performance, in particular the wavelength stability of the amplified OPCPA spectrum. To isolate the influence of drive pulse energy on the OPCPA central wavelength, we introduce a phase-sensitive amplitude measurement and carefully optimize the drive pulse focus position (at the bulk) to minimize the sensitivity to the jitter of the drive pulse energy. With additional active stabilization of the delay between pump and seed pulses in the OPCPA, we achieve a central wavelength jitter of 2 × 10−4. With this performance, our source is an ideal front-end for applications in laser-plasma acceleration or free-electron laser seeding.