Parametric generation of energetic short mid-infrared pulses for dielectric laser acceleration

Abstract

Optical parametric amplifiers (OPAs) exploit second-order nonlinearity to transfer energy from a fixed frequency pump pulse to a variable frequency signal pulse, and represent an easy way of tuning over a broad range the frequency of an otherwise fixed femtosecond laser system. OPAs can also act as broadband amplifiers, transferring energy from a narrowband pump to a broadband signal and thus considerably shortening the duration of the pump pulse. Due to these unique properties, OPAs are nowadays ubiquitous in ultrafast laser laboratories, and are employed by many users, such as solid state physicists, atomic/molecular physicists, chemists and biologists, who are not experts in ultrafast optics. This tutorial paper aims at providing the non-specialist reader with a self-consistent guide to the physical foundations of OPAs, deriving the main equations describing their performance and discussing how they can be used to understand their most important working parameters (frequency tunability, bandwidth, pulse energy/repetition rate scalability, control over the carrier-envelope phase of the generated pulses). Based on this analysis, we derive practical design criteria for OPAs, showing how their performance depends on the type of the nonlinear interaction (crystal type, phase-matching configuration, crystal length), on the characteristics of the pump pulse (frequency, duration, energy, repetition rate) and on the OPA architecture.

Parametric generation and characterization of femtosecond mid-infrared pulses in ZnGeP_2

“…The 3.47-µm OPG is then stretched in a 5-mm-thick germanium plate, enabling selective amplification of different portions of the OPG spectrum in the subsequent OPA by adjusting the seed-pump delay. OPGs exhibit temporal incoherence; however, the coherence is enhanced subsequent to OPG by chirping the OPG pulse and selecting a small temporal/spectral portion of the stretched OPG pulse for frequency mixing in the first OPA [28]. The stretcher also serves to block any residual pump energy and improve parametric amplification of the seed in the first OPA stage.…”

Generation of high-energy narrowband 205 μm pulses for seeding a Ho:YLF laser

“…To significantly increase center photon energy and bandwidth of high harmonics for generating shorter attosecond or even zeptosecond X-ray pulses, the development of highenergy few-cycle pulses farther into the mid-IR is in demand. Rapid progress has been made on the generation of highenergy short-pulse mid-IR laser sources above 3 μm [23][24][25][26][27][28][29]. However, the spectral bandwidth has not reached one octave, which limits the pulse duration to multicycle.…”

Bandwidth Control in 5-µm Pulse Generation by Double-Chirped Optical Parametric Amplification

“…In this paper, we describe the development and performance of a mid-IR laser system capable of delivering short (femtosecond to picosecond) mid-IR laser pulses via optical parametric amplification (OPA) and examine the effect of pump and seed chirp on the generated idler spectral bandwidth through numerical modeling and experimentation. A two-stage optical parametric generator (OPG)/OPA design based on ZGP crystals pumped in the mid-IR spectral region [15] has been modified to produce bandwidth-tunable femtosecond laser pulses near 5 μm with μJ-level pulse energies and high shot-to-shot energy stability. The temporal profile of these mid-IR pulses is fully characterized using cross correlation that employs a standard silicon-based charge-coupled device (CCD).…”