Efficient generation of few-cycle pulses beyond 10 μm from an optical parametric amplifier pumped by a 1-µm laser system

Nonlinear vibrational spectroscopy profits from broadband sources emitting in the molecular fingerprint region. Yet, broadband lasers operating at wavelengths above 7 μm have been lacking, while traditional cascaded parametric frequency down-conversion schemes suffer from exceedingly low conversion efficiencies. Here we present efficient, direct frequency down-conversion of femtosecond 100-kHz, 1.03-μm pulses to the mid-infrared from 7.5 to 13.3 μm in a supercontinuum-seeded, tunable, single-stage optical parametric amplifier based on the wide-bandgap material Cd0.65Hg0.35Ga2S4. The amplifier delivers near transform-limited, few-cycle pulses with an average power > 30 mW at center wavelengths between 8.8 and 10.6 μm, at conversion efficiencies far surpassing that of optical parametric amplification followed by difference-frequency generation or intrapulse difference-frequency generation. The pulse duration at 10.6 μm is 101 fs corresponding to 2.9 optical cycles with a spectral coverage of 760–1160 cm−1. CdxHg1−xGa2S4 is an attractive alternative to LiGaS2 and BaGa4S7 in small-scale, Yb-laser-pumped, few-cycle mid-infrared optical parametric amplifiers and offers a much higher nonlinear figure of merit compared to those materials. Leveraging the inherent spatial variation of composition in CdxHg1−xGa2S4, an approach is proposed to give access to a significant fraction of the molecular fingerprint region using a single crystal at a fixed phase matching angle.Peer Reviewe

Narrow-bandwidth mid-infrared optical parametric generator based on HgGa2S4 crystal pumped by 16-ps pulses at 1064 nm

Pumping with 16-ps long, 15 μJ pulses, we report on extremely wide tuning range in the mid-IR and narrow-band, close to Fourier limit, operation of an injection-seeded HGS OPG

Magnitude of the nonlinear coefficients of the monoclinic crystal BaGa4Se7

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Phase-Matching Properties of the Monoclinic Crystal BaGa4Se7

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Magnitude of the nonlinear coefficients of the monoclinic crystal BaGa4Se7

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Magnitude and Relative Sign of the Quadratic Nonlinear Coefficients of the BGSe Monoclinic Acentric Crystal

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Magnitude and Relative Sign of the Quadratic Nonlinear Coefficients of the BGSe Monoclinic Acentric Crystal

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Optical damage studies of mercury thiogallate nonlinear crystals for use in 1-μ m pumped optical parametric oscillators

We investigated optical damage (surface and bulk) in one of the most promising wide bandgap nonoxide nonlinear crystals, HgGa2S 4, that can be used in ~1-μ m pumped optical parametric oscillators (OPOs) and synchronously pumped OPOs (SPOPOs) for generation of idler pulses above 4 μ m without two-photon absorption losses at the pump wavelength. The optical damage has been characterized at the pump wavelength for different repetition rates using uncoated and antireflectioncoated (mainly with a single layer for pump and signal wavelengths) samples. HgGa2S 4 is the most successful nonlinear crystal (both in terms of output energy and average power) for such OPOs, but optical damage inside the OPO has a lower threshold and represents at present the principal limitation for the achievable output. It is related to peak pulse and not to average intensity, and bulk damage in the form of scattering centers occurs before surface damage. Such bulk damage formation is faster at higher repetition rates. Lower repetition rates increase the lifetime of the crystal but do not solve the problem. The safe pump fluence in extracavity measurements is © 2013 SPIE

New Ba-Based Crystals for Nonlinear Frequency Conversion in the Mid-IR

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