Mid-infrared Optical Parametric Amplification Research Articles

Investigation on Characteristics of 3–5 μm Mid-Infrared Optical Parametric Amplification in LiInS2

Investigation on Characteristics of 3–5 μm Mid-Infrared Optical Parametric Amplification in LiInS₂

Simultaneously Wavelength- and Temperature-Insensitive Mid-Infrared Optical Parametric Amplification with LiGaS2 Crystal

Ultrafast mid-infrared (mid-IR) lasers with a high pulse repetition rate are in great demand in various fields, including attosecond science and strong-field physics. Due to the lack of suitable mid-IR laser gain medium, optical parametric amplifiers (OPAs) are used to generate an ultrafast mid-IR laser. However, the efficiency of OPA is sensitive to phase mismatches induced by wavelength and temperature deviations from the preset points, which thus limits the pulse duration and the average power of the mid-IR laser. Here, we exploited a noncollinear phase-matching configuration to achieve simultaneously wavelength- and temperature-insensitive mid-IR OPA with a LiGaS2 crystal. The noncollinearity can cancel the first-order dependence of phase matching on both wavelength and temperature. Benefitting from the thermal property of the LiGaS2 crystal, some collinear phase-matching solutions derived from the first-order and even third-order wavelength insensitivity have comparatively large temperature bandwidths and can be regarded as approximate solutions with simultaneous wavelength and temperature insensitivity. These simultaneously wavelength- and temperature-insensitive phase-matching designs are verified through numerical simulations in order to generate few-cycle, high-power mid-IR pulses.

Numerical study on mid-infrared optical parametric amplification around 5 µm by injecting signal vector beams in As2Se3 MOFs

The influence of the core diameter and pump wavelength on the phase-matching conditions when different signal vector beams are injected is analyzed numerically in a suspended-core ${{\rm As}_2}{{\rm Se}_3}$As2Se3 microstructured optical fiber (MOF). The idler wavelengths satisfying the phase-matching conditions with different signal vector beams can reach wavelengths of 4.8–5.9 µm in the ${{\rm As}_2}{{\rm Se}_3}$As2Se3 MOFs with different core diameters. By changing the signal vector mode field and adjusting the corresponding signal wavelength, the idler wavelength can be tuned in 754.8 nm from 4.9182 to 5.6730 µm with the pump wavelength changing from 2.80 to 2.90 µm. The influence on signal gain and the idler conversion efficiency is calculated in the ${{\rm As}_2}{{\rm Se}_3}$As2Se3 MOFs with different lengths when injecting different signal vector beams. The peak gain of signal and idler conversion efficiency can reach $\sim{28}\,\, {\rm dB}$∼28dB and $\sim{24}\% $∼24%, respectively, when the different signal vector beams are injected. The simulated results demonstrate that the optical parametric oscillation with wavelengths longer than 5 µm can be realized in chalcogenide fibers with signal vector beam injection.

91.1 kW, 5.3 ns compact mid-infrared optical parametric amplification based on PPMgLN

We report a compact mid-infrared optical parametric oscillator (OPO) seeded optical parametric amplifier (OPA) based on PPMgLN. The pump for the OPO and OPA is a split 1064 nm electro-optical Q-switched Nd:YAG laser with a pulse width of 11.7 ns and a pulse repetition frequency of 2 kHz. The idler power of 116 mW of the OPO is used for the OPA seed. Under the incident pump power of 7.36 W and the crystal temperature of 30 °C, the idler power of the OPA is 966 mW with a pulse width of 5.3 ns, corresponding to a conversion efficiency of 11.5% and a calculated peak power of 91.1 kW. The central wavelength of the OPA idler is 3731.2 nm with a linewidth of 8.8 nm at 30 °C, and decreased from 3748.8 nm to 3704.0 nm when the crystal is heated from 20 to 45 °C. The beam quality factors of the OPA are 3.4 and 3.7 in the horizontal and vertical directions, respectively.

Theoretical investigations of broadband mid-infrared optical parametric amplification based on a La3Ga5.5Nb0.5O14 crystal.

Recent progress in strong-field physics has stimulated the quest for intense mid-infrared ultrashort light sources. Optical parametric amplification (OPA) is one promising method to build up such sources, however, its development significantly relies on the availability of suitable nonlinear crystals. Here, we introduce a positive uniaxial crystal La3Ga5.5Nb0.5O14 (LGN), which exhibits a favorable set of optical properties for the application in a mid-IR OPA. We theoretically evaluate the performance of LGN as the nonlinear crystal of a mid-infrared OPA, with an emphasis on the bandwidth characteristic. We find that this crystal can support broadband amplifications across its entire mid-infrared transparent region up to 6 μm, outperforming other commonly-used mid-infrared crystals in terms of gain bandwidth. Few-cycle mid-infrared pulses at various wavelengths can be generated from the LGN-based optical parametric chirped-pulse amplifiers.

High-power and widely tunable mid-infrared optical parametric amplification based on PPMgLN.

We report on a high-power and widely tunable optical parametric amplifier (OPA) based on PPMgLN and pumped by a pulsed 1.064μm MOPA laser. The operating wavelength of the OPA system is continuously tunable from 2.68 to 3.07μm by adjusting the temperature of PPMgLN crystals, with average output power varying from 74.6 to 66.7W for 310W of pump power, corresponding to an optical-to-optical conversion efficiency of ∼22.8% at 2.68μm and ∼20.5% at 3.07μm, respectively. Output beam quality factor (M2) of the OPA was measured to be <4 over the whole tuning range.