Mid-IR laser systems are now widely used in a variety of applications. Cr2+:CdSe and Cr2+:ZnSe crystals are considered among the most promising active media due to the wide tuning range in the mid-IR range. However, they have a high thermooptic coefficient and lower thermal conductivity. These properties lead to strong thermal effects and limitations in power scaling. One solution is to use a MOPA configuration. A sophisticated mathematical model was developed to select the optimal parameters, taking into account the temperature variation in the crystal, the beam geometry, the luminescence lifetime dependence on temperature, the refractive index gradient, and its effect on the intensity profile. In this paper, we present a comparison of theoretical data and experimental values according to the developed model. The comparison demonstrated the validity of the simulation results and the ability to use the model to calculate the optimal MOPA system configuration.
GaSe crystals that are promising as nonlinear optical converters in the mid- and far-infrared ranges are charac- terized by high Fresnel losses leading to transmittance per surface at the level of 77%. In this study, antireflection microstructures (ARMs) were fabricated on the surface of the GaSe single crystal by single-pulse femtosecond laser ablation. This method makes it possible to increase the transmission up to up to 92%.
We study the operating speed of high-speed photodetector based on GaSb/GaInAsSb/GaAlAsSb heterostructure with frontal bridge contact depending on the wavelength, radiation power, and bias voltage. The ultra-fast fiber lasers and high-speed oscilloscope were used for measurements.
We simulate supercontinuum generation in a fiber pumped by noise-like laser pulses for possible use in mid-IR spectroscopic breath analysis. The study uses a commercially available InF3 ZBLAN fiber and a Tm-doped all-fiber passively mode-locked laser. The supercontinua are modeled with input laser parameters in two different generation regimes with an average power of 560 mW and pulse durations of 300 and 800 fs. The maximum numerically achieved spectrum extends from 1 to 8.4 μm.
Currently, lasers are widely used for surgery, medical diagnostics and oncology research. Unfortunately, most of the used laser sources have a significant drawback - the lack of operating wavelength tuning possibility, which imposes significant limitations on the investigation of biological tissues spectral properties and searching for the optimal mode of their treatment. Comparison between different promising mid-IR sources was made. We report on development of mid-infrared (mid-IR) tunable lasers based on the Cr2+:CdSe single-crystals. These lasers operate in CW mode with the maximum output power of up to 2 W and possible tuning range from 2.2 to 3.6 μm.
Fiber Bragg grating (FBG) strain sensors are powerful tools for structural health monitoring applications. However, FBG sensor fabrication and packaging processes can lead to a non-linear behavior, that affects the accuracy of the strain measurements. Here we present a novel nondestructive calibration technique for FBG strain sensors that use a mechanical nanomotion transducer. A customized calibration setup was designed based on dovetail-type slideways that were mechanized using a stepping motor. The performance of the FBG strain sensor was investigated through analysis of experimental data, and the calibration curves for the FBG strain sensor are presented.
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