Broadband and tunable optical parametric generator for remote detection of gas molecules in the short and mid-infrared

Abstract

The development of a novel broadband and tunable optical parametric generator (OPG) is presented. The OPG properties are studied numerically and experimentally in order to optimize the generator's use in a broadband spectroscopic LIDAR operating in the short and mid-infrared. This paper discusses trade-offs to be made on the properties of the pump, crystal, and seeding signal in order to optimize the pulse spectral density and divergence while enabling energy scaling. A seed with a large spectral bandwidth is shown to enhance the pulse-to-pulse stability and optimize the pulse spectral density. A numerical model shows excellent agreement with output power measurements; the model predicts that a pump having a large number of longitudinal modes improves conversion efficiency and pulse stability.

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

“…The performance of this system is typically limited by the level of received laser power, which is dependent on the incident laser power, distance between receiver and scattering target, type of scattering materials, and size of the receiver aperture [142][143][144]. High-power and broadband tuning lasers, such as OPO and EC-QCLs, are desired to achieve a higher signal-to-noise ratio (SNR) [145][146][147]. However, high-sensitive and low-noise detectors are particularly important for applications in public areas where eye safety should be considered.…”

Airborne pipeline leak detection: UV or IR?

“…The IR absorption platform makes use of a Medium Wavelength Infrared (MWIR) laser source and a large aperture collecting telescope 10,11 (somewhat similar to the UV platform). The laser beam hits a sandblasted aluminum panel lying on the soil and thus does not penetrate the soil.…”

Differential optical absorption spectroscopy lidar for mid-infrared gaseous measurements

“…The OPG is pumped by an actively Q-switched Nd:YAG laser (1.064 μm, 700 ps at 10 kHz, multiple longitudinal modes) from BrightSolutions, model Wedge HF; the OPG is made of a multiple period PPMgO:LN (40 mm × 10 mm × 1 mm) from Covesion, model MOPO1-1.0-40. The OPG is described in detail in [17]. The repetition rate is variable from 1 Hz to 100 kHz.…”

“…A small portion of the beam would then be sent directly to the spectrograph. Ideally, one would use an imaging spectrograph and simultaneously monitor two spectra with the detection camera, the reference, and the open path spectra; but then the noncollinear amplification in the OPG output, in the presence of spatial filtering due to the imaging of the beam on the input slit of the spectrograph, can and will affect the recorded reference spectrum [17]. The reference spectrum would also correct for another source of error or noise: the spectral instability from pulse to pulse.…”

“…The reference spectrum would also correct for another source of error or noise: the spectral instability from pulse to pulse. In [17], we proposed to use a largely multiple longitudinal mode pump in order to generate an OPG emission that has a smooth and stable spectrum from pulse to pulse. This would minimize the need for the reference spectrum.…”