A narrowband infrared source based on orientation-patterned GaAs for standoff detection of chemicals

Abstract

This paper presents our work on a pulsed single-frequency tunable optical parametric oscillator based on orientation-patterned gallium arsenide. Owing to crystal temperature tuning, this source covers the 10.2-11.2 and 7.6-8.6 μm ranges in singlelongitudinal mode operation with a linewidth below 30 MHz. Standoff detection of ammonia around 10.35 and 10.5 μm is performed by implementing this source in an Integrated Path Differential Absorption Lidar (IP-DIAL) setup.

Actively Q-switched tunable single-longitudinal-mode 2 µm Tm:YAP laser using a transversally chirped volume Bragg grating

“…Therefore, increasing our tuning range would require some additional work from the supplier or using a different approach. After down conversion by the NesCOPO, this 20 nm tuning range translates to 360 nm around 8 µm and to 500 nm tuning around 10 µm, which is enough to scan different absorption bands of several hazardous chemicals [3]. The SLM operation we demonstrated with less than 4 pm linewidth is nearly Fourier transform limited and outperforms all that was already demonstrated with pulsed tunable 2 µm lasers.…”

“…For an amplification factor of 10, a laser energy of 200 to 250 µJ per pulse at 2 µm with a pulse duration between 10 and 100 ns is targeted. Besides, a higher average power and a higher pulse repetition rate are desirable for both facilitating wavelength using commercial spectrometers, as well as for using the NesCOPO as a source for stand-off detection of fast-moving gas plumes or in the presence of atmospheric fluctuations [3]. We built a second version of the laser operating at 300 Hz and successfully used it to pump an OP-GaAs NesCOPO.…”

Optical parametric sources from the SWIR to the LWIR for standoff gas sensing

“…5). Nonetheless the NesCOPO could be arbitrarily tuned to any desired wavelength by combining piezoelectric actuation and temperature control, the spectral purity was almost Fourier-transform-limited, and a spectrum of ammonia near 10.4 µm was recorded [22]. One of the positive outcomes of these experiments involving the first version of the Tm:YAP laser was the very good reproducibility of the results over the years, secured by the long lifetime of components in the infrared and the good opto-mechanical implementation made by the partner company.…”