Solid state lasers applied to trace gas detection.

Laboratoire de
Photophysique Moléculaire

UPR 3361 CNRS

Webmaster N. Picqué
(Latest update: 1/1/2005)

Lasers and FTS.

Research:
Laser based trace gas detection

Solid-state lasers
A high-resolution time-resolved Fourier transform interferometer is combined with a multimode Cr⁴⁺:YAG laser for intracavity laser absorption spectroscopy (ICLAS) experiments. Atmospheric absorption spectra are recorded in the 1.5 µm region with a minimum detectable absorption coefficient equal to 8 x 10^-11cm^-1 Hz^-1/2.	Chamber with Cr⁴⁺:YAG laser pumped by a Nd:YVO₄laser
Cr⁴⁺:YAG oscillator	The broad gain bandwidth of the crystal allows a simultaneous spectral coverage at most equal to 38 nm. The laser tunability covers the 1360-1577 nm range. Water vapor detection domain extends from the 100 ppmv down to the 0.1 ppbv level.
	Cr²⁺:ZnSe laser in a vacuum chamber.
In the frame of a collaboration with E. Sorokin and I.T Sorokina (Vienna, Austria), intracavity laser absorption spectroscopy (ICLAS) with an evacuated Cr²⁺: ZnSe laser is performed with a high-resolution time-resolved Fourier transform interferometer with a minimum detectable absorption coefficient equal to 4 10^-9cm^-1 Hz^-1/2in the 2.5µm region. This represents the extreme limit presently reached in the infrared by ICLAS with Doppler limited resolution. The broad gain band of the crystal allows a spectral coverage at most equal to 125 nm, wide enough to see entire vibration bands. Weak CO₂bands observed up to now only in the Venus atmosphere are recorded for the first time in a laboratory. H₂O detection limit down to 0.9 ppbv is also demonstrated.
Other www pages of our group dealing with this theme: Laser-based trace gas detection: with semiconductor lasers with solid-state lasers
More details may be found in: Time-resolved Fourier transform intracavity spectroscopy with a Cr²⁺:ZnSe laser N. Picqué, F. Gueye, G. Guelachvili, E. Sorokin, I.T. Sorokina, Optics Letters, in press, 2005. Intracavity Cr⁴⁺:YAG laser absorption analyzed by time-resolved Fourier transform spectroscopy, F. Gueye, E. Safari, M. Chenevier, G. Guelachvili, N. Picqué Applied Physics B, in press, 2005.