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Proceedings Paper

Design of a tunable mid-IR OPO source for DIAL detection of trace gases
Author(s): A. T. Reghunath; Purnima Malhotra; Yogesh Kumar; Bharat Bhushan
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Paper Abstract

The design of an efficient optical parametric oscillator (OPO) tunable in the range of 2.3 to 4.5 micron, as LIDAR source, for sensitive, selective and rapid remote detection and measurement of atmospheric trace gases at ranges upto 5 km is described. Potassium Titanyl Arsenate (KTA) a nonlinear crystal, having good transmission from 350 to 5000 nm is proved to be most suitable for this application. Tuning is achieved by angle tuning in critical phase matching of type II in X-Z plane, by changing the propagation direction from about 41 to 49 degrees with the Z-axis, when pumped with Nd:YAG laser at 1064nm. The expected linewidth of KTA OPO in the absence of any wavelength selective device is found to vary from 10 to 110 cm-1 which reduces to 0.1 cm-1 on introduction of an intracavity grating at grazing incidence. Using a 600 l/mm grating, with the tuning mirror fixed on a commercially available fast rotation stage, random tuning to any desired wavelength can be achieved in 40 ms. Threshold of optical parametric oscillation is found to vary from 2 to 3 J/cm2 as the idler wavelength varies from 2.3 to 4.5 micron. With this limitation, the pump energy requirement varies from 450 mJ to 600 mJ for 20 mJ output energy at different wavelengths in singly resonant oscillator configuration. Tuning arrangement for rapid tuning of output to lambdaon and lambdaoff wavelengths of different chemical species for DIAL detection is described.

Paper Details

Date Published: 12 December 2006
PDF: 11 pages
Proc. SPIE 6409, Lidar Remote Sensing for Environmental Monitoring VII, 64091B (12 December 2006); doi: 10.1117/12.697916
Show Author Affiliations
A. T. Reghunath, Laser Science and Technology Ctr. (India)
Purnima Malhotra, Laser Science and Technology Ctr. (India)
Yogesh Kumar, Laser Science and Technology Ctr. (India)
Bharat Bhushan, Laser Science and Technology Ctr. (India)


Published in SPIE Proceedings Vol. 6409:
Lidar Remote Sensing for Environmental Monitoring VII
Upendra N. Singh; Toshikazu Itabe; D. Narayana Rao, Editor(s)

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