Abstract
Cavity ringdown (CRD) spectroscopy is extended for the first time from its conventional optical-absorption mode of operation into the regime of coherent Raman spectroscopy. Continuous-wave (cw) stimulated Raman gain (SRG) spectra of the 2916.5-cm-1 ν1 rovibrational fundamental Raman band of methane (CH4) gas are measured, using tunable cw laser light at ∼ 1544 nm to probe ringdown decay from a rapidly swept optical cavity that is itself inside the cavity of a cw single-longitudinal-mode Nd:YAG ring laser operating at ∼ 1064.5 nm. The resulting change of ringdown decay rate is dependent on pump laser irradiance and is associated with Raman gain. Remarkably, such SRG-CRD resonances display ringdown times that are longer than in the off-resonance case, contrasting with the usual reduction of ringdown time associated with absorption and other loss processes.
Original language | English |
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Pages (from-to) | 1-5 |
Number of pages | 5 |
Journal | Applied Physics B: Lasers and Optics |
Volume | 83 |
Issue number | 1 |
DOIs | |
Publication status | Published - Apr 2006 |