| 摘要 |
The present invention is directed to methods and apparatus for detecting species in a laser cavity. According to one preferred embodiment, a device according to the invention includes: a source of excitation energy at a first wavelength; a first optic fiber; a resonant cavity; an absorption element; and a detector element. The first optic fiber has at least a first portion which is lasant-doped, and is optically coupled to the excitation source. The doping causes the first optic fiber to amplify light. Thus, in response to light coupled from the excitation source, the first optic fiber is capable of lasing. The resonant cavity surrounds the first portion of the optic fiber and has at least a first wavelength-specific reflector, such that laser light at only a second wavelength is amplified in the cavity. The absorption element can expose a sample to the light contained within the resonant cavity. The detector is optically coupled to the resonant cavity. It detects variations in the intensity of the laser light within the resonant cavity. By detecting variations in the intensity of the light in the cavity, the detector can indicate the presence of particular species.
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