초록 ▼

A device of detection of gas in trace amounts by a semiconductor laser coupled to a resonant optical cavity containing a chemical species to be analyzed. The device comprises a resonant optical cavity containing a chemical species to be analyzed; a semiconductor laser, coupled by optical feedback to

A device of detection of gas in trace amounts by a semiconductor laser coupled to a resonant optical cavity containing a chemical species to be analyzed. The device comprises a resonant optical cavity containing a chemical species to be analyzed; a semiconductor laser, coupled by optical feedback to the optical cavity and capable of being frequency-scanned; a means for adjusting the laser-cavity coupling rate; a means for finely adjusting the optical feedback phase; and a means for measuring the light transmitted by the cavity.

대표청구항 ▼

The invention claimed is: 1. A device for detecting gas in trace amounts, comprising: a resonant optical cavity containing a chemical species to be analyzed; an optical feedback sensitive laser coupled by optical feedback to the resonant optical cavity and capable of being frequency-scanned; a mean

The invention claimed is: 1. A device for detecting gas in trace amounts, comprising: a resonant optical cavity containing a chemical species to be analyzed; an optical feedback sensitive laser coupled by optical feedback to the resonant optical cavity and capable of being frequency-scanned; a means for adjusting a laser-cavity coupling rate to provide improved laser-cavity coupling; a means for finely adjusting the phase of the optical feedback; and a means for measuring the light transmitted by the cavity. 2. The device of claim 1, wherein the device comprises a means for roughly adjusting the distance from the optical feedback sensitive laser to the resonant optical cavity. 3. The device of claim 1, wherein the means for finely adjusting the phase of the optical feedback is a means for setting a laser-cavity optical distance. 4. The device of claim 3, wherein the means for finely adjusting the phase of the optical feedback is a mirror disposed on a piezo-electric ceramic arranged in the optical path from the optical feedback sensitive laser to the resonant optical cavity. 5. The device of claim 1, wherein the means for adjusting the laser-cavity coupling rate is an optical attenuator attenuating the light sent back by the resonant optical cavity to the optical feedback sensitive laser. 6. The device of claim 1, wherein the optical feedback sensitive laser is a laser diode. 7. The device of claim 1, wherein the resonant optical cavity is of a V-shaped type, comprising a first mirror oblique with respect to a laser incidence direction, a second mirror orthogonal to the laser incidence direction, and a third mirror forming a cavity with the first and second mirrors. 8. The device of claim 1, wherein the resonant optical cavity is a conventional two-mirror cavity. 9. A method for using the device of claim 1, comprising the step of adjusting the ratio between a laser-cavity distance and a length of one or several arms of the resonant optical cavity to an integer. 10. A method for using the device of claim 1, comprising the step of varying a laser-cavity optical path by a value on the order of the laser wavelength. 11. A device for detecting gas in trace amounts, comprising: a resonant optical cavity containing a chemical species to be analyzed; an optical feedback sensitive laser coupled by optical feedback to the resonant optical cavity and capable of being frequency-scanned; an optical attenuator for adjusting the laser-cavity coupling rate to provide improved laser-cavity coupling; a mirror disposed on a piezo-electric ceramic for finely adjusting the phase of the optical feedback; and a photodetector for measuring the light transmitted by the cavity. 12. A device for detecting gas in trace amounts, the device comprising: a resonant optical cavity containing a chemical species to be analyzed, the resonant oDtical cavity having several arms; an optical feedback sensitive laser disposed at a distance from the resonant optical cavity and coupled by optical feedback to the resonant optical cavity and capable of being frequency-scanned; a means for adjusting the laser-cavity coupling rate; a means for finely adjusting the phase of the optical feedback; and a means for measuring the light transmitted by the resonant optical cavity, wherein the ratio between the distance and a length of one or the several arms of the resonant optical cavity is adjusted to be an integer.