초록 ▼

A sensitive fluid sensor for detecting fluids and particularly trace fluids. The sensor may be adjustable for detecting fluids of various absorption lines. To effect such adjustment, a tunable laser may be used. The laser may be an edge emitting diode, a VCSEL or other tunable source. The detection

A sensitive fluid sensor for detecting fluids and particularly trace fluids. The sensor may be adjustable for detecting fluids of various absorption lines. To effect such adjustment, a tunable laser may be used. The laser may be an edge emitting diode, a VCSEL or other tunable source. The detection apparatus of the sensor may incorporate a sample cell through which a laser light may go through. The sample cell may comprise a tunable ring-down cavity. The ring-down cavity may be a ring laser cavity like that of a ring laser gyroscope. There may be a photo detector proximate to the ring down cavity connected to a processor.

대표청구항 ▼

What is claimed is: 1. A fluid sensor comprising: a tunable light source; a cavity positioned to receive light from the tunable light source; and a detector positioned to receive light from the cavity; and wherein: the tunable light source is an edge emitting diode; and the edge emitting diode comp

What is claimed is: 1. A fluid sensor comprising: a tunable light source; a cavity positioned to receive light from the tunable light source; and a detector positioned to receive light from the cavity; and wherein: the tunable light source is an edge emitting diode; and the edge emitting diode comprises: a substrate; a layer, having a laser cavity with reflective surfaces situated at the edges of the laser cavity, situated on the substrate; and a moveable mirror proximate to one edge for tuning the laser cavity. 2. The sensor of claim 1, wherein the moveable mirror may be adjusted to tune the laser cavity to a particular wavelength. 3. A fluid sensor comprising: a tunable light source; a ring down cavity positioned to receive light from the tunable light source; and a detector positioned to receive light from the ring down cavity; and wherein: the tunable light source is a VCSEL; and the VCSEL comprises: a substrate; a first mirror situated on the substrate; an active area situated on the first mirror; and a second mirror situated at a variable distance from the first mirror. 4. The sensor of claim 3, wherein the variable distance may be adjusted to tune the VCSEL to a particular wavelength. 5. The sensor of claim 4, wherein the wavelength may be adjusted to determine the kind of fluid in the ring down cavity. 6. The sensor of claim 3, wherein the VCSEL further comprises: a current spreading layer on the active region; and an adjustable gap between the second mirror and the current spreading layer. 7. The sensor of claim 6, wherein the VCSEL further comprises: a first spacer situated between the first mirror and the active region; and a second spacer situated between the active region and the current spreading layer. 8. The sensor of claim 7, wherein the VCSEL further comprises a current confinement region situated at least partially in the current spreading layer. 9. The sensor of claim 8, wherein the VCSEL has an infrared bandwidth. 10. A fluid sensor comprising: a tunable light source; a ring down cavity positioned to receive light from the tunable light source; and a detector positioned to receive light from the ring down cavity; and wherein: the ring down cavity comprises: a containing structure; a first mirror positioned in the containing structure to receive light from the tunable light source; and at least another mirror positioned in the containing structure to receive light reflected by the first mirror arid reflect it back to the first mirror and vice versa for a plurality of times; the at least another mirror is moveable to adjust the wavelength of the containing structure; the light source is tuned to an absorption line of a fluid in the containing structure; the detector is proximate to the at least another mirror to detect light reflected in the containing structure; the ring down cavity is a ring laser cavity; the containing structure is tuned to an absorption line of the fluid in the containing structure; and the tunable light source is an edge emitting diode. 11. The sensor of claim 10, wherein the edge emitting diode comprises: a substrate; a layer, having a laser cavity with reflective surfaces situated at the edges of the cavity, situated on the substrate; and a moveable mirror proximate to one edge for tuning the laser cavity. 12. The sensor of claim 11, wherein the moveable mirror may be adjusted to tune the laser cavity to a particular wavelength. 13. The sensor of claim 12, wherein the wavelength may be adjusted to determine the kind of fluid in the containing structure.