Anisotropic distributed feedback fiber laser sensor
US6885784B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 2, 2001 |
| Grant date | Apr 26, 2005 |
| Priority date | — |
| Expiry date | Feb 3, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L11/025
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention relates to a DFB fiber laser sensor (1). A measurement quantity makes it possible to induce a linear birefringence between mode pairs of the laser-amplifying fiber (2) and to measure an associated beat frequency (Δν1, Δν2, Δν3). According to the invention, the laser-amplifying fiber (2) has a nonrotationally symmetrical structure, so that it is possible to detect isotropic pressures p, acoustic waves or chemical substances that can be added radially to the laser-amplifying fiber (2). In a second aspect of the invention, an emission wavelength range and parameters (a, b, ΔN) of the laser-amplifying fiber (2) and also a grating period L of the fiber Bragg grating resonator (3) are coordinated with one another such that at least two different spatial modes (LP01, LP11even, LP11odd, LP21even) are propagatable and it is possible to measure beat frequencies (Δν1, Δν2, Δν3) between oscillatory longitudinal laser modes assigned to them. Exemplary embodiments relate to: rotationally asymmetrical fiber types, a choice of special spatial modes (LP11odd, LP21even) and/or multiple fiber Bragg gratings (3) for reducing the beat frequencies (Δν1, Δν2, Δν3) below 100 GHz; and elimina…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.