High-resolution fiber laser sensor

US7251023B2 · kind B2 · utility

Assignee

• Vetco Gray Controls Limited · GB

Inventors

• Klaus Bohnert · Oberrohrdorf, CH
• Karim Haroud · Yverdon-les-Bains, CH
• Andreas Frank · Sindelfingen, DE
• Hubert Brandle · Oberengstringen, CH

Key dates

• Filing date: Apr 29, 2003
• Grant date: Jul 31, 2007
• Expiry date: Apr 29, 2023

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/1053
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A high-resolution fiber laser sensor for measuring a quantity to be measured M has a pumping light source, a fiber laser and a detection/evaluating unit. The fiber laser has: a birefringent first end reflector, a second end reflector, a laser-amplifying fiber, a sensor fiber and a mode coupling. The laser-amplifying fiber, the sensor fiber and the mode coupling are arranged between the end reflectors. In the fiber laser, light is capable of propagating in two optical states which are orthogonal to one another due to their polarization and/or their transversal space structure. The orthogonal optical states can be coupled to one another by the mode coupling. In the fiber laser, a number of longitudinal modes are capable of oscillating in each of the two optical states. In the sensor fiber a change in the birefringence for the two orthogonal optical states can be achieved by interaction of the quantity to be measured with the sensor fiber.