Patent ID: 7391942
Filing Date: 2008-06-24
Classification: G01J,G01N

Abstract:
1. A method for detecting one or more compounds in a test medium, comprising: providing an optical sensor comprising a long period grating; providing an optical waveguide loop optically connected to said optical sensor; using fiber loop ring-down spectroscopy to measure and compare at least one optical property of the sensor exposed to the test medium with at least one corresponding optical property of the sensor in absence of the test medium, a result of said comparison being indicative of detection of the one or more compounds; wherein said fiber loop-down spectroscopy comprises: launching in the optical waveguide loop an intensity-modulated light at a reference phase; detecting a phase of said light along the optical waveguide loop; and comparing the detected phase of said light along the loop with the reference phase; wherein comparing the detected phase and the reference phase provides information about said at least one optical property of the optical sensor.