Patent ID: 6711185
Filing Date: 2004-03-23
Classification: H01S

Abstract:
A wavelength tunable laser source comprising:a laser medium for producing light; a filter that receives the light and is tunable in wavelength to filter the light; and an optical arrangement in an optical path between the laser medium and the filter, wherein said optical arrangement includes: a first polarization converter for converting a state of polarization of the light received by the first polarization converter in a first way; a second polarization converter for converting a state of polarization of the light received by the second polarization converter in a second way; and a polarization dependent coupling device, between the first polarization converter and the second polarization converter, for coupling out a portion of the light received by the coupling device, and having a coupling ratio that substantially depends on a state of polarization of the light received by the coupling device, wherein the optical arrangement receives, from different sides, beams of the light propagating in different directions, and wherein the polarization dependent coupling device receives beams of the light propagating with different states of polarization in the different directions, such that (a) a first portion of the light returning from the filter is coupled out and (b) a second portion of the light propagating to the filter is coupled out, wherein the first portion is greater than the second portion.