Patent ID: 7936509
Filing Date: 2011-05-03
Classification: H01S

Abstract:
1. A wavelength locker, comprising: a birefringent plate separating light emitted from a light source into two beams of light which are approximately in parallel to each other; a first light receiving element directly receiving one of the two beams of light separated by the birefringent plate; a polarizing element and a filter element through which other one of the two beams of light separated by the birefringent plate passes; and a second light receiving element receiving the other one of the two beams of light which has passed through the filter element, wherein the first light receiving element and the second light receiving element are arranged parallel to each other, and wherein the polarizing element changes a polarization direction of light reflected by the filter element and incident on the polarizing element such that the reflected light does not return to the light source after passing through the birefringent plate, and emits a resultant light, and wherein the other one of the two beams of light emitted from the birefringent plate has a same axis that the light emitted from the light source to the birefringent plate has, and the reflected light entering from the polarization element to the birefringent plate has the same axis that the light emitted from the light source to the birefringent plate has, and the reflected light entered in the birefringent plate is emitted from the birefringent plate as a light having an axis parallel to the light emitted from the light source without being separated in the birefringent plate.