| 摘要 |
PURPOSE:To split a light beam in an exact ratio by making a light beam emitted from a semiconductor laser incident on a polarizing beam splitter, fetching a light beam whose polarization direction is uniform, and furthermore, making this light beam incident on a half mirror to split it. CONSTITUTION:A polarized light beam splitter 5 allows a light beam polarized in the direction parallel to a joint surface 3a of a semiconductor laser chip 3 to transmit through, and reflects a light beam polarized in the direction vertical to the joint surface 3a, among the incident light beams. The light beam which has transmitted through the beam splitter 5 is made incident on a half mirror 6 which has been provided on an optical bath. This mirror 6 reflects a part of the incident light beams, and allows the remaining light beams to transmit through, and splits the light beams into two light beams in a desired ratio thereby. The light beam which is made incident on the mirror 6 is divided into two pieces of light beams in an exact ratio by the mirror 5, irrespective of the light quantity of the incident light, because the polarized light direction is uniform. Accordingly, for instance, when a photodetector 7 is provided on an optical path of the light beam which has been reflected by the mirror 6, the light beam which has transmitted through the mirror 6 can be monitored exactly by its reflected light. |
