| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor laser device which is hardly affected by return light. SOLUTION: Laser light L1 emitted from a semiconductor laser 2 is shaped into a horizontally long beam of light by narrowing a vertical radiant angle via a cylindrical lens 3a, and then transformed into parallel light via a nonspherical lens 3b. The laser light L1 transformed into the parallel light via the nonspherical lens 3b falls slantly to the incident end face 4a of an optical fiber 4 after passing through a nonspherical lens 3c. Part of light falling to the incident end face 4a of the optical fiber 4 is reflected on the end face 4a to become return light L2. The slant incidence of the laser light L1 on the incident end face 4a causes the return light L2 to proceed along a light path separated from that of the laser light L1 and falls to the nonspherical lens 3c, which transforms the return light L2 into the parallel light. A filter 5A is arranged in the light path for the return light L2, and cuts off the return light L2 without cutting off the laser light L1 by means of the filter 5A. COPYRIGHT: (C)2006,JPO&NCIPI
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