| 摘要 |
PURPOSE:To stably suppress reflected return light without using any expensive optical component nor lowering output light power by providing an optical fiber connection part which has a gap between a semiconductor laser and the output end of a big-tail optical fiber and controlling the reflective index of the connection part and the length of the optical fiber. CONSTITUTION:A reflection part 6 is provided between the output terminal 4 of the big-tail optical fiber 3 and a laser 2 and further at another position by utilizing the gap of the optical end surface. Therefore, the reflection part is provided at the two positions of the optical fiber connection part 6 having the gap and an optical connector 4 at the big-tail output terminal. Here, the reflection factor of the optical fiber connection part 6 which is provided newly is denoted Rc, the reflection factor of the optical connector 4 at the big-tail output terminal is denoted as Rp, and control is performed with temperature so that Rc=Rp. Consequently, the reflected return light from an optical fiber discontinuous part to the laser 2 is reduced almost to zero. Consequently, no inexpensive optical isolator is used, a decrease in light output power is suppressed, and the reflected return light to the semiconductor laser 2 is suppressed stably by a relatively simple method. |
