| 摘要 |
PURPOSE:To reduce relative intensity noise(RIN) and to simplify the structure, by combining optically an intensity modulated laser diode(LD) and an optical fiber. CONSTITUTION:Light output from an LD 21 is conducted into an optical fiber 23 through an optical coupler 22. The input side of the optical fiber 23 is supported by a ferrule 24 while the output side is connected to an optical connector 25. Light is reflected on the surface of an optical part such as a focusing rod lens in the optical coupler 22. A reflection position 27 where light is reflected and the end of the LD 21 to output light are located so that they meet the conditions of the formula below. Supporting that the optical distance (the product of an actual distance and an average refractive index of a light path) between the end of the LD 21 to output light and the position where light is reflected is lR, the period of a modulated signal of the LD is T and the velocity of light (about 3.0X10<8>m/s) is (c), the reflection device should be located to meet the formula lR NXTXC/2 (N=1, 2, 3,...) for the reflected feedback light to enter the LD at the same time when the LD emits light. |
