| 摘要 |
PURPOSE:To obtain an optical switch, of which operation is stabilized even in the case where the environment is changed by monitoring the zero-order light, and comparing it with the output of a semiconductor laser, and controlling a light source so as to obtain the minimum artificial diffraction efficiency. CONSTITUTION:Zero-order light, which is not diffracted by a hologram 4, is reflected to a predetermined direction and enters a light receiving element 7. A light receiving element 8 for receiving the light, of which output is proportional to the light going out from the rear part of a DFB laser (a) in the optical fiber Fa direction, is provided. The output of the zero-order light detected by the light receiving element 7 and the output of the laser detected by the light receiving element 8 are compared with each other by a difference amplifier 9, and a result of this comparison is made to feedback to a wavelength converting element DBR so as to obtain the minimum artificial diffraction efficiency. Since the DBR laser (a) and the wavelength converting element DBR are combined to form a light source, diffraction efficiency is stabilized securely even in the case where the environment is hanged or time is passed by feedbacking a result of the output of the zero-order light and the DFB laser (a). |
