| 摘要 |
PURPOSE: To enable wavelength to be varied over a wide range and make this semiconductor laser module simple and economical by making a composite resonator by adding an external resonator to a Fabry-Perot type semiconductor laser diode module. CONSTITUTION: A composite resonator is made, being provided with an external resonator using a loop mirror consisting of a fiber type four-terminal wave branch (fiber coupler) 12 as a third resonator mirror. Furthermore, wavelength selectability is given to the reflection of the loop mirror by providing a film stack type of transmitting filter 17 which lies in a narrow band area and whose transmissive wavelength is variable, in the loop 17. Moreover, the branching- coupling ratio of the fiber coupler 12 is selected so that the reflectance from the loop mirror to LD may be more than or roughly the same as the reflectance of the LD output end face. Hereby, the return light functions strongly as a light synchronized with injection, and the spectrum of oscillation is drawn into the resonance spectrum of an external resonator being a second resonator, and it continues the oscillation which show this spectrum stably. |
