| 摘要 |
PURPOSE:To enable execution of an LD drive under an optimum condition with an injection current varied, by a method wherein an automatic resistance control circuit constructed of a functional element and a control circuit is provided for a part of an electrode and a voltage control is executed while an output is monitored. CONSTITUTION:When an injection current ratio is varied by a divided electrode 4 in the case when a wavelength is made variable, a refractive index is changed with a change in the density of injected carriers due to a plasma effect. With the change in the refractive index, a grating pitch shifts equivalently, so as to change an oscillation wavelength. In order to vary this injection current ratio, an impression voltage of a functional element 21, e.g. a diode, is varied by a control circuit 22 while the oscillation wavelength as a light output is monitored. Thereby a resistance value is varied indirectly and the injection current ratio is varied. According to this constitution, the injection current ratio can be varied by varying a resistance ratio indirectly. |
