| 摘要 |
PURPOSE:To prevent the breakdown of an element and chirping due to a current surge by a method wherein a semiconductor laser having an active layer constructed in a superlattice is driven by a DC-constant current, the optical confinement of a laser resonator is controlled by using the field dependence of the refractive index of the superlattice, and an optical output is modulated by the modulation of a voltage. CONSTITUTION:When a current is injected from a central electrode 8 toward a common electrode 6, this semiconductor laser makes oscillation in a gain waveguide type. When a voltage is impressed between electrodes 7 and 6, the refractive index of an active layer 3 of superlattice structure lowers in accordance with the distribution of field intensity. Therefore, there occurs a refractive index difference between the central portion (wherein the refractive index is large) of the active layer 3 positioned at a place just below the electrode 8 to which an electric field does not extend or extends very weakly, and the outside portion (wherein said index is small) thereof, and it becomes possible to confine a light in a central narrow region by a refractive index waveguide resistance. Thus, the oscillation is made in a lateral fundamental mode. In this way, it becomes possible to modulate the intensity of an optical output only by modulating a voltage impressed on the electrode 7, without changing an amount of current injected from the electrode 8. |
