PURPOSE: To enable direct control of oscillating state in the laser by varying a voltage applied to the laser element.
CONSTITUTION: Only the center of the semiconductor layers 2∼5 grown epitaxially are retained in stripe state, and are mesa etched, and thereafter p type Ga 1-z Al z As buried layer 6 is epitaxially grown on a crystalline substrate 1 at the part removed by etching. An n type GaAs buried layer 7 is epitaxially grown on the layer 6, and is aligned with a cap layer 5. Thereafter, source electrode S, is formed under the substrate 1, and a drain electrode D is formed on the layer 5. A gate electrode G is formed on an n type GaAs buried layer 7 in predetermined interval with both ends of the drain electrode D. With the above steps, the semiconductor laser can be constructed. When the gate applied voltage is increased higher than the drain voltage, the laser light can be stopped in oscillation.