PURPOSE: To reduce oscillation threshold current and operational current by eliminating waveguide scattering and by reducing conductor path loss by forming an active layer stripe by a selective growth method using a mask and by flattening a sidewall thereof in an atomic layer order.

CONSTITUTION: Two stripe masks 2 adjacent to each other in <011> direction are formed on a (100) surface of a semiconductor substrate 1 consisting of n-InP. A buffer layer 3, an active layer 4 formed out of InGaAs or InGaAsP, and a second clad layer 5 consisting of p-InP are formed by an organic metal vapor growth method by using the stripe mask 2 as a selective mask to form an active layer stripe 13 and a double channel 6. After the stripe mask 2 is removed, a first block layer 7, a second block layer 8, a buried layer 9 and a cap layer 10 are formed. A current constriction structure is formed by performing impurity diffusion selectively above the active layer stripe 13.