A laser device using an inorganic electro-luminescent material doped with a rare-earth element is provided. A dielectric layer such as SiO2 is arranged on a silicon substrate. A polycrystalline thin film of Er-doped ZnS or ZnSe is arranged on the dielectric layer. An electrode is formed on the dielectric layer. After a waveguide structure is substantially formed, a reflector is formed at both ends of the waveguide structure to form a laser resonator. An active medium is a polycrystalline material of Er-doped ZnS or ZnSe. When an AC voltage is applied between an electrode attached to the substrate and an electrode attached to an uppermost part, the effect of emitting light at 1550 nm and generating population inversion is used.