| 摘要 |
PURPOSE:To reduce the absorption of laser light at an end plane by coating with a small reflection factor protection film on the front end plane of a resonator and with a great reflection factor protection film in the rear end plane of the resonator. CONSTITUTION:On a substrate formed with a ridge wherein the width is made narrower only near the front end plane F of a resonator, each layer including an active layer is formed and on the front end plane F of the resonator, a protection film of reflection factor less than 32% is coated and on the rear end plane R of the resonator, a protection film of reflection factor more than 32% is coated. For example, a mesa is formed on the (100) plane of the p-type GaAs substrate 1 in the direction <011>, an n-type GaAs current constriction layer 2 is grown and two parallel ridges 2a, 2b are formed. The width of the ridges 2a, 2b is made 10mum within 15mum from the front end plane F and 50mum in the region except the above region. The first-the fourth layers 3-5 are formed, a wafer is cleft, an Al2O3 film 1/4 wavelength thick is coated on the front end plane F and the Al2O3 film 1/4 wavelength thick and an Si film 1/4 wavelength thick are alternately coated with four layers on the rear end plane R.
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