Semiconductor laser

Abstract

The invention provides a semiconductor laser including a p-type semiconductor layer, an active layer, and an n-type semiconductor layer sequentially laminated on a p-type semiconductor substrate; and a diffraction grating in the n-type semiconductor layer along the direction of an optical waveguide. The reflectance of light on two facing laser end surfaces is asymmetric; the length L of the active layer in the optical waveguide direction is 130 mum or shorter; the diffraction grating material has a photoluminescence wavelength of 1,200 nm or longer; and kappa L, which is the product of the length L and the coupling coefficient kappa of the diffraction grating, is at least 1.5 and smaller than 3.0.

Description

technical field [0001] The present invention relates to a semiconductor optical element capable of ensuring good initial characteristics and long-term reliability and improving high-speed response and single mode performance. Background technique [0002] Semiconductor lasers used for optical communications that perform direct modulation must achieve high-speed response of about 10 Gbps even at high temperatures. Therefore, the optimization of the quantum well structure of the active layer, the high reflection achieved by coating the light exit end surface, the reduction of parasitic capacitance, the shortening of the length L of the optical waveguide direction of the active layer, and the increase of distributed feedback type or distribution A material having an Al element such as AlGaInAs is used for the coupling constant κ of the diffraction grating and the active layer in the reflective semiconductor laser. [0003] Patent Document 1: Japanese Patent Laid-Open No. 2003-...

AI Technical Summary

Problems solved by technology

Therefore, in an AR / HR type semiconductor laser whose light reflectance is asymmetrical at the two facing laser end faces, there is a problem that the single-mode characteristic is degraded due to an excessively large κ L.

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