| 摘要 |
PURPOSE:To prevent a tracking error by primary-diffracted return light by forming a thin film having a roughened surface on the light receiving part of the primary-diffracted return light at the end face on the exit side. CONSTITUTION:The thin film 11 having the roughened surface is formed in the prescribed region lower than a light emitting part 10a of the semiconductor laser device 10. The film 11 is so formed as to cover the part where the primary-diffracted return light is received. The film is generally so formed as to cover the part lower than 50mum below the light emitting part 10a. The material of the thin film is not particularly limited and the thin film is formable out of optical thin films of dielectric substances, such as Al2O3, SiO2, MgO, MgF2 and TiO2. The same material as the material of a reflectivity adjusting layer is preferable and the Al2O3 is more preferable in the case of formation of the thin film having the roughened surface in the stage for forming the reflectivity adjusting layer to be formed on the exit side end face of the semiconductor laser. The primary-diffracted return light returned from the end face of the semiconductor laser element is irregularly reflected by the roughened thin film to lower the reflectivity. The tracking error, etc., by the primary- diffracted return light are thereby prevented. |
