| 摘要 |
PURPOSE:To obtain a stable optical characteristic by constructing a semiconductor laser so that the light beam is emitted from a substrate for constituting the semiconductor laser, or the surface of a thin film which has been formed on the substrate. CONSTITUTION:As for semiconductor laser 11, what is called a surface light emission laser is used, and constituted so that a part of thin films 22, 23 which are formed on a substrate 25 goes to an active area 21, a light beam 24 seems to be emitted from a minute surface on the substrate. In this case, the resonance length is L, and very short as about several mum. Accordingly, an oscillatable vertical mode goes to one piece and the oscillation wavelength is also determined to one, and even if a temperature change is large, a wavelength variation due to a skip of a mode does not occur. In such a way, an optical head free from the generation of variation of focal distance and an aberration due to wavelength variation of the light source can be constituted. |
