| 摘要 |
PURPOSE:To make a precise optical axis matching unnecessary and to simplify an adjustment of a mutual position to other optical element such as a light source, etc. by laminating two kinds of semiconductors and forming a titled lens. CONSTITUTION:A semiconductor thin film lens 10 is formed by laminating alternately a GaAs layer 12 and a Ga0.7Al0.3As layer 13 on a GaAs substrate 11. A forbidden band width, a refractive index and a thickness EgA, nA and dA, and EgB, nB and dB of the layers 12, 13 satisfy a condition of EgA<EgB, nA>nB, and the thicknesses dA, dB are made sufficiently thinner than a wavelength corresponding to the forbidden band width. Impurities of a different quantity are mixed in each semiconductor layer so that the refractive index becomes high in the center part in the direction (z), and becomes low in the substrate and the upper layer side. A light of energy being below a forbidden band width Eg of the thin film lens 10, which advances in the direction (y) is focused at some position so as to draw a sine curve in the direction (z), and an asymmetrical beam emitted from a semiconductor laser 15 can be fetched as a circular symmetrical beam 16. |
