| 摘要 |
PURPOSE:To decrease the generation of noise by the return light to a laser by confining the reflectivity of the light incident surface of a prism to <=25%. CONSTITUTION:The light generated from a semiconductor laser diode LD is reflected by the light incident surface 2a of the prism 2 and an optical disk 5 having bit information is irradiated with this light via a lens system 4. The reflected light modulated according to this information is introduced from the light incident surface 2a of the prism 2 into the prism 2 and is introduced to plural sets of photodiodes PDs on an optical IC substrate 1. The reflectivity of the light incident surface 2a of the prism 2 as an optical coupler is confined to <=25%. The noise is decreased in this way, i.e. the S/N is improved. |
