In addition, in case of, for example, a two-layer structure of gold/chromium (Au-Cr), there is a method of covering the substrate with a Cr layer with vapor deposition or sputtering, and then applying Au-plating onto the Cr thin film so as to form an Au/Cr metallized pattern. [0114] The semiconductor LD that was used here is a laser whose emitted-light wavelength is 1.3 ??m and in which InGaAsP is