| 摘要 |
PURPOSE:To increase productivity and improve reliability of an optical amplifier in a semiconductor laser device and fiber type optical amplifier using such semiconductor laser device as the exciting light beam source by preventing deterioration of the semiconductor laser element resulting from entry of the light beam, to the semiconductor laser element, having the wavelength longer than that of the light beam oscillated by a semiconductor laser element forming a semiconductor laser device and by making unnecessary an optical isolator used for the optical amplifier. CONSTITUTION:An optical filter 2, having low reflectivity for the oscillated light beam lambdap and high reflectivity for the light beam in the wavelength lambdas longer than that of the oscillated light beam, is provided at the end surface, from which the oscillated light beam is emitted, of semiconductor laser element 1 forming a semiconductor laser device. This semiconductor laser device is used as the exciting light beam source of the fiber type optical amplifier. |
