| 摘要 |
PURPOSE:To obtain an excellent signal to noise intensity ratio, by forming an uneven state in the light amplifying direction in at least one of the phase or period of the diffraction grating of a light amplifier, which has a distribution feedback structure or a distribution reflecting-mirror structure comprising a laminated structure including semiconductor active layer for light amplification and the diffraction grating. CONSTITUTION:A light amplifier element is composed of the following parts: a buffer layer 2, which is epitaxially grown on a semiconductor substrate 1; a semiconductor active layer 3; a guide layer 4 including a diffraction grating 41 and a 1/4 wavelength phase shifting region 42; a clad layer 5; an electrode forming layer 6; an n-side electrode 7; a p-side electrode 8; and a reflection preventing film 9. A current is injected from the p-side electrode 8 into the active layer 3, and a light signal, which is inputted to one end surface of the element, is amplified and taken out of the opposite end surface. Since the 1/4 wavelength phase shift region 42 is provided at the center of the element, the element is operated as the light amplifier element, which has a high optical gain on the effective Bragg wavelength determined by the average period of the diffraction grating. |
