| 摘要 |
PURPOSE:To make a light intensity distribution flat in a direction of a resonator when the resonator is made larger in length by a method wherein at least an active layer is provided through the whole length of the laser resonator in a light travelling direction and a distributed feedback diffraction grating formed along the active layer is contained only in a central part of the resonator. CONSTITUTION:A part of a diffraction grating 3 near an end face of a distributed-feedback semiconductor laser is removed or the diffraction grating 3 is provided only to a central part of the semiconductor laser, and the semiconductor laser is so structured that an active layer is provided through the whole length of a resonator. Thereby, a light intensity distribution of a laser of this design conforms to that of a laser structure that two types of lasers, a Fabry-Pelot laser and a distributed-feedback laser, are combined and is uniform as shown in in a figure (B), and the laser of this design is small in a spectral line width and operates stably at a high output without causing a multi-wavelength oscillation. And, as the laser is formed to be the same in structure toward a light travelling direction, when an optical output increases, the laser is free from such problems as a multi-wavelength oscillation and a leap in wavelength which used to occur in a conventional type of laser that a laser region provided with an active layer and a waveguide path provided with no active layer are integrated, so that a stable oscillation of laser rays with a single wavelength and a small spectral line width can be realized. |
