| 摘要 |
PURPOSE:To make an oscillation wavelength variable by mutually adjusting a refractive index of a region by a method wherein a light-emitting region and a waveguide region are integrated and a filter region equipped with a diffraction grating having a filtering function is installed in one part of the waveguide region or one part extended from the region. CONSTITUTION:A laser resonator is composed of a light-emitting region A, a non-light- emitting region (a waveguide region B and a filter region C) and a pair of reflection end faces 12, 12'; there are a number of resonance modes in accordance with a resonator length L which is an effective device length experienced when the light is propagated essentially. A wavelength width depends on a coupling coefficient and a length of a diffraction grating, on a phase shift amount, on a phase shift position and the like; it is possible to pass only one resonance wavelength lambda0 selectively. If a cycle of the diffraction grating 3 is selected, only a wavelength of a resonance wavelength lambda0 is confined strongly inside a resonator; as a result, it is possible to obtain an oscillation at a single wavelength of the resonance wavelength lambda0. By using a semiconductor laser it is possible to satisfy a requirement to operate at a single wavelength and to lengthen the resonator length; it is possible to realize a narrow oscillation line width by the long resonator length. |
