| 摘要 |
PURPOSE:To enable wavelength chirp to be controlled and to prevent transmission pulse waveform from being distorted by setting reflection end face phase or diffraction grid phase discontinuity to a specified value of compensating for change of oscillation wavelength as time changes on pulse modulation. CONSTITUTION:A diffraction grid 1 is formed on InP substrate, a phase discontinuity 2 of the grid 1 is formed at the center of resonator, and a non-reflection coating is provided at both end faces 3 and 3' to reduce reflection factor to 3% or less. Then, product kL of a connection coefficient k of light wave by the diffraction grid 1 and the length of resonator is set between 0.8 and 3.0 except closer to 1.3 and the amount of phase shift theta of the discontinuity 2 is set between npi+0.5pi and npi+0.75pi. In this manner, wavelength fluctuation cancels each other, wavelength chirp (oscillation wavelength changes as time passes) is controlled, and transmission pulse waveform distortion is prevented. |
