Patent attributes
A tuning layer is disposed spaced by some distance apart from an active layer in a thickness direction, the tuning layer having a transition wavelength shorter than a wavelength of light radiated from the active layer. A diffraction grating layer is disposed between the active layer and tuning layer, a refractive index of the diffraction grating layer being periodically changed along an optical resonator direction. A first electrode supplies the active layer with current. A second electrode supplies the tuning layer with current independently from the current to be supplied to the active layer. A TTG-DFB laser is provided which can maintain a proper coupling coefficient and has characteristics suitable for application to communication light sources.
