Abstract: The invention is a semiconductor optical device and method of fabrication where the device includes an active region with an active layer having a first index of refraction, and a blocking region having a second, lower index of refraction. A semiconductor layer having an index of refraction higher than the blocking region formed over both the active and blocking regions so that the layer is in closer proximity to the active layer in areas not covered by the blocking region so as to decrease the difference between the effective index of refraction in the active region and the effective refractive index of the blocking region. Such devices are particularly useful for pumping optical amplifiers since greater power can be achieved while maintaining single mode emission.

Abstract: The invention is a semiconductor optical device and method of fabrication where the device includes an active region with an active layer having a first index of refraction, and a blocking region having a second, lower index of refraction. A semiconductor layer having an index of refraction higher than the blocking region is formed over both the active and blocking regions so that the semiconductor layer is in closer proximity to the active layer in areas not covered by the blocking region so as to decrease the difference between the effective index of refraction in the active region and the effective refractive index of the blocking region. Such devices are particularly useful for pumping optical amplifiers since greater power can be achieved while maintaining single mode emission.

Abstract: The present invention is directed to a large area single-mode (LASM) laser system that provides a laser having a wider gain region and thus a higher power output without introducing the second transverse mode into the optical signal. The laser system of the present invention also reduces the laser junction temperature, thereby improving the reliability of the laser and of laser systems constructed therefrom. The present invention also provides a stabilized spectrum in an optical signal by providing a means for feeding back from an external fiber grating to the laser only a single mode and a selective spectrum of an optical signal generated by the laser.

Abstract: The invention is an optical apparatus and method of fabrication wherein an optical device such as a semiconductor laser includes a grating and a waveguide optically coupled to the grating. At least a portion of the waveguide coupled to the grating has a width which varies along the length of the waveguide in such a manner as to broaden the spectral line width of light output from the device. The width can be varied according to linear, sinusoidal or saw-tooth functions. A broadened line width permits pumping of a Raman amplifier at a high power without inducing any significant Brillouin Scattering.

Abstract: An optical laser module exhibits stabilized output power over a range of input bias current and temperatures by utilizing an external Bragg grating with an essentially flat response over the grating bandwidth. The flat response is provided by using a combination of separate external gratings, the gratings exhibit different center wavelengths, with a center wavelength separation of 0.5 nm considered to be optimal.

Abstract: A distributed feedback (DFB) laser is made with a spatially graded optical coupling (.kappa.) between its diffraction grating and its active layer by means of selective area epitaxial growth of the epitaxial layer from which the grating is formed. More specifically, the epitaxial layer is formed on a major surface of a semiconductor substrate on which a mask, such as a silicon dioxide mask, has been formed. The mask has a pair of segments spaced apart by a fixed distance, the segments having spatially variable widths. Advantageously the epitaxial layer has a refractive index that is different from that of the substrate at the operating wavelength of the laser. The epitaxial layer is then etched into stripes. In this way the heights of the resulting grating stripes will be spatially variable, and so will the coupling .kappa. between the grating and the active layer. In this way, the properties of the optical output of the laswer can be adjusted.