Abstract: A DBR grating may be created in the cladding of a wafer by defining a non-gain window area, advantageously at the end of the wafer. The non-gain area may be defined either by removing all layers above the cladding layer at the window portion or, preferably, by halting the MOCVD process once the cladding layer has been created and by selectively removing from a portion of the cladding layer a protective coating, advantageously of SiO2, Si3N4, or a metal, to define the window area. A photo resist is applied, and the wafer is exposed to interfering laser beams to create a grating pattern in the photoresist, conveniently without the need for any particular effort to confine either the photoresist or the interfering beams solely to the window area. The photoresist is developed and an etchant used to transfer the pattern into the cladding layer.

Abstract: A wafer supporting a semiconductor structure having a material gain function that would preferentially support an Fabry-Perot laser mode at an unwanted wavelength &lgr;2 is provided with a second-order dielectric grating located sufficiently remotely from the high intensity optical field of the quantum well and the waveguide layers to receive just enough transverse mode energy to provide feedback to reduce the gain at &lgr;2 and support oscillation at a desired wavelength &lgr;1. More particularly, by locating the grating in an unpumped area not requiring epitaxial overgrowth and so as to provide a gain discrimination factor &Dgr;g≈0.1 cm−1 at the desired wavelength &lgr;1, the fraction of power lost to transverse mode radiation can be held to about 1% which is sufficient to provide stabilizing feedback without sapping too much energy from the longitudinal beam.

Abstract: A wafer supporting a semiconductor structure having a material gain function that would preferentially support an Fabry-Perot laser mode at an unwanted wavelength &lgr;2 is provided with a second-order dielectric grating located sufficiently remotely from the high intensity optical field of the quantum well and the waveguide layers to receive just enough transverse mode energy to provide feedback to reduce the gain at &lgr;2 and support oscillation at a desired wavelength &lgr;1. More particularly, by locating the grating in an unpumped area not requiring epitaxial overgrowth and so as to provide a gain discrimination factor &lgr;g≈0.1 cm−1 at the desired wavelength &lgr;1, the fraction of power lost to transverse mode radiation can be held to about 1% which is sufficient to provide stabilizing feedback without sapping too much energy from the longitudinal beam.