Abstract: An animal repellant system which includes triggering means for detecting the presence of animals within a particular area and generating signals indicative thereof. The animal repellant system includes a controller operable to receive the signals generated by the triggering means and to issue command signals responsive thereto, and deterrent means for effectuating a repellant component of the animal repellant system in response to the command signals issued by the controller, thereby dissuading the animals from entering the particular area.

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.