Abstract: A semiconductor laser having a light amplifying diode heterostructure with a flared gain region in an external resonant cavity. The flared gain region has a narrow aperture end which may be coupled to a single mode waveguide and a wide output end. A light emitting surface of the heterostructure proximate to the wide end of the flared gain region is partially reflective and combines with an external reflector to form a resonant cavity that is effectively unstable. The intracavity light-emitting surface proximate to the narrow aperture end is antireflection coated. The external reflector may be a planar mirror or a grating reflector. A lens or an optical fiber may couple the aperture end of the flared gain region to the external reflector. Frequency-selective feedback is provided by orienting the grating reflector or providing a prism in the cavity in front of the external planar mirror. Other filtering elements may also be placed in the external cavity.

Abstract: A monolithic multi-wavelength laser diode array having a composite active region of at least two dissimilar quantum well layers that are partially mixed in at least one of their constituent atomic species in at least one area of the active region. Different areas of the active region are characterized by different emission wavelengths determined by the degree of intermixing. An impurity free interdiffusion, such as vacancy enhanced interdiffusion, is used to provide the intermixing. Each area may have one or more waveguides and distributed Bragg reflector gratings tuned to the emission wavelength of the corresponding area of the active region. Each area or waveguide may also be separately pumped with an individually addressable current injection electrode. The laser output may be coupled into a ferroelectric frequency doubler integrally formed on the array substrate.

Abstract: A coherent light source, such as a laser oscillator and a monolithic MOPA device, and a broad area light amplifying device, all characterized by having a leaky waveguide beam expander coupled thereto for expanding a single mode beam into a wide light beam in a coherent manner. The beam expander comprises an elongated antiguide core of a first refractive index and a radiated-wave receiving region of a higher refractive index to receive lightwaves laterally radiated from the antiguide core. This beam expander can be located at an output end of a single mode laser oscillator to receive and expand the beam, at an input end of a broad area optical power amplifier to allow the amplifier to accept a narrow input beam, or between the laser oscillator and power amplifier in a MOPA device. The beam expander elements can also be located partially or entirely within the resonant optical cavity of a laser oscillator.

Abstract: A semiconductor laser includes a grating that is disposed at an angle to cavity reflectors to coherently diffract a beam of light along a path that is at least partially laterally directed within the cavity. The grating period and orientation are selected such that a specified wavelength of the light beam propagating along the path will resonate for light that impinges upon the end reflectors at normal incidence. By keeping the angle of incidence of the light beam upon the grating greater than about 45 degrees, reflectivity of the grating is maximized and the required grating period is larger thereby simplifying the fabrication of the grating.

Abstract: A compact semiconductor laser light source providing short wavelength (ultraviolet, blue or green) coherent light by means of frequency doubling of red or infrared light from a high power diode heterostructure. The high power diode heterostructure is a MOPA device having a single mode laser oscillator followed by a multimode, preferably flared, optical power amplifier. A tunable configuration having an external rear reflector grating could also be used. A lens could be integrated with the MOPA to laterally collimate the light before it is emitted. Straight or curved, surface emitting gratings could also be incorporated. An astigmatism-correcting lens system having at least one cylindrical lens surface is disposed in the path of the output from the MOPA to provide a beam with substantially equal lateral and transverse beam width dimensions and beam divergence angles. A nonlinear optical crystal or waveguide is placed in the path of the astigmatism-free symmetrized beam to double the frequency of the light.

Abstract: An optical amplifier with at least one high reflectivity facet oriented at a nonperpendicular angle to the amplifier's waveguide to couple light vertically through a top or bottom surface of the amplifier. Angled facets could be at just one end of the waveguide or at both ends of the waveguide. In the latter case, the facets can be approximately parallel to or perpendicular to each other for respective coupling to opposite or same sides of the amplifier. Multiple amplifiers can be formed end-to-and with v-grooves defining the angled facets or can be formed side-by-side with parallel waveguides. Waveguides can also branch to form a 1:2, 1:4 or 2:2 optical signal multiplier or optical switch depending on whether just one or all of the waveguide branches are electrically pumped. Fibers are coupled to the amplifier receiving and emitting surfaces. Angling the fiber end with respect to the surface prevents reflections from feeding back into the amplifier waveguide.

Abstract: An optical crossbar switch matrix for use in switching optical signals from a first set of optical fibers to a second set of optical fibers, in any order, which is characterized by having a matrix of rows and columns of diffraction gratings formed in a semiconductor heterostructure. Each grating is independently biased with either a forward or reverse bias voltage to switch the grating between a reflective state and a transmissive state. The gratings are oriented at an angle relative to the rows and columns so that when the Bragg condition for the light received from an optical film is met, a portion of the light is diffracted from the row in which it is propagating into a column toward another optical fiber. The heterostructure may include optical amplifiers to restore the optical signal to its original power level. Beam expanding, collimating and focussing optics may also be integrated into the heterostructure.