Abstract: A harmonic generator laser system which features a distributed Bragg reflector (DBR) or distributed feedback (DFB) tunable diode laser coupled to a quasi-phasematched (QPM) waveguide of optically nonlinear material. Tuning of the DBR laser may be achieved either thermally or via current injection, or both, halving the wavelength of a red laser into the visible blue spectral band. Thermal tuning may provide a coarse tuning adjustment, while injected current may provide fine tuning accessible to a user. Separately or in combination with current tuning, a modulation signal may be applied to the DBR laser for achieving an intensity modulated or a pulsed output. In another embodiment, modulation may be achieved by frequency modulation of the laser. A very compact tunable blue laser is formed. In yet another embodiment a double clad fiber amplifier is disposed between the tunable laser and the waveguide.

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 diode laser source including a laser diode whose emitting element or elements is divided into a plurality of concurrently driven laser segments. Beam filling and focusing optics are disposed in front of the segments so that light from the segments in each element converges to a single overlapping spot. The optics include a beam filling lens array collimating the light from the segments and either a single focusing lens or a second lens array focusing the collimated light to corresponding spots. In the case of a multi-element laser diode array, each multi-segment element of the array is individually addressable so as to be driven independently from the other array elements. The segmentation of laser elements improves laser life by reducing thermal gradients and isolating any local failures to a single segment, while the focusing of the segments to overlapping light spots increases the tolerance of the source to local failures.

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 fibre Bragg grating is used to stabilize the intensity and frequency fluctuations of two diode lasers simultaneously. The polarized optical output from the diode lasers is collimated and directed through a beam combiner device which combines the separate beams into a single beam, thus summing the optical power. The combined beam is directed into an optical fibre containing a fibre Bragg grating which reflects a fraction of the light back into each diode laser to cause low-coherence, stable operation of each laser.

Abstract: A fiber laser or amplifier in which the optical fiber gain medium has two or more nonconcentric core regions, each of which is capable of gain or lasing when optically pumped. The fiber may be single clad or double clad, with multiple core regions embedded within a common cladding region or within separate cladding regions. The core regions may be arranged in a linear, closely spaced hexagonal, rectangular matrix or some other configuration and positioned symmetrically or noncentrosymmetrically, centered or off-center within the core region or regions. The spacing between neighboring core regions may be far enough apart to minimize optical interaction between cores for independent light amplifying or laser action or be close enough for phase-locked operation of the multiple cores to occur. The cores may be doped with the same or different active ionic species, of which one or more could be upconverting ions.

Abstract: A semiconductor laser that includes a monolithic submount with a light emitting source aligned along one side thereby defining a radiation path over which the emitted light propagates. The submount includes two notches that flank the light emitting source. A micro-lens is mounted adjacent to the light emitting source by attaching to the submount with either epoxy or solder. Finally, the components of the semiconductor laser have matching coefficients of thermal expansion so that the optical alignment of the light emitting source and the micro-lens is maintained notwithstanding thermal cycling.

Abstract: An optical amplifier semiconductor device which is differentially pumped and a master oscillator power amplifier (MOPA) device employing such an amplifier. The amplifier allows the light propagating therein to diverge along at least part of its length, and may be a flared amplifier having a gain region that increases in width toward its output at a rate that equals or exceeds the divergence of the light. The amplifier is pumped with a current density at its input end which is smaller than the current density used to pump the output end for maintaining coherence of the beam to high power levels. Differential pumping may be both longitudinal and lateral within the amplifier. A single mode preamplifier section may be optically coupled to the input end of the amplifier. The amplifier input may have a width which is the same as or wider than that of the preamplifier output. The preamplifier may have a constant mode width or may be tapered to alter the divergence of the beams provided to the amplifier section.

Abstract: A wavelength-stabilized, 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: An upconversion fiber laser with a double-clad fiber is pumped with a laser-diode-based laser pump source, the inner cladding of the fiber forming a low transmission loss waveguide for the pump light. The central core of the fiber is doped with an active lasing ionic species capable of undergoing upconversion excitation, such as certain rare earth ionic species. The use of a double-clad fiber permits the use of high power, high brightness laser diodes, including those with broad emitting apertures, as well as high power diode laser pumped fiber lasers, as the pump source, thereby achieving higher pump intensities within the upconversion laser fiber and improved upconversion efficiency. Pump brightness can be further increased with multiple pump schemes which use multiple pump wavelengths in different absorption bands, multiple pump wavelengths within the same absorption band, pump light from pairs of cross-polarized sources, and pumping from both ends of the fiber.

Abstract: A cooling device formed in a thermally conductive substrate having a microstructure, such as a plurality of thermally conductive posts spaced apart by dimensions that induce capillary action in a liquid coolant. The posts extend away from the heated region and a space between the posts is supplied with liquid coolant which is contained by a meniscus near the tips of the posts. The coolant vaporizes at the meniscus and absorbs heat but, due to increased pressure in the coolant contained by the meniscus, does not boil within the space between the posts, allowing more liquid coolant contact with the thermally conductive substrate and posts. The vaporized coolant may be discharged into the air or into a chamber adjoining the tips having a lower pressure for removal of additional heat by gaseous expansion. The discharge of gaseous coolant allows the capillary flow of the liquid coolant in the space to be unimpeded, and the flow of liquid coolant may be augmented by a fluid pump.

Abstract: A laser diode package incorporating a first laser diode (or diode laser array) for providing a modulated light output and a second laser diode (or diode laser array) with substantially similar thermal operating characteristics which is modulated with a complementary current signal relative to the modulated current signal driving the first laser diode. The two laser diodes are mounted in close proximity to one another on a temperature controlled heat sink. For diode laser arrays, slots are provided in the heat sink between adjacent array elements. The complementary modulation of corresponding elements in each laser diode ensures that the combined heat generation by each such corresponding pair of elements is constant in time. In the case of digital modulation, the driver logic and current drivers providing the complementary modulation signals may be a modulation controlled switch routing a constant current to one or the other of each corresponding pair of laser elements.

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 cooling device formed in a thermally conductive substrate having at least one microchannel of dimensions that induce capillary action and a surface in thermal contact with a heated region. The microchannel has a longitudinal opening oriented away from the heated region and is supplied with liquid coolant which is contained by a meniscus near the opening. The coolant vaporizes at the meniscus and absorbs heat but, due to increased pressure in the coolant contained by the meniscus, does not boil within the microchannel, allowing more liquid coolant contact with the thermally conductive substrate and walls. The vaporized coolant is discharged into a chamber facing the opening which can be at a lower pressure to remove additional heat by gaseous expansion. The discharge of gaseous coolant allows the capillary flow of the liquid coolant in the microchannels to be unimpeded, and may be augmented by a fluid pump.

Abstract: A phased array of flared amplifiers fed by phase adjusters and a power splitter produces a single high power beam when the flared amplifier sections are aligned and closely spaced. In one embodiment the array is excited by a DBR laser integrated into the same substrate as the flared amplifiers. In another embodiment the array is self-excited and forms a laser between an edge of the substrate common to the power splitter and an edge of the substrate common to the flared amplifier.

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.