摘要:
An upconversion fiber laser uses a pump source which may be another fiber laser, such as a high power, diode-laser-pumped, fiber laser. The upconversion fiber laser includes an optical fiber whose core region is doped with an active lasing ionic species capable when optically pumped of undergoing upconversion excitation, such as certain rare earth ionic species, and which is embedded in a cladding of the optical fiber. Use of a fiber pump laser can improve coupling of pump light into the optical fiber, thereby achieving higher pump intensities in the core region and improved upconversion efficiency. The upconversion fiber laser's resonant laser cavity is defined by feedback means which can include at least one reflective grating formed in the optical fiber, as well as a reflective end face of the optical fiber. Any portion of the optical fiber that lies outside of the resonant laser cavity, such as any portion beyond the integral reflective grating, may act as an optical power amplifier for the upconverted laser output. The disclosure includes other embodiments in which pump brightness can be further increased with multiple pump sources.
摘要:
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. Single pass or multipass configurations with reflectors could be used, as well as external resonator and segmented, periodically poled waveguide configurations.
摘要:
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.
摘要:
A semiconductor laser that includes at least one grating reflector with a grating period selected to diffract at a nonperpendicular angle within the plane of the laser waveguide. This allows dispersal of laser light, eliminating filamentary multimode operation of broad area lasers. In one embodiment, the grating reflector couples light between a single transverse mode waveguide portion of the optical cavity and a second, broad area, portion that is not collinear with the single mode waveguide. In another embodiment, the cavity favors a ring mode of oscillation. One or more grating reflectors form part of the feedback mechanism which forms a resonant optical cavity with noncollinear portions. Other reflectors in the feedback mechanism include facet reflectors which can be cleaved or ion milled, or semiconductor material refractive index boundaries. Laser embodiments with two or more grating reflectors can be independently tuned to provide a high rate of amplitude modulation. Spatial beam deflection and wavelength tuning are also achieved. A stable unidirectional ring laser is also described. Multiple ring laser cavities can also be coupled together by partially reflecting grating reflectors to form a laser array.
摘要:
Arrangements for efficiently coupling light between a laser diode and a second-harmonic generator which feature external resonant cavities that include a feedback grating fabricated on the second-harmonic generator. The feedback grating reflects light of a first frequency that matches the frequency doubling band of the second-harmonic generator, thereby establishing stable laser oscillation at that first frequency. Preferably, the second-harmonic generator has a periodically-poled waveguide formed in the surface of the nonlinear material body. The laser diode may be butted against the harmonic generator or coupling optics may be positioned between the two. In one arrangement, a polarizer is placed in the resonant cavity, either between an external back reflector and the back facet of the laser diode or between the antireflection coated front facet of the laser diode and the harmonic generator, to provide loss to the TE polarization mode and enhance oscillation in the TM polarization mode. In another arrangement, a half-wave plate is positioned between the antireflection coated front facet of the laser diode and the input end of the harmonic generator to cause TE mode oscillation in the laser diode, while coupling TM polarized light into the harmonic generator. The laser diode may be a monolithic laser diode array with multiple emitters, with the second-harmonic generator having multiple waveguides for receiving and doubling the frequency of light received from a corresponding diode emitter. The diode array may be a multiple wavelength array.
摘要:
Power scaling by multiplexing multiple fiber gain sources with different wavelengths, pulsing or polarization modes of operation is achieved through multiplex combining of the multiple fiber gain sources to provide high power outputs, such as ranging from tens of watts to hundreds of watts, provided on a single mode or multimode fiber.
摘要:
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. Single pass or multipass configurations with reflectors could be used, as well as external resonator and segmented, periodically poled waveguide configurations.
摘要:
A diode laser of the type having an array of laser emitters in a Talbot cavity in which edge reflectors are added to enhance feedback to edgemost emitters. In one embodiment, a transparent slab with reflectively coated sides is present between the phase plane of the emitted light and the Talbot cavity reflector. The phase plne is defined by a lenticular array placed a focal length in front of the laser emitters. In another embodiment, the Talbot cavity reflector has an increased reflectivity toward its edges. In all embodiments the Talbot cavity reflector is preferably spaced a distance na.sup.2 /.lambda. from the phase plane, where n is a positive integer, a is separation between adjacent emitters and .lambda. is the wavelength of emitted light. An integrated embodiment has the array and cavity reflectors defined ina single semiconductor body divided into active and ransparent region. Side mirrors are etched into the semiconductor body. The laser array may also be extended to two dimensions with individual lasers or laser bars fiber coupled to a lens surface, with an edge reflector and Talbot cavity reflector coated on an otherwise transparent slab.
摘要:
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.
摘要:
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.