Abstract: One embodiment of the invention includes a method for forming an optical fiber. The method comprises providing a preform having a core material and a glass cladding material surrounding the core material. The method also comprises drawing the preform at a temperature that is greater than a melting temperature of the core material to form a drawn fiber. The method further comprises cooling the drawn fiber to form the optical fiber having a crystalline fiber core and a cladding that surrounds the crystalline fiber core and extends axially along a length of the crystalline fiber core.

Abstract: A method is provided for forming an optical fiber amplifier. The method comprises providing a composite preform having a gain material core that includes one or more acoustic velocity varying dopants to provide a longitudinally varying acoustic velocity profile along the gain material core to suppress Stimulated Brillouin Scattering (SBS) effects by raising the SBS threshold and drawing the composite preform to form the optical fiber amplifier.

Abstract: A method is provided for forming an optical fiber amplifier. The method comprises providing a composite preform having a gain material core that includes one or more acoustic velocity varying dopants to provide a longitudinally varying acoustic velocity profile along the gain material core to suppress Stimulated Brillouin Scattering (SBS) effects by raising the SBS threshold and drawing the composite preform to form the optical fiber amplifier.

Abstract: A system and method for combining plural low power light beams into a coherent high power light beam by means of a diffractive optical element operating as both a beam combiner and beam sampler. An oscillation source transmits a master signal that is split into plural beams propagating at a common wavelength. Each beam is phase locked by a corresponding phase modulator according to a phase correction signal. The beams are directed through a fiber array to the diffractive optical element to allow efficient coherent combination of the beams at a desired diffraction order. The diffractive optical element includes a periodic sampling grating for diffracting a low power sample beam representative of the combined beam. A phase detection stage detects phases of constituent beams in the sample beam from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: A hybrid beam combining system or method combines a plurality of coherent and incoherent light beams into a composite high power diffraction limited beam. N oscillators each transmit light at one of N different wavelengths and each wavelength is split into M constituent beams. M beams in each of N groups are phase locked by a phase modulator using phase correction signals. The phase locked beams are amplified and coupled into an M×N fiber array. Beams emerging from the array are collimated and incident on a diffractive optical element operating as a beam combiner combining the M outputs at each N wavelength into a single beam. The N single beams are incident and spectrally combined on a grating which outputs a composite beam at a nominal 100% fill factor. A low power sample beam, taken from the N beams emerging from the diffractive optical element, is measured for phase deviations from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: A hybrid beam combining system or method combines a plurality of coherent and incoherent light beams into a composite high power diffraction limited beam. N oscillators each transmit light at one of N different wavelengths and each wavelength is split into M constituent beams. M beams in each of N groups are phase locked by a phase modulator using phase correction signals. The phase locked beams are amplified and coupled into an M×N fiber array. Beams emerging from the array are collimated and incident on a diffractive optical element operating as a beam combiner combining the M outputs at each N wavelength into a single beam. The N single beams are incident and spectrally combined on a grating which outputs a composite beam at a nominal 100% fill factor. A low power sample beam, taken from the N beams emerging from the diffractive optical element, is measured for phase deviations from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: A system or method coherently combines a large number of light beams at a single wavelength in multiple stages to form a high-power diffraction limited output beam. A two-stage system, or method based thereon, includes a master oscillator transmitting a light beam to a first phase modulation stage, which splits the beam into N beams and locks beam phases using phase correction signals from a first feedback loop. A second phase modulation stage splits each N beam into M beams and locks the phases of M beams in each N group using phase correction signals from a second feedback loop. A two-dimensional fiber array directs M×N beams to a first diffractive optical element combining the beams into N coherent beams of M beams each, and phase correction signals for the second stage are derived from a sample extracted from the N coherent beams.

Abstract: A system and method for combining plural low power light beams into a coherent high power light beam by means of a diffractive optical element operating as both a beam combiner and beam sampler. An oscillation source transmits a master signal that is split into plural beams propagating at a common wavelength. Each beam is phase locked by a corresponding phase modulator according to a phase correction signal. The beams are directed through a fiber array to the diffractive optical element to allow efficient coherent combination of the beams at a desired diffraction order. The diffractive optical element includes a periodic sampling grating for diffracting a low power sample beam representative of the combined beam. A phase detection stage detects phases of constituent beams in the sample beam from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: A system or method coherently combines a large number of light beams at a single wavelength in multiple stages to form a high-power diffraction limited output beam. A two-stage system, or method based thereon, includes a master oscillator transmitting a light beam to a first phase modulation stage, which splits the beam into N beams and locks beam phases using phase correction signals from a first feedback loop. A second phase modulation stage splits each N beam into M beams and locks the phases of M beams in each N group using phase correction signals from a second feedback loop. A two-dimensional fiber array directs M×N beams to a first diffractive optical element combining the beams into N coherent beams of M beams each, and phase correction signals for the second stage are derived from a sample extracted from the N coherent beams.

Abstract: A system and method for combining plural low power light beams into a coherent high power light beam. Optical amplifiers transmit a plurality of light beams propagating at a common wavelength through an array of optical fiber emitters. Each constituent beam is emitted from the array at a different propagation angle, collimated, and incident on a diffractive optical element operating as a beam combiner such that incident beams when properly phased and located are combined into a coherent beam at a desired diffraction order. A beam splitter or a periodic sampling grating on the diffractive optical element directs a low power sample beam to a spatial filter passing resonant mode output back to the optical amplifiers in a ring laser configuration thereby passively synchronizing phases of the constituent beams to maximize combination efficiency of the coherent beam.

Abstract: A pulsed coherent fiber array laser system that includes a beam generating sub-system that provides a signal pulse beam having pulses of the desired duration that is split into several fiber channels. Optical leakage between the pulses in each split beam is measured and locked to a reference beam by a phase sensing circuit and phase adjusters so that the phase of each fiber pulsed beam is aligned with the phase of the reference beam. A pulse clipper or filter is employed to remove the pulses in the fiber beams so that they do not saturate the phase sensing circuit. The beam generating sub-system can employ any suitable combination of devices to generate the signal beam and the reference beam, including continuous wave master oscillators, amplitude modulators, frequency shifters, injection seed oscillators, Q-switched lasers, reference oscillators, frequency lockers, wavelength division multiplexers, time gated switches, etc.

Abstract: Encircled far field energy is substantially increased by modifying the near field energy distribution of radiation from each fiber in an emitting array. Each beamlet output from a fiber is modified to have a generally uniform cross-sectional energy distribution, using a pair of aspheric optical elements selected for that purpose. The optical elements may be refractive or reflective. The modified beamlets combine to form a composite output beam with a generally uniform energy distribution. Preferably, the composite beam is subject to an array-wide inverse transformation to a near-Gaussian distribution, further enhancing the encircled far field energy and providing a more efficient high power laser source. Further gains in efficiency are achieved by selecting a fiber bundle pattern, lens array pattern and lens shape that together result in a high fill factor.

Abstract: An array of cylindrical end-caps with separate or integral lenses is stacked with its members in close contact, forming inter-cylinder gaps between every subset of three adjacent cylindrical lenses. Conductive fibers are disposed in the inter-cylinder gaps. Heat that would otherwise accumulate in the array is removed through the conductive fibers and transmitted to an external heat sink.

Abstract: A laser array architecture scalable to very high powers by closely stacking fiber amplifiers, but in which the output wavelength is selectable to be in the visible or ultraviolet region, without being restricted by the wavelengths usually inherent in the choice of fiber materials. A pump signal at a fundamental frequency is amplified in the fiber amplifier array and input to an array of nonlinear crystals that function as harmonic generators, producing an output array at a desired harmonic of the fundamental frequency. A phase detection and correction system maintains the array of outputs in phase coherency, resulting in a high power output with high beam quality, at the desired frequency. The array of nonlinear crystals may a single array to produce a second harmonic output frequency, or a combination of multiple cascaded arrays configured to produce a selected higher order harmonic frequency.

Abstract: A hybrid laser source including a solid state laser driven by an array of fiber laser amplifiers, the inputs of which are controllable in phase and polarization, to compensate for distortions that arise in the solid state laser, or to achieve desired output beam properties relating to direction or focus. The output beam is sampled and compared with a reference beam to obtain phase and polarization difference signals across the output beam cross section, at spatial positions corresponding with the positions of the fiber laser amplifiers providing input to the solid state laser. Therefore, phase and polarization properties of the output beam may be independently controlled by predistortion of these properties in the fiber laser amplifier inputs.

Abstract: A laser array architecture scalable to very high powers by fiber amplifiers, but in which the output wavelength is selectable, and not restricted by the wavelengths usually inherent in the choice of fiber materials. A pump beam at a first frequency is amplified in the fiber amplifier array and is mixed with a secondary beam at a second frequency to yield a frequency difference signal from each of an array of optical parametric amplifiers. A phase detection and correction system maintains the array of outputs from the amplifiers in phase coherency, resulting in a high power output at the desired wavelength. A degenerate form of the architecture is disclosed in an alternate embodiment, and a third embodiment employs dual wavelength fiber amplifiers to obtain an output at a desired difference frequency.

Abstract: A high-energy optical beam generator providing a desired output waveform. The generator includes a master oscillator, such as a mode-locked laser, to generate an input beam, a first dispersive element to decompose the input beam into frequency components, a set of phase and amplitude modulators to modulate the frequency components individually, a set of power amplifiers to amplify the frequency components individually, and a second dispersive element to recombine the amplified and modulated frequency components into a single output beam. Phase control electronics control the modulators to provide the desired waveform for the output beam, based on its intended application and on sensed characteristics of the input beam and the output beam.

Abstract: An optical transmission system includes an optical source for providing an input optical signal to an optical array having a plurality of delay lines, and by utilizing orthogonal code modulation for active optical wave component control, the optical signal split among the plurality of delay lines is phase and amplitude modulated for efficient transmission to a destination point.

Abstract: A seed laser apparatus is disclosed. It comprises a distributed feedback laser system for transmitting a dithered optical signal having a frequency versus time characteristic that is represented by a triangular waveform and an optical medium including a plurality of optical signal paths, each path including an optical fiber and a fiber amplifier. The optical medium is characterized by stimulated Brillouin scattering (SBS) having a response time, whereby the period of the triangular waveform is equal to the round-trip transit time in the fiber or shorter than the response time of the SBS.

Abstract: An improved communication system which provides improved spectral efficiency as well as relatively low co-channel interference modulation characteristics relative to known communication systems. In particular, the communication system includes a modem that includes an arbitrary or chaotic waveform generator and a chaotic waveform demodulator configured as a sliding window correlator that is adapted to modulate and demodulate an arbitrary or chaotic waveforms. The modulator includes a finite impulse response (FIR) filter, for example, formed from tapped delay lines with unequal time delays. The demodulator is formed as a matched filter for recovery of the input data signals. The modem is adapted to transmit either optical or RF waveforms. In order to prevent drift of the tap weights due to temperature drift of the tapped delay lines and other factors, a closed servo loop may be provided for each tap weight.