Abstract: A fiber amplifier system including an optical component responsive to a seed beam and causing amplitude modulation that creates a non-uniform spectral transmission having peaks and nulls, and an actuator operable to shift the spectral transmission. The system further includes a fiber amplifier responsive to the seed beam and generating an amplified output beam and a beam sampler responsive to the output beam that provides a sample beam. A detector detects power fluctuations in the sample beam caused by the amplitude modulation, and generates a control metric identifying a magnitude of the fluctuations. A controller uses the control metric to control the actuator to cause it to make adjustments to the seed beam or to the optical component to cause the spectral transmission caused by the optical component to shift so that the peaks or nulls of the spectral transmission align with a center frequency of the seed beam.

Abstract: A fiber amplifier system including a plurality of optical components in an amplification chain that are responsive to a seed beam and that cause frequency modulation (FM) to amplitude modulation (AM) conversion to the seed beam that creates a non-uniform spectral transmission having a transmission function, where one of the optical components is a fiber amplifier generating an amplified output beam. A programmable spectral filter is controlled to pre-distort the seed beam by applying an inverse of the transmission function that creates a net uniform transmission function by equalizing a net spectral transmission profile of the seed beam at an end of the amplification chain to reduce the amplitude modulation.

Abstract: A fiber laser amplifier system that employs a technique for reducing polarization modulation instability (PMI) in a delivery fiber. The system includes a fiber amplifier that amplifies a seed beam and provides the amplified seed beam to a weakly polarization maintaining (PM) delivery fiber that delivers the amplified beam to a certain location. The polarization of the seed beam is controlled so that it aligns with the slow axis of the delivery fiber such that nonlinear birefringence that occurs in the delivery fiber is added to the natural birefringence of the delivery fiber so as to suppress the PMI in the delivery fiber.

Abstract: A fiber amplifier system including an optical source providing an optical seed beam and an FM electro-optic modulator (EOM) that frequency modulates the seed beam to broaden its spectral linewidth. The system also includes an AM EOM that modulates the seed beam to provide an amplitude modulated seed beam that is synchronized with the frequency modulated seed beam. The system also includes a non-linear fiber amplifier receiving the AM and FM modulated seed beam, wherein the amplitude modulated seed beam causes self-phase modulation in the fiber amplifier that phase modulates the seed beam as it is being amplified by the fiber amplifier that acts to cancel the spectral linewidth broadening caused by the frequency modulation.

Abstract: An optical fiber launcher assembly can include a low precision fiber array that outputs a plurality of optical signals from a given side that are input into an opposing side. The optical fiber launcher assembly can also include a corrective optic aligned with and spaced apart from the low precision fiber array. The plurality of optical signals output from the low precision array to the corrective optic have a given trajectory and optical signals output from the corrective optic have a substantially parallel trajectory different from the given trajectory.

Abstract: A fiber amplifier system including a plurality of seed beam sources each generating a seed beam at a different wavelength and a selection switch selectively outputting the seed beams on one or more outputs. The system also includes a plurality of fiber amplifiers each receiving one of the selected seed beams from the selection switch and a plurality of wavelength division multiplexers (WDMs) where a separate WDM receives an amplified beam from a fiber amplifier, each WDM providing the amplified beam on a separate output depending on the wavelength of the selected beam. The system further includes a plurality of beam directors each being coupled to each WDM, where one of the beam directors receives all of the amplified beams on the delivery fibers from each of the WDMs depending on the selected seed beam, each beam director combining the beams using CBC or SBC into a combined output beam.

Abstract: An optical system, such as a fiber laser amplifier, including a plurality of optical sources, such as fiber amplifiers, each generating a beam. In one embodiment, the system includes first and second diffraction gratings that correct the angle of the propagation direction of the beams to remove angular dispersion caused by a diffractive optical element (DOE). In another embodiment, the system includes a single diffraction grating, where the optical beams pass through the grating twice to also remove the angular dispersion caused by the DOE.

Abstract: An internally switched fiber laser amplifier is disclosed and claimed. The switch is integrated directly into the fiber amplifier, so that the output power from each fiber amplifier can be switched between N selectable output fibers with minimal (approx. 1%) loss. The switch may be a close coupled pump switch, a spherical mirror or a planar mirror. The fiber laser amplifier may switch both pump and source lights, or may switch only the pump light then combine it with the source light before sending it to a gain amplifier.

Abstract: A system includes N master oscillators to generate N master oscillator driving signals. The system includes N splitters to split each of the N master oscillator signals into M coherent signals with M being a positive integer greater than one. A modulator and fiber amplifier stage adjusts the relative phases of the M coherent signals and generates M×N amplified signals. The M×N amplified signals are aggregated into M clusters of N fibers. The system includes M spectral beam combination (SBC) modules to combine each of the M clusters. Each SBC module combines the M×N amplified signals at N wavelengths and generates M tiled output beams. Each SBC module employs a single dimensional (1D) fiber optic array to transmit one cluster of N amplified signals from the M signal clusters and generates one tiled output beam of the M tiled output beams.

Abstract: An output characteristic of a monotonic system is controlled using a plurality of adjustable inputs. The adjustments are controlled using a set of setpoints and a set of dither magnitudes. Each input's adjustment is controlled simultaneously using a setpoint and a dither around the setpoint. The dither values for each input have a zero mean and there is zero correlation between the dithers applied to different inputs. The changes in the output characteristic that result from the dithers are measured, and are used to create an adjustment value. The adjustment value is used to create a set of adjusted dither magnitudes. The set of adjusted dither magnitudes are added to a set of integrated prior adjusted dither magnitudes to create a set of setpoint adjustments. Adding the setpoint adjustments to corresponding setpoints creates a set of updated setpoints. This process is repeated so that the setpoints converge on a value that maximizes the output characteristic being controlled.

Abstract: A fiber amplifier system including a plurality of fiber amplifiers each receiving a fiber beam and a tapered fiber bundle (TFB) combiner including a plurality of input end fibers, a plurality of output end fibers and a center bundle portion, where each input end fiber is coupled to a separate one of the fiber amplifiers, and where the bundle portion combines all of the fiber beams into a single combined beam and each output end fiber being capable of receiving the combined beam separately from the other output end fibers. The system also includes a low non-linear delivery fiber coupled to an output end fiber of the TFB combiner and an optical output turret coupled to the delivery fiber opposite to the TFB combiner, wherein the non-linear delivery fiber is configured to reduce the effect of cross-phase modulation (XPM) instability in the delivery fiber.

Abstract: A seed beam source for a fiber amplifier system. The seed beam source includes a plurality of continuous wave master oscillator lasers, each generating a laser beam at a different wavelength and a plurality of switching modulators each receiving the laser beam from a particular one of the master oscillator lasers, where each switching modulator is electrically driven so as to output the laser beam as pulses based on a predetermined timing control. The seed beam source further includes an optical coupler responsive to the optical pulses from the plurality of switching modulators where the optical coupler only receives one of the optical pulses from the plurality of switching modulators at any particular point in time, and where the optical coupler continuously receives the optical pulses from the plurality of switching modulators and outputs an interleaved continuous optical seed beam including the pulses from all of the switching modulators.

Abstract: A fiber amplifier system including at least one seed source providing an optical seed beam and a harmonic driver providing a sinusoidal drive signal at a predetermined frequency. The system also includes a harmonic phase modulator that receives the seed beam and the drive signal, where the harmonic phase modulator frequency modulates the seed beam using the drive signal so as to remove optical power from a zeroth-order frequency of the seed beam and create sidebands separated by the frequency of the drive signal. A dispersion element receives the frequency modulated seed beam and provides temporal amplitude modulation to the seed beam and a nonlinear fiber amplifier receives the amplitude modulated seed beam from the dispersion element and amplifies the seed beam, where the dispersion element and the fiber amplifier combine to remove optical power from the sidebands and put optical power back into the zeroth-order frequency.

Abstract: A multichannel polarization stabilizer including a mixing device responsive to a sample beam and a reference beam that provides an in-phase signal including the mixed sample beam and reference beam having a relative phase of 0° and a quadrature phase signal including the mixed sample beam and reference beam having a relative phase of 90°. The stabilizer also includes a photodetector responsive to the quadrature phase signal that converts the quadrature phase signal to a quadrature phase electrical signal. A polarization demultiplexer circuit receives the quadrature phase electrical signal and measures the amplitude of a frequency tone in the sample beam and provides a polarization amplitude signal. A polarization controller receives the polarization amplitude signal and controls the reference beam to maximize the polarization amplitude signal.

Abstract: A multichannel optical system including a mixing device responsive to a sample beam and a reference beam that provides an in-phase signal including the mixed sample beam and reference beam having a relative phase of 0° and a quadrature phase signal including the mixed sample beam and reference beam having a relative phase of 90°. The system also includes a photodetector responsive to the quadrature phase signal that converts the quadrature phase signal to a quadrature phase electrical signal. A polarization demultiplexer circuit receives the quadrature phase electrical signal and measures the amplitude of a unique time-dependent phase dither profile having a zero time-averaged mean and a zero time-averaged correlation to the other phase dither profiles and provides a polarization amplitude signal. A polarization controller receives the polarization amplitude signal and controls the reference beam to maximize the polarization amplitude signal.

Abstract: A system and method for controlling polarization in a fiber amplifier is disclosed. A polarization dither waveform is applied to a polarization controller so that dithering does not trigger PI-HOMI (Polarization-Induced High Order Mode Instability). The dither waveform may have a period that is much less than the thermal diffusion time across the fiber amplifier core. The dither waveform may also have a slew rate (defined in degrees/second on the Poincaré sphere) that is much slower than the thermal diffusion time across the fiber amplifier core.

Abstract: A nested loop system for combining coherent laser beams, The system includes multiple laser amplifiers each configured for emitting one of the laser beams, an output beam splitter configured for sampling each laser beam and for coupling each sampled laser beam to an inner feedback loop module, an output beam sampler configured for splitting the combined beam into a primary and a sampled output beam and for coupling the sampled output beam to the inner feedback loop module, multiple inner loop phase modulators each paired with one of the laser amplifiers, and the inner feedback loop module. For each laser amplifier the inner feedback loop module is configured to use the sampled output beam and the sampled laser beam associated with that laser amplifier to create a different inner loop feedback signal and to couple that inner loop feedback signal to that laser amplifier paired inner loop phase modulator.

Abstract: In one embodiment, a system includes a master oscillator for generating a primary laser signal. A plurality of amplifiers amplifies a plurality of secondary laser signals and generates a plurality of amplified laser signals. A plurality of actuators adjusts a position, a beam angle, a path length, and a phase of the plurality of amplified laser signals. At least one control module controls the plurality of actuators that adjust the position, the beam angle, the path length, and the phase of the plurality of amplified laser signals. A combiner receives the amplified laser signals to generate a combined laser output signal. At least one filter samples the combined laser output signal to generate a plurality of phase errors as feedback for the control module to control at least one of the position, the beam angle, or the path length for the plurality of amplified laser signals.

Abstract: A pulsed fiber array laser system that has actively stabilized coherent beam combination (CBC) is disclosed. The active stabilization is accomplished using both piston phase control and intra-pulse phase control, allowing a much greater increase in pulse energy. Further stabilization using intra-pulse amplitude control is also disclosed. A chirp profile can be written on the output pulse to enable specific applications. An amplitude profile of the amplifier array may optionally be tailored to match to a reference electrical pulse. Using the current invention, a much smaller number of amplifier chains will be needed to achieve certain pulse energy, resulting in a system with lower complexity, lower cost, smaller size, less weight, and higher reliability.

Abstract: A nested loop system for combining coherent laser beams, The system includes multiple laser amplifiers each configured for emitting one of the laser beams, an output beam splitter configured for sampling each laser beam and for coupling each sampled laser beam to an inner feedback loop module, an output beam sampler configured for splitting the combined beam into a primary and a sampled output beam and for coupling the sampled output beam to the inner feedback loop module, multiple inner loop phase modulators each paired with one of the laser amplifiers, and the inner feedback loop module. For each laser amplifier the inner feedback loop module is configured to use the sampled output beam and the sampled laser beam associated with that laser amplifier to create a different inner loop feedback signal and to couple that inner loop feedback signal to that laser amplifier paired inner loop phase modulator.