Abstract: A method for amplifying an optical seed beam in a fiber laser amplifier system. The method includes frequency modulating the seed beam to a carrier spectral band, amplitude modulating the seed beam that is synchronized with the frequency modulated seed beam, amplifying the seed beam using a pump power beam to provide an output beam where most of the beam power resides in the carrier spectral band, sampling off a sample beam from the output beam, filtering out the carrier spectral band from the sample beam, detecting beam power of the filtered sample beam and providing a beam power signal, and controlling one or more of the frequency modulation of the seed beam, the amplitude modulation of the seed beam and the pump power beam to change an FM modulation depth, an AM modulation depth and/or pump beam power in a manner that reduces the beam power signal.

Abstract: A fiber laser amplifier system including a first dual-clad delivery fiber receiving a signal beam and a pump beam, a doped amplifying fiber coupled to the first delivery fiber and receiving the signal beam and the pump beam, and amplifying the signal beam using the pump beam, and a second dual-clad delivery fiber coupled to the amplifying fiber and receiving the amplified signal beam and the pump beam. The system also includes an endcap having an input facet and an output facet. The input facet is coupled to the second delivery fiber and receives the amplified signal beam and the pump beam, and the output facet is configured to pass the amplified signal beam and reflect the pump beam back onto the second delivery fiber to be directed back to the doped amplifying fiber.

Abstract: A method for amplifying an optical seed beam in a fiber laser amplifier system. The method includes frequency modulating the seed beam to a carrier spectral band, amplitude modulating the seed beam that is synchronized with the frequency modulated seed beam, amplifying the seed beam using a pump power beam to provide an output beam where most of the beam power resides in the carrier spectral band, sampling off a sample beam from the output beam, filtering out the carrier spectral band from the sample beam, detecting beam power of the filtered sample beam and providing a beam power signal, and controlling one or more of the frequency modulation of the seed beam, the amplitude modulation of the seed beam and the pump power beam to change an FM modulation depth, an AM modulation depth and/or pump beam power in a manner that reduces the beam power signal.

Abstract: A fiber laser amplifier system including a non-linear fiber amplifier receiving a seed beam and a pump beam, where the amplifier amplifies the seed beam using the pump beam to provide an output beam having a carrier spectrum. A beam sampler samples off a sample beam from the output beam, a filter receives the sample beam and filters out the carrier spectrum from the sample beam, a photodetector detects beam power of the filtered sample beam and provides a beam power signal, and a controller receives the beam power signal, where the controller controls one or more of an FM drive signal, an AM drive signal and a pump beam to change seed beam FM modulation, seed beam AM modulation and/or pump power in a manner that reduces the beam power of the filtered sample beam and thus beam power outside of the carrier spectrum.

Abstract: A fiber laser amplifier system including a first dual-clad delivery fiber receiving a signal beam and a pump beam, a doped amplifying fiber coupled to the first delivery fiber and receiving the signal beam and the pump beam, and amplifying the signal beam using the pump beam, and a second dual-clad delivery fiber coupled to the amplifying fiber and receiving the amplified signal beam and the pump beam. The system also includes an endcap having an input facet and an output facet. The input facet is coupled to the second delivery fiber and receives the amplified signal beam and the pump beam, and the output facet is configured to pass the amplified signal beam and reflect the pump beam back onto the second delivery fiber to be directed back to the doped amplifying fiber.

Abstract: A fiber laser amplifier system including a non-linear fiber amplifier receiving a seed beam and a pump beam, where the amplifier amplifies the seed beam using the pump beam to provide an output beam having a carrier spectrum. A beam sampler samples off a sample beam from the output beam, a filter receives the sample beam and filters out the carrier spectrum from the sample beam, a photodetector detects beam power of the filtered sample beam and provides a beam power signal, and a controller receives the beam power signal, where the controller controls one or more of an FM drive signal, an AM drive signal and a pump beam to change seed beam FM modulation, seed beam AM modulation and/or pump power in a manner that reduces the beam power of the filtered sample beam and thus beam power outside of the carrier spectrum.

Abstract: A technique for compensating for the effects of thermo-optic distortions in a solid state laser gain medium, and reducing optical path differences in the laser. A diode array coupled to the laser gain medium is selectively modulated to provide pump power, the intensity of which varies across the aperture of the gain medium. The modulated diode array has a spatial power profile that is selected to compensate for thermal distortions arising from various causes. The modulated diode array may be one of several diode arrays providing pump power to the laser gain medium, or may be an auxiliary diode array with the sole purpose of providing compensating power input with a selected profile across the aperture of the gain medium.

Abstract: A solid state zig-zag slab laser amplifier in which depolarization occurring at total internal reflection from opposed lateral faces of the amplifier slab is controlled by selecting a complex evanescent coating that provides a selected phase retardance that results in minimization of depolarization. Without use of the complex coating, small changes in incidence angles can result in phase retardance changes large enough to increase depolarization significantly, especially when the amplifier is operated at higher powers. Appropriate selection of the complex evanescent coating allows a desired phase retardance angle to be maintained relatively constant over a small range of angles of incidence, at a given wavelength, and therefore permits minimization of depolarization and birefringence effects.