Abstract: A laser system comprises: a seed oscillator, having a seed output; dispersive optics, operative to receive the seed output and divide the seed output into spectrally separate seed components; an array of individually addressable, phase adjustable laser amplifiers corresponding to the spectrally separate components, each laser amplifier receiving as its seed one of the spectrally separate seed components and producing one of the spectrally separate amplified components; and phase actuators controlling the individually addressable, phase adjustable laser amplifiers. A method of operating a laser system comprises: generating a seed signal; dividing the seed signal into spectrally separate component signals; amplifying the spectrally separate component signals; recombining the spectrally separate component signals into an amplified output; and controlling phases of the amplified spectrally separate component signals. Both single-pass and double-pass amplifier array versions are disclosed.

Abstract: A method and apparatus for two-dimensional wavelength beam combining of laser sources. In one example, an external cavity multi-wavelength laser includes an array of laser emitters each producing an optical beam having a specified wavelength, a grating stack comprising a plurality of first-order diffraction gratings arranged linearly in a first dimension, and a dispersive element. The laser further includes a cylindrical telescope that images the optical beams from the array of laser emitters onto the grating stack. A first cylindrical transform lens spatially overlaps the optical beams in a second dimension forming a first region of overlap at the grating stack. A second cylindrical transform lens spatially overlaps the optical beams from the grating stack in the first dimension forming a second region of overlap at the dispersive element. The dispersive element transmits a multi-wavelength output beam comprising the spatially overlapped optical beams from the array of laser emitters.

Abstract: Coherent beam combining of laser gain elements achieves high output power in a diffraction limited beam. An active beam combining system coherently combines optical beams emitted by semiconductor laser gain elements in an external resonant cavity configuration. A beam combiner in the resonant cavity combines the outputs of the laser gain elements into a single coherent output beam whose power is monitored by a photodetector. A processor uses the photodetector's output to adjust the phases of the respective optical beams emitted by the laser gain elements so as to increase or maximize the coherent output beam's power. The processor may vary the optical beams' phases according to a stochastic parallel gradient descent (SPGD) algorithm for active phase control. Experimental results show a beam combining efficiency of 81% with an upper limit of 90% or higher and without the scaling limits imposed on passive-phasing systems.

Abstract: A method and apparatus for providing a high peak power optical beam. The method includes interleaving pulse trains of different wavelengths and spatially and temporally overlapping the different wavelengths to produce an amplified output beam with very high peak power.

Abstract: Stimulating emission via thulium's lasing transition from the 3H4 manifold to the 3H6 manifold yields light at wavelength of about 820 nm. Unfortunately, excited thulium ions also transition from the 3H4 manifold to the long-lived 3F4 manifold, where they become trapped and can no longer participate in the lasing transition. If the enough of the thulium population becomes trapped in the 3F4 manifold, the gain medium becomes transparent at the pump wavelength, rendering population inversion difficult or impossible. Fortunately, the size of the population in the 3F4 manifold can be limited by selecting an appropriate crystal host and thulium doping concentration, pumping the thulium with pulses shorter than the 3F4 manifold's lifetime, cooling the gain medium to low temperature (e.g., 77 K), stimulating emission from the 3F4 manifold, upconversion pumping of the thulium from the 3F4 manifold to the 3H4 manifold, or transferring energy from thulium in the 3F4 manifold to a co-dopant.

Abstract: Stimulating emission via thulium's lasing transition from the 3H4 manifold to the 3H6 manifold yields light at wavelength of about 820 nm. Unfortunately, excited thulium ions also transition from the 3H4 manifold to the long-lived 3F4 manifold, where they become trapped and can no longer participate in the lasing transition. If the enough of the thulium population becomes trapped in the 3F4 manifold, the gain medium becomes transparent at the pump wavelength, rendering population inversion difficult or impossible. Fortunately, the size of the population in the 3F4 manifold can be limited by selecting an appropriate crystal host and thulium doping concentration, pumping the thulium with pulses shorter than the 3F4 manifold's lifetime, cooling the gain medium to low temperature (e.g., 77 K), stimulating emission from the 3F4 manifold, upconversion pumping of the thulium from the 3F4 manifold to the 3H4 manifold, or transferring energy from thulium in the 3F4 manifold to a co-dopant.

Abstract: A method and apparatus for two-dimensional wavelength beam combining of laser sources. In one example, an external cavity multi-wavelength laser includes an array of laser emitters each producing an optical beam having a specified wavelength, a grating stack comprising a plurality of first-order diffraction gratings arranged linearly in a first dimension, and a dispersive element. The laser further includes a cylindrical telescope that images the optical beams from the array of laser emitters onto the grating stack. A first cylindrical transform lens spatially overlaps the optical beams in a second dimension forming a first region of overlap at the grating stack. A second cylindrical transform lens spatially overlaps the optical beams from the grating stack in the first dimension forming a second region of overlap at the dispersive element. The dispersive element transmits a multi-wavelength output beam comprising the spatially overlapped optical beams from the array of laser emitters.

Abstract: Extreme ultraviolet radiation is generated based on high-order harmonic generation. First, a driver pulse is generated from a drive laser. Second, the infrared driver pulse is passed through a second harmonic generator with an output wavelength in the range from 400 to 700 nm. Third, the pulse is then passed through a gas medium, which can be inside a resonant cavity, to generate a high-order harmonic in the form of extreme ultraviolet radiation.

Abstract: A method and apparatus for providing a high peak power optical beam. The method includes interleaving pulse trains of different wavelengths and spatially and temporally overlapping the different wavelengths to produce an amplified output beam with very high peak power.

Abstract: A method and apparatus for two-dimensional wavelength beam combining of laser sources. In one example, an external cavity multi-wavelength laser includes an array of laser emitters each producing an optical beam having a specified wavelength, a grating stack comprising a plurality of first-order diffraction gratings arranged linearly in a first dimension, and a dispersive element. The laser further includes a cylindrical telescope that images the optical beams from the array of laser emitters onto the grating stack. A first cylindrical transform lens spatially overlaps the optical beams in a second dimension forming a first region of overlap at the grating stack. A second cylindrical transform lens spatially overlaps the optical beams from the grating stack in the first dimension forming a second region of overlap at the dispersive element. The dispersive element transmits a multi-wavelength output beam comprising the spatially overlapped optical beams from the array of laser emitters.

Abstract: A method and apparatus for providing a high peak power optical beam. The method includes interleaving pulse trains of different wavelengths and spatially and temporally overlapping the different wavelengths to produce an amplified output beam with very high peak power.

Abstract: An external-cavity one-dimensional multi-wavelength beam combiner that performs wavelength beam combining along a stacking dimension of a laser stack formed of a plurality of laser arrays, each laser array configured to generate optical radiation having a unique wavelength, and each of the plurality of laser arrays including one or more laser emitters arranged along an array dimension of the laser stack. The multi-wavelength beam combiner includes an optical imaging element configured to image each of the laser emitters along a slow axis of the laser emitters, an optical focusing element arranged to intercept the optical radiation from each of the plurality of laser arrays and combine the optical radiation along a stacking dimension of the laser stack to form a multi-wavelength optical beam, and a diffraction element positioned at a region of overlap of the optical radiation to receive and transmit the multi-wavelength optical beam.

Abstract: A solid-state gain element including a thin doped region in which an optical signal propagates through the thin doped region at a large angle with respect to the normal to the thin doped region, reflects at a boundary of the thin doped region, and passes through the thin doped region again. An optical pump beam propagates through the thin doped region also at a large angle with respect to the normal to the thin doped region. In one example, the gain element and source of the pump beam are configured such that there is total internal reflection of the pump beam at the boundary of the thin doped region for a second pumping pass through the thin doped region. In another example, an elliptically symmetric laser beam is used to create a circularly symmetric gain region in the thin doped region.

Abstract: A laser system comprises: a seed oscillator, having a seed output; dispersive optics, operative to receive the seed output and divide the seed output into spectrally separate seed components; an array of individually addressable, phase adjustable laser amplifiers corresponding to the spectrally separate components, each laser amplifier receiving as its seed one of the spectrally separate seed components and producing one of the spectrally separate amplified components; and phase actuators controlling the individually addressable, phase adjustable laser amplifiers. A method of operating a laser system comprises: generating a seed signal; dividing the seed signal into spectrally separate component signals; amplifying the spectrally separate component signals; recombining the spectrally separate component signals into an amplified output; and controlling phases of the amplified spectrally separate component signals. Both single-pass and double-pass amplifier array versions are disclosed.

Abstract: An external-cavity one-dimensional multi-wavelength beam combiner that performs wavelength beam combining along a stacking dimension of a laser stack formed of a plurality of laser arrays, each laser array configured to generate optical radiation having a unique wavelength, and each of the plurality of laser arrays including one or more laser emitters arranged along an array dimension of the laser stack. The multi-wavelength beam combiner includes an optical imaging element configured to image each of the laser emitters along a slow axis of the laser emitters, an optical focusing element arranged to intercept the optical radiation from each of the plurality of laser arrays and combine the optical radiation along a stacking dimension of the laser stack to form a multi-wavelength optical beam, and a diffraction element positioned at a region of overlap of the optical radiation to receive and transmit the multi-wavelength optical beam.

Abstract: A method and apparatus for providing a high peak power optical beam. The method includes interleaving pulse trains of different wavelengths and spatially and temporally overlapping the different wavelengths to produce an amplified output beam with very high peak power.

Abstract: A method of operating a high-output-power fiber laser system includes: time multiplexing a plurality of pulses, each pulse having a pulse width, and each having a different wavelength from a plurality of seed oscillators onto a single fiber; setting each pulse width to a width less than the phonon lifetime; separating in time each pulse from each other pulse so as to leave a gap between adjacent pulses; setting a time between pulses each having a common wavelength to a time longer than a round-trip time of flight through a fiber amplifier of pulses having the common wavelength; and injecting the plurality of pulses from the single fiber into the fiber amplifier. Also to disclosed is a system capable of performing the method.

Abstract: An external-cavity one-dimensional multi-wavelength beam combiner that performs wavelength beam combining along a stacking dimension of a laser stack formed of a plurality of laser arrays, each laser array configured to generate optical radiation having a unique wavelength, and each of the plurality of laser arrays including a plurality of laser emitters arranged along an array dimension of the laser stack. The multi-wavelength beam combiner includes a cylindrical telescope configured to image each of the laser emitters along a slow axis of the laser emitters, a transform lens arranged to intercept the optical radiation from each of the plurality of laser arrays and combine the optical radiation along a stacking dimension of the laser stack to form a multi-wavelength optical beam, and a diffraction element positioned at a region of overlap of the optical radiation to receive and transmit the multi-wavelength optical beam.

Abstract: A method and apparatus for two-dimensional wavelength beam combining of laser sources. In one example, an external cavity multi-wavelength laser includes an array of laser emitters each producing an optical beam having a specified wavelength, a grating stack comprising a plurality of first-order diffraction gratings arranged linearly in a first dimension, and a dispersive element. The laser further includes a cylindrical telescope that images the optical beams from the array of laser emitters onto the grating stack. A first cylindrical transform lens spatially overlaps the optical beams in a second dimension forming a first region of overlap at the grating stack. A second cylindrical transform lens spatially overlaps the optical beams from the grating stack in the first dimension forming a second region of overlap at the dispersive element. The dispersive element transmits a multi-wavelength output beam comprising the spatially overlapped optical beams from the array of laser emitters.

Abstract: Extreme ultraviolet radiation is generated based on high-order harmonic generation. First, a driver pulse is generated from a drive laser. Second, the infrared driver pulse is passed through a second harmonic generator with an output wavelength in the range from 400 to 700 nm. Third, the pulse is then passed through a gas medium, which can be inside a resonant cavity, to generate a high-order harmonic in the form of extreme ultraviolet radiation.