Abstract: In one of the embodiments, a dark channel array is provided which includes gain channels, each configured to emit an output beam from an output surface and to have a light wave propagating therethrough. It further includes a dark channel configured to emit an output beam from the output surface of the dark channel array and to have a light wave propagating in the dark channel, such that output beams from the plurality of gain channels are coherently coupled in phase with each other. The dark channel array is configured such that the dark channel captures a portion of the output beam from at least two of the plurality of gain channels by radiant coupling.

Abstract: Systems and methods for pre-correcting accumulated optical nonlinear phase error in a shaped optical pulse derived from a continuous wave laser signal are provided. A continuous wave laser signal is received. A pulse signal is received. A shaped optical pulse is generated from the continuous wave laser signal upon being driven by the pulse signal. A pulse intensity level to be applied to the phase of the shaped optical pulse is received. A phase correcting signal is generated based on the pulse intensity level. Application of the phase correcting signal to the shaped optical pulse is time-synchronized and the phase correcting signal is applied to the shaped optical pulse to generate a pre-corrected shaped optical pulse.

Abstract: An optical coupler is provided for a passive coherent combination of fiber lasers/amplifiers. A plurality of optical fibers are arranged in a close-packed hexagonal array having 1+3n(n+1) fibers with (3/2)(n2?n)+3 interferometrically dark fibers and (3/2)(n2+3n)?2 light fibers, where n is an integer greater than or equal to 1. Each optical fiber has a first end and a second end. The plurality of optical fibers are fused together along a section of each optical fiber proximate the first end of each optical fiber to form a fused section having a fiber axis. The fused section of the plurality of optical fibers is tapered to form a tapered region. A facet is at an end of the fused section. The facet is disposed in a direction perpendicular to the fiber axis. The coherent pattern is highly stable against perturbation.

Abstract: Systems and methods for pre-correcting accumulated optical nonlinear phase error in a shaped optical pulse derived from a continuous wave laser signal are provided. A continuous wave laser signal is received. A pulse signal is received. A shaped optical pulse is generated from the continuous wave laser signal upon being driven by the pulse signal. A pulse intensity level to be applied to the phase of the shaped optical pulse is received. A phase correcting signal is generated based on the pulse intensity level. Application of the phase correcting signal to the shaped optical pulse is time-synchronized and the phase correcting signal is applied to the shaped optical pulse to generate a pre-corrected shaped optical pulse.

Abstract: In one embodiment, a dark channel array is provided which includes gain channels, each gain channel being configured to emit an output beam, and which includes a dark channel configured to cause output beams from the gain channels to be coherently couple in phase with each other.

Abstract: An optical fiber has a concentration of dopant ions residing within its core region. The dopant ions absorb optical energy at an excitation wavelength, converting that optical energy to heat and/or a change in the index of refraction and optical length of the optical fiber. Optical energy of the excitation wavelength is transmitted through the optical fiber simultaneously or sequentially with optical energy of a signal wavelength different from the excitation wavelength. The optical energy of the excitation wavelength controls the temperature of the optical fiber and/or its optical length as a result of (a) the temperature dependence of the refractive index and the physical length of the optical fiber, and (b) the change in polarizability of the optical fiber medium (and hence its refractive index) due to a change in the population distribution among the energy levels of the dopant ions.

Abstract: A high power Er-doped fiber amplifier/laser system includes a cladding-pumped fiber grating laser that emits an output beam at a wavelength that falls within an absorption band of erbium. The fiber grating laser output beam is used as the pumping source for an Er-doped fiber amplifier or laser. Because the output from the fiber grating laser falls within one of the erbium absorption bands, the amplifier or laser may be directly pumped with the fiber grating laser's output without the need for co-doping. In a preferred embodiment, the fiber grating laser is a 980 nm ytterbium-doped fiber grating laser that is cladding-pumped with a multi-transverse mode diode laser array. The Yb-doped fiber grating laser and the Er-doped fiber amplifier/laser are preferably spliced directly to an input and output arm of a WDM fiber coupler, respectively.

Abstract: A narrow bandwidth Bragg grating reflector comprises at least two Bragg reflection gratings positioned to form a Fabry-Perot etalon, with an optical gain medium between them. The etalon formed by the Bragg gratings has a reflection frequency spectrum that exhibits a plurality of primary peaks and nulls. The distance between the Bragg gratings is adjusted so that a predetermined design frequency falls within the bandwidth of one of the nulls, and the optical gain medium is chosen to provide optical gain for light at the design frequency. This establishes a secondary reflection peak in the Bragg grating etalon, centered on the design frequency, with a bandwidth that is narrower than those of the individual Bragg gratings and primary reflection peaks. In a preferred embodiment, the Bragg gratings are formed in the core of an optical fiber that is doped to provide optical gain at the predetermined optical frequency.

Abstract: An laser radar system employing transmitted random and pseudo random optical pulse trains and signal processing that provides unambiguous range and Doppler velocity data. The system comprises a diode-pumped fiber laser local oscillator and an optical random pulse signal generator comprising a mode-locked fiber laser source for generating and transmitted randomly spaced optical pulses. A heterodyne output pulse monitor processes the local oscillator signals and samples the transmitted optical pulses. A heterodyne receiver detector processes the local oscillator signals and received optical pulses reflected from a target. An acoustic charge transport delay line provides a selectable signal delay for the signal provided by the heterodyne optical pulse monitor, and a mixer mixes signals provided by the heterodyne receiver detector and delay line and provides correlation output signals.

Abstract: A passively controlled multiple output fiber laser system in which the frequency relationships between all of the optical outputs remain constant over time includes a plurality of fiber lasers for generating respective output beams. The lasers are positioned in close proximity to each other so that they experience the same environmental conditions. Each laser includes at least one Bragg reflection grating that controls the frequency and bandwidth of the laser's output beam. The Bragg gratings are formed so that they respond equally to environmental changes. In a preferred embodiment, the fiber lasers are made from a plurality of substantially identical photosensitive fibers, and Bragg gratings are exposed simultaneously under identical exposure conditions in each of the fibers. A multiple output fiber laser system suitable for heterodyne LADAR systems is also provided.

Abstract: A passively mode-locked laser and method for generating a coherent pseudo random pulse train is disclosed. The laser comprises an optical resonant cavity that is capable of sustaining the oscillation of a plurality of resonant modes having respective phases. A saturable absorber is positioned in the resonant cavity and has an optical intensity threshold beyond which multiple mode-locked pulses with random starting times are generated in the resonant cavity and periodically emitted by the laser. A pump injects power into the resonant cavity at a level at which the optical intensity that is incident on the saturable absorber exceeds the optical intensity threshold.

Abstract: A laser apparatus (10) has a coherent master oscillator radiation source (30) for driving a plurality of laser gain elements (20) positioned in a operationally parallel configuration so as to receive unamplified radiation (40) from master oscillator (30) and transmitting amplified radiation (44). Input means (60) couples portion of radiation (40) from master oscillator to each of said gain elements (20). Phase conjugate reflector means (80) operatively coupled to gain elements (20) reflects the phase conjugate of amplified radiation (44) back into the gain elements (20) where it is further amplified. Output coupling means (90) couples amplified radiation from the plurality of gain elements (20) out of the laser apparatus as a single coherent output beam of radiation.