Abstract: Swept source optical coherence tomography (SS-OCT) systems and methods may employ down-conversion. Down-converter systems and methods may utilize a distribution element and a frequency down shifter. The distribution element may receive an output signal of a photo detection device, the output signal comprising a first frequency component at or below a maximum conversion frequency and a second frequency component above the maximum conversion frequency. The distribution element may send the first frequency component to an analog to digital (A/D) converter and send the second frequency component to a frequency down shifter. The frequency down shifter may down shift the second frequency component to a frequency at or below the maximum conversion frequency to form a down shifted second frequency component. The frequency down shifter may send the down shifted second frequency component to the A/D converter.

Abstract: Swept source optical coherence tomography (SS-OCT) systems and methods may employ down-conversion. Down-converter systems and methods may utilize a distribution element and a frequency down shifter. The distribution element may receive an output signal of a photo detection device, the output signal comprising a first frequency component at or below a maximum conversion frequency and a second frequency component above the maximum conversion frequency. The distribution element may send the first frequency component to an analog to digital (A/D) converter and send the second frequency component to a frequency down shifter. The frequency down shifter may down shift the second frequency component to a frequency at or below the maximum conversion frequency to form a down shifted second frequency component. The frequency down shifter may send the down shifted second frequency component to the A/D converter.

Abstract: Swept source optical coherence tomography (SS-OCT) systems and methods may employ down-conversion. Down-converter systems and methods may utilize a distribution element and a frequency down shifter. The distribution element may receive an output signal of a photo detection device, the output signal comprising a first frequency component at or below a maximum conversion frequency and a second frequency component above the maximum conversion frequency. The distribution element may send the first frequency component to an analog to digital (A/D) converter and send the second frequency component to a frequency down shifter. The frequency down shifter may down shift the second frequency component to a frequency at or below the maximum conversion frequency to form a down shifted second frequency component. The frequency down shifter may send the down shifted second frequency component to the A/D converter.

Abstract: A desired Nth-order Stokes output and zeroth-order Stokes pump input are seeded into a rare-earth doped amplifier where the power of the zeroth-order Stokes signal is amplified prior to both signals entering a Raman amplifier comprised of N?1 Raman resonators, each uniquely tuned to one of the N?1 Stokes orders, in various configurations to include one or more nested and/or in-series Raman resonators. The zeroth-order Stokes signal is converted to the Nth?1-order Stokes wavelength in steps and the power level of the Nth-order Stokes wavelength is amplified as the two signals propagate through the Raman resonators. Each Raman resonator includes a photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the Stokes orders can be controlled by offsetting the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

Abstract: Swept source optical coherence tomography (SS-OCT) systems and methods may employ down-conversion. Down-converter systems and methods may utilize a distribution element and a frequency down shifter. The distribution element may receive an output signal of a photo detection device, the output signal comprising a first frequency component at or below a maximum conversion frequency and a second frequency component above the maximum conversion frequency. The distribution element may send the first frequency component to an analog to digital (A/D) converter and send the second frequency component to a frequency down shifter. The frequency down shifter may down shift the second frequency component to a frequency at or below the maximum conversion frequency to form a down shifted second frequency component. The frequency down shifter may send the down shifted second frequency component to the A/D converter.

Abstract: A third-order Stokes wavelength seed signal at the desired output wavelength of 1240 nm and a zeroth-order Stokes wavelength signal at 1066 nm are input into a Raman amplifier comprised of two Raman resonators in a linear configuration. The first resonator converts the zeroth-order Stokes wavelength signal at 1066 nm into a first-order Stokes wavelength signal at 1118 nm, and also outputs the third-order Stokes wavelength seed signal at 1240 nm. The second resonator then converts the 1118 nm output from the first resonator into a second-order Stokes wavelength signal at 1176 nm, which amplifies the 1240 nm seed signal power level. Each Raman resonator includes a photosensitive Raman fiber communicating with a plurality of high-reflector Bragg gratings. The linewidths of the second and third Stokes orders are controlled by adjusting the resonant bandwidth of the second Raman resonator by offsetting the respective center wavelengths of the high-reflector Bragg gratings.

Abstract: A third-order Stokes signal at the desired output wavelength of 1240 nm and a zeroth-order Stokes pump wavelength at 1066 nm are seeded into a Raman amplifier comprised of two nested resonators tuned to the first-order Stokes line at 1118 nm and second-order Stokes line at 1176 nm, respectively. The pump wavelength is first amplified and then sequentially converted into the first and second-order Stokes wavelengths as the light traverses the nested resonators. The desired third-order Stokes output wavelength is then amplified by the second-order Stokes wavelength as it propagates through the outermost resonator. Each Raman resonator includes a photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the various Stokes orders can be controlled through adjusting the resonant bandwidths of the Raman resonators by offsetting, through heating, the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

Abstract: A desired Nth-order Stokes output and corresponding zeroth-order Stokes pump wavelengths are seeded into a Raman amplifier comprised of one or more Raman resonators in series sequentially tuned to the 1st, 2nd, . . . N?1st Stokes orders. The pump wavelength is amplified and sequentially converted to the 1st, 2nd, . . . N?1st order Stokes wavelengths as it propagates through the apparatus. The desired Nth-order Stokes output wavelength is then amplified by the N?1st Stokes order as it propagates through the final resonator tuned to the N?1st Stokes order. Each Raman resonator includes a Raman photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the various Stokes orders can be controlled through adjusting the resonant bandwidths of the Raman resonators by offsetting, through heating, the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

Abstract: A broad linewidth, zeroth Stokes order 1069 nm pump and a narrow linewidth second Stokes order 1178 nm seed propagate through a wavelength division multiplexer and then through a rare-earth-doped amplifier. After passing through a 1121 nm long period or tilted Bragg grating, the amplified 1069 nm Stokes signal and the 1178 Stokes signal are injected into a 1121 nm resonator Raman cavity, which includes a pair of highly reflective Bragg gratings having a center wavelength of 1121 nm. The amplified 1069 nm Stokes signal is Raman converted to high power levels of 1121 nm which then, in turn, amplifies the 1178 nm Stokes seed as it traverses the cavity. The linewidth of the amplified 1178 nm Stokes signal can be controlled by offsetting, through heating, the reflectivity bandwidth of the Bragg grating located near the output end of the Raman cavity.

Abstract: A method of implementing a high-power coherent laser beam combining system in which the output of a master oscillator laser having a linewidth broader than the Stimulated Brillouin Scattering linewidth of the laser signal is split into N signals and fed into an array of N optical fibers. This is a modification of the self-synchronous LOCSET and self-referenced LOCSET phase matching systems in which the optical path length of each optical fiber is matched to less than the signal coherence length of the master oscillator by using a path length matching signal processor to modulate temperature controlled segments of each optical fiber.

Abstract: A method of generating high-power laser output in the 1100 to 1500 um spectral region having a controllable linewidth. A Raman amplifier comprised of one or more nested pairs of fiber Bragg grating cavities tuned to the 1st, 2nd, . . . N?1st order Stokes wavelengths is seeded with both the desired Nth order Stokes output wavelength and the corresponding zeroth-order Stokes pump wavelength. As the pump wavelength propagates through the apparatus, it is sequentially converted to the 1st, 2nd, . . . N?1st order Stokes wavelengths in the nested fiber Bragg grating cavities. The desired Nth order Stokes output wavelength is then amplified by the N?1st Stokes order as it propagates through the nested fiber Bragg grating cavities. The linewidths of various Stokes orders can be controlled through adjusting resonant bandwidths of the fiber Bragg grating cavities by offsetting, through heating, the reflectivity bandwidths of each pair of cavity gratings.

Abstract: Stimulated Brillouin scattering (SBS) in a photonic crystal fiber is suppressed by doping the individual core segments such that the Brillouin frequency of each segment is sufficiently different from the neighboring segments that Brillouin scattered light from one core segment sees negligible gain from the other core segments, whereby higher power narrow-linewidth optical fiber amplifiers and lasers may be obtained. The optical properties of the guiding medium are preserved through the careful design of the core and the lattice structure.

Abstract: A method and system whereby a narrow linewidth coherent laser source when transmitted as a plurality of output signals and subsequently detected at a distance appears to produce the uniform illumination characteristics of an incoherent source thereby suppressing laser speckle and environmentally induced scintillation effects. A master oscillator source is split into N signals, each of which is independently phase modulated by frequencies designed to minimize a derived apparent incoherence factor. The signals are then either directed to an object to be illuminated so that they overlap at the object or first recombined and directed to the object.

Abstract: A method to increase the output power of narrow-linewidth rare earth-doped fiber amplifiers by suppressing simulated Brillouin scattering. The fiber amplifier is seeded with two or more lasers having frequencies and input powers that are sufficiently different. The seed signal with the highest emission cross section (e.g., signal 2) initially experiences the greatest gain. If signal 2 is also given sufficiently greater input power than signal 1, it will be amplified to its maximum value before the seed signals have reached the midpoint of the gain fiber. Beyond that point, the signal having the lower emission and absorption cross sections (signal 1) and significantly lower input power will continue to experience gain by power transfer from both signal 2 and the pump light, attaining a power output well beyond what the maximum output would have been had the amplifier been illuminated with a single frequency beam.

Abstract: A coherent laser beam combining system wherein the output of a single master oscillator is split into a plurality of signals, the signals are electronically modulated at unique frequencies. One signal is designated a reference signal while the remaining signals are passed through phase adjusters. All signals are optically amplified, aligned and passed through a beam splitter to split off a small sample that is imaged onto a photodetector. The photodetector output is fed to a signal processor that produces phase error signals that drive the phase adjusters resulting in a high-powered optically coherent output signal.

Abstract: A coherent laser beam combining system wherein the output of a single master oscillator is split into a plurality of signals, the signals are electronically modulated at unique frequencies. One signal is designated a reference signal while the remaining signals are passed through phase adjusters. All signals are optically amplified, aligned and passed through a beam splitter to split off a small sample that is imaged onto a photodetector. The photodetector output is fed to a signal processor that produces phase error signals that drive the phase adjusters resulting in a high-powered optically coherent output signal.

Abstract: A coherent laser beam combining system wherein the output of a single master oscillator is split into a plurality of N signals, and the N signals are electronically modulated at unique frequencies. There is no reference signal and all of the signals are passed through phase adjusters. All N signals are optically amplified, aligned and passed through a beam splitter to split off a small sample that is imaged onto a photodetector. The photodetector output is fed to a signal processor that separates the N signals and produces N phase error signals that drive the N phase adjusters resulting in a high-powered optically coherent output signal.

Abstract: A method of full-duplex electromagnetic communication wherein a pair of data modulation formats are selected for the forward and return data links respectively such that the forward data electro-magnetic beam serves as a carrier for the return data. A method of encoding optical information is used wherein right-hand and left-hand circular polarizations are assigned to optical information to represent binary states. An application for an earth to low earth orbit optical communications system is presented which implements the full-duplex communication and circular polarization keying modulation format.

Abstract: A method and apparatus for enhanced optical emissions, the apparatus comprising a light source, a microcavity, and a medium comprising nanoparticles, located within or near the microcavity. The nanoparticles are either non-aggregated or are aggregated in the form of fractals. The nanoparticles and microcavity exhibit enhanced linear and non-linear optical emission. The light emitting apparatus can be used for wavelength translation, amplification, optical parametric oscillation, light detection and ranging, increased sensitivity, high density optical data storage, and near-field optical spectroscopy.

Abstract: An apparatus and method wherein polarization rotation in alkali vapors or other mediums is used for all-optical switching and digital logic and where the rate of operation is proportional to the amplitude of the pump field. High rates of speed are accomplished by Rabi flopping of the atomic states using a continuously operating monochromatic atomic beam as the pump.