Abstract: An IR supercontinuum source for generating supercontinuum in the MIR or possibly LWIR spectral bands comprises a supercontinuum fiber formed from a heavy metal oxide host glass having low optical loss and high non-linearity over the spectral band that is stable, strong and chemically durable. The supercontinuum fiber is suitably a depressed inner clad fiber configured to support only single transverse spatial mode propagation of the pump signal and supercontinuum. The source suitably includes a tapered depressed inner clad fiber to couple the pump signal into the supercontinuum fiber. The source may be configured as an “all-fiber” source.

Abstract: An IR supercontinuum source for generating supercontinuum in the MIR or possibly LWIR spectral bands comprises a supercontinuum fiber formed from a heavy metal oxide host glass having low optical loss and high non-linearity over the spectral band that is stable, strong and chemically durable. The supercontinuum fiber is suitably a depressed inner clad fiber configured to support only single transverse spatial mode propagation of the pump signal and supercontinuum. The source suitably includes a tapered depressed inner clad fiber to couple the pump signal into the supercontinuum fiber. The source may be configured as an “all-fiber” source.

Abstract: A tellurium oxide glass that is stable, strong and chemically durable exhibits low optical loss from the UV band well into the MIR band. Unwanted absorption mechanisms in the MIR band are removed or reduced so that the glass formulation exhibits optical performance as close as possible to the theoretical limit of a tellurium oxide glass. The glass formulation only includes glass constituents that provide the intermediate, modifiers and any halides (for OH— reduction) whose inherent absorption wavelength is longer than that of Tellurium (IV) oxide. The glass formulation is substantially free of Sodium Oxide and any other passive glass constituent including hydroxyl whose inherent absorption wavelength is shorter than that of Tellurium (IV) oxide. The glass formulation preferably includes only a small residual amount of halide.

Abstract: A tellurium oxide glass that is stable, strong and chemically durable exhibits low optical loss from the UV band well into the MIR band. Unwanted absorption mechanisms in the MIR band are removed or reduced so that the glass formulation exhibits optical performance as close as possible to the theoretical limit of a tellurium oxide glass. The glass formulation only includes glass constituents that provide the intermediate, modifiers and any halides (for OH— reduction) whose inherent absorption wavelength is longer than that of Tellurium (IV) oxide. The glass formulation is substantially free of Sodium Oxide and any other passive glass constituent including hydroxyl whose inherent absorption wavelength is shorter than that of Tellurium (IV) oxide. The glass formulation preferably includes only a small residual amount of halide.

Abstract: A phosphate glass 1-?m fiber ASE source provides high power and broadband emission that covers wavelengths on the short side of Yb-doped silica. A single-mode fiber formed from phosphate glass is doped with highly elevated concentrations of Yb dopants 0.5-30 wt. % and typically 2-10 wt. %, far higher than either silica or germano-silicate. The high concentration of Yb dopant absorbs the pump in a short length, typically 10-150 cm instead of tens of meters, to provide high saturated output power and a shifted emission spectrum. The excess power allows the fiber ASE source to be configured to provide the output powers, emission bandwidth and stability desired by many applications. Furthermore, the ASE can be configured to emit a nearly Gaussian spectral profile without sacrificing power or bandwidth.

Abstract: A shared modulator applies radial stress to the polarization-dependent fiber chains to induce birefringence and simultaneously Q-switch two or more fiber lasers. Multiple temporally overlapping pulsed beams can be generated with pulses <100 ns and even <30 ns with repetition rates from 50 Hz up to 650 KHz. A pair of Q-switched fiber lasers at slightly different wavelengths being well suited to provide a low-frequency light source through difference frequency generation (DFG) by nonlinear optical materials.

Abstract: A fiber-laser-based implementation of a Gigahertz source through difference frequency generation (DFG) by nonlinear optical (NLO) materials is compact, tunable and scalable. A pair of pulsed fiber lasers, preferably single-frequency, generate output pulses at frequencies ?1 and ?2 that overlap temporally. A beam combiner combines the laser outputs and routes the combined output to a GHz generator head where a nonlinear interaction process in the NLO material generates GHz radiation.

Abstract: A phosphate glass 1-?m fiber ASE source provides high power and broadband emission that covers wavelengths on the short side of Yb-doped silica. A single-mode fiber formed from phosphate glass is doped with highly elevated concentrations of Yb dopants 0.5-30 wt. % and typically 2-10 wt. %, far higher than either silica or germano-silicate. The high concentration of Yb dopant absorbs the pump in a short length, typically 10-150 cm instead of tens of meters, to provide high saturated output power and a shifted emission spectrum. The excess power allows the fiber ASE source to be configured to provide the output powers, emission bandwidth and stability desired by many applications. Furthermore, the ASE can be configured to emit a nearly Gaussian spectral profile without sacrificing power or bandwidth.

Abstract: A 2-?m fiber Amplified Spontaneous Emission (ASE) source provides a wide emission bandwidth and improved spectral stability/purity for a given output power. The fiber ASE source is formed from a heavy metal oxide multicomponent glass selected from germanate, tellurite and bismuth oxides and doped with high concentrations, 0.5-15 wt. %, thulium oxides (Tm2O3) or 0.1-5 wt% holmium oxides (Ho2O3) or mixtures thereof. The high concentration of thulium dopants provide highly efficient pump absorption and high quantum efficiency. Co-doping of Tm and Ho can broaden the ASE spectrum.

Abstract: A heavy metal oxide glass selected from germanate, tellurite and bismuth oxide glasses provides a host for highly efficient Thulium doped 2 ?m oxide glass and fiber lasers. The concentration of Thulium ions is high enough that energy transferred by the phenomenon of cross-relaxation will enhance laser emission at 2 ?m and suppress emission at 1.5 ?m so that 2 ?m emission is dominant.

Abstract: A low-noise, high-gain optical image amplifier includes a multi-mode pump source that injects optical energy into an active fiber's inner cladding to excite the dopant ions in a 2-D array of doped cores and provide gain. The cores are arranged to sample and collect light from an image incident on one end of the fiber, amplify the light and output an amplified pixilated image at the other end of the fiber. The multi-core active fiber preserves the spatial pattern and spectrum of the incident image. The cores may be configured as single-mode cores to preserve phase information or multi-mode cores to scramble the phase information. It is often desirable for the gain to be approximately uniform across the 2-D array. This can be achieved by pumping uniformly doped cores into their respective saturation regions.

Abstract: A distributed fiber sensor based on spontaneous Brillouin scattering uses a single-frequency fiber laser as a source and a cw Brillouin fiber ring laser as an OLO to optically shift the frequency of the OLO to set the Brillouin/OLO beat frequency within the bandwidth of a conventional heterodyne receiver. The distributed fiber sensor is capable of real-time measurement of both temperature and strain.

Abstract: A single-frequency Brillouin fiber ring laser with extremely narrow linewidth comprises a single-frequency narrow-linewidth rapid-tunable pump laser, a temperature-controlled acoustically-damped package for Brillouin fiber ring laser cavity, and an auto-tracking feedback electronic loop with novel configuration for active stabilization. The Pound-Drever-Hall frequency-locking technique is employed to keep pump laser frequency in resonance with one of the Brillouin fiber ring cavity modes. Instead of changing cavity length of Brillouin fiber ring laser, the pump laser frequency is rapidly tuned in the auto-tracking feedback electronic loop. This enables extremely narrow linewidth radiation emitted from a Brillouin fiber ring laser without stretching the fiber ring.

Abstract: An all-fiber Q-switched laser includes a gain fiber spliced between narrowband and broadband fiber gratings that define a polarization-dependent resonant cavity. The narrowband grating is, for example, formed in a PM fiber to create a polarization-dependent reflection band. A modulator applies stress to the fiber chain to induce birefringence and switch the cavity Q-factor to alternately store energy in the gain fiber and then release the energy in a laser pulse.

Abstract: A compact single frequency, single-mode 2 ?m fiber laser with narrow linewidth, <100 kHz and preferably <100 kHz, is formed with a low phonon energy glass doped with triply ionized rare-earth thulium and/or holmium oxide and fiber gratings formed in sections of passive silica fiber and fused thereto. Formation of the gratings in passive silica fiber both facilitates splicing to other optical components and reduces noise thus improving linewidth. An increased doping concentration of 0.5 to 15 wt. % for thulium, holmium or mixtures thereof produces adequate gain, hence output power levels for fiber lengths less than 5 cm and preferably less than 3 cm to enable single-frequency operation.

Abstract: A fiber-laser-based implementation of a Terahertz source through difference frequency generation (DFG) by nonlinear optical (NLO) crystals is compact, tunable and scalable. A pair of fiber lasers (Q-switched, CW or mode-locked) generate single-frequency outputs at frequencies ?1 and ?2. A fiber beam combiner combines the laser outputs and routes the combined output to a THz generator head where a nonlinear interaction process in the NLO crystal generates THz radiation.

Abstract: A compact single frequency, single-mode 1 ?m fiber laser with narrow linewidth (<10 kHz) and high output power (>2 mW) is formed with an oxide-based multi-component glass fiber doped with triply ionized rare-earth ytterbium ions and fiber gratings formed in sections of passive silica fiber and fused thereto. The multi-component glass supports higher doping concentrations than standard silica fiber, hence higher output power levels in short cavities. Formation of the gratings in passive silica fiber both facilitates splicing to other optical components and reduces noise thus improving linewidth.

Abstract: A short laser cavity (up to 30 cm in length) comprising a free-space tunable MEMS Fabry-Perot filter, a collimating lens and a section of erbium-doped phosphate gain fiber (2-25 cm) is formed between a pair of broadband reflectors. The cavity is optically pumped to excite the erbium ions and provide gain, which establishes an initial longitudinal mode structure that spans the C-band with a mode spacing of at least 0.3 GHz and a roundtrip unsaturated gain of at least 8 dB over the tuning range. A controller tunes the MEMS filter, which has a filter function whose spectral width is at most ten and preferably less than four times the longitudinal mode spacing, to align its transmission maxima to one of a plurality of discrete output wavelengths that span the C-band. A thermal control element adjusts the longitudinal mode structure to align a single mode with the transmission maxima of the filter.

Abstract: A narrow-linewidth high-power single-frequency laser is realized by pumping a laser cavity with a pair of polarized single-mode pump lasers that are driven below their respective “micro-kink” regions and combined with a polarized beam combiner. The pump lasers emit at the same wavelength and include a length of polarization-maintaining (PM) fiber to maintain the polarization of the respective pumps. The laser cavity is selected from microchip, fiber and waveguide devices and is provided with optical feedback. This laser is capable of producing a stable high-power single-mode signal with a very narrow linewidth, e.g. less than 10 kHz and preferably less than 3 kHz.

Abstract: Thermally dissimilar glass fibers are fusion spliced by pretreating the cleaved end surface of the high-temperature fiber to provide a smooth surface for making good contact with the low-temperature fiber. The fibers are heated to a temperature that is high enough to soften the low-temperature fiber but not the high-temperature fiber and brought in contact to form the fusion joint.