Abstract: The present application relates to radio detection and ranging (radar) systems and, in particular, to a radar system having a photonics-based signal generator. Such a radar system comprises a stepped-frequency optical signal generator, an optical-to-electrical converter, and a transmitter. The stepped-frequency optical signal generator is configured for converting an optical signal into a stepped-frequency optical signal. The optical-to-electrical converter for converting the stepped-frequency optical signal into a stepped-frequency electrical signal. The transmitter for transmitting a microwave signal based on the stepped-frequency electrical signal.

Abstract: Disclosed is a multi-channel power controller. The multi-channel power controller comprises a processing system configured to generate one or more control signals, and one or more extender modules operatively coupled to the processing system. The one or more 5 extender modules are configured to receive an input electrical power. Each extender module of the one or more extender modules is configured to receive a control signal of the one or more control signals, receive a portion of the input electrical power, and generate a plurality of output electrical powers using the received control signal and the portion of the input electrical power. Also disclosed is a power control system.

Abstract: This invention concerns real-time multi-impairment signal performance monitoring. In particular it concerns an optical device, for instance a monolithic integrated photonics chip, comprising a waveguide having an input region to receive a signal for characterization, and a narrow band CW laser signal. A non-linear waveguide region to mix the two received signals. More than one output region, each equipped with bandpass filters that extract respective discrete frequency bands of the RF spectrum of the mixed signals. And, also comprising (slow) power detectors to output the extracted discrete frequency banded signals.

Abstract: A method and apparatus for providing optical supercontinuum. The method comprises creating a spectrally narrow phase feature within a supercontinuum spectrum produced from a laser pulse that has been subjected to supercontinuum generation, thereby producing a modified supercontinuum spectrum, and propagating the modified supercontinuum spectrum through an optical waveguide that is suitable for supercontinuum generation, thereby further modifying the modified supercontinuum spectrum. The method may include modifying the modified supercontinuum spectrum by increasing its energy in a vicinity of the phase feature.

Abstract: An optical noise monitoring method and monitor, the monitor comprising an optical transmitter for receiving at least a portion of an optical signal, a device arranged to extract a reflected optical signal comprising a portion of the optical signal back-reflected by stimulated Brillouin scattering in the optical transmitter, and a photodetector for receiving the reflected optical signal. The optical transmitter can scatter the optical signal by stimulated Brillouin scattering.

Abstract: This invention concerns real-time multi-impairment signal performance monitoring, [n particular it concerns an optical device, for instance a monolithic integrated photonics chip, comprising a waveguide having an input region to receive a signal for characterization, and a narrow band CW laser signal. A non-linear waveguide region to mix the two received signals. More than one output region, each equipped with bandpass filters that extract respective discrete frequency bands of the RF spectrum of the mixed signals. And, also comprising (slow) power detectors to output the extracted discrete frequency banded signals.

Abstract: An optical noise monitoring method and monitor, the monitor comprising an optical transmitter for receiving at least a portion of an optical signal, a device arranged to extract a reflected optical signal comprising a portion of the optical signal back-reflected by stimulated Brillouin scattering in the optical transmitter, and a photodetector for receiving the reflected optical signal. The optical transmitter can scatter the optical signal by stimulated Brillouin scattering.

Abstract: A method and apparatus for providing optical supercontinuum. The method comprises creating a spectrally narrow phase feature within a supercontinuum spectrum produced from a laser pulse that has been subjected to supercontinuum generation, thereby producing a modified supercontinuum spectrum, and propagating the modified supercontinuum spectrum through an optical waveguide that is suitable for supercontinuum generation, thereby further modifying the modified supercontinuum spectrum. The method may include modifying the modified supercontinuum spectrum by increasing its energy in a vicinity of the phase feature.

Abstract: A tunable optical fiber device comprises a length of fiber having a core having a certain refractive index; a cladding peripherally surrounding the core with a refractive index less than the refractive index of the core; and at least one hollow region disposed within the cladding in proximity to the core or within the core itself. Fluid (typically liquid) controllably moved within the hollow region modifies the effective index of the fiber and thereby tunes its characteristics.

Abstract: In accordance with the invention, an optical fiber communication system is provided with a tunable linearly chirped Bragg grating in high birefringence fiber for reduction of polarization mode dispersion without increasing chromatic dispersion. A first embodiment using a single grating can be tuned for optimal PMD compensation, optimal chromatic compensation or optimal simultaneous compensation. Alternative embodiments using a plurality of gratings permit simultaneous compensation of both PMD and chromatic dispersion.

Abstract: In accordance with the invention, a modulated RZ pulse source comprises a modulated light source optically coupled to a stabilized Bragg grating filter and one or more optical taps. The light source is preferably modulated in power and frequency and has an adjustable channel wavelength ?. The Bragg grating filter has a reflectivity bandwidth having a high slope reflectivity cutoff and is preferably tunable. A feedback arrangement responsive to the taps keeps the source channel wavelength ? on the edge of the reflectivity bandwidth for shaping RZ pulses. When the Bragg grating is stabilized, the feedback system maintains ? at a value linked to the grating reflectivity edge and, by overlapping at least part of the optical spectrum of the source, converts the modulated source light into RZ pulses with high extinction ratio (?12 dB). The result is a high power, jitter-free RZ pulse source that is compact, inexpensive and power efficient.

Abstract: In accordance with the invention, an optical fiber communication system is provided with a tunable linearly chirped Bragg grating in high birefringence fiber for reduction of polarization mode dispersion without increasing chromatic dispersion. A first embodiment using a single grating can be tuned for optimal PMD compensation, optimal chromatic compensation or optimal simultaneous compensation. Alternative embodiments using a plurality of gratings permit simultaneous compensation of both PMD and chromatic dispersion.

Abstract: A multi-wavelength cascaded Raman resonator (“MWCRR”). The MWCRR has an optical source for pumping optical radiation centered around an input wavelength. The MWCRR further includes a Raman fiber having at least a first set of optical gratings for converting the pumped optical radiation to wavelengths other than the input wavelength. The Raman fiber also has at least one adjustable output coupler having a variable reflectivity for controlling the power of the optical radiation propagating from the at least one set of optical gratings at the wavelengths other than the input wavelength.

Abstract: Embodiments of the invention include an optical fiber device such as a tunable birefringent optical fiber having a core region, a cladding layer therearound, and a controllable active material disposed in, e.g., selective capillaries or pockets formed in the cladding layer. The active materials include, e.g., electro-optic material, magneto-optic material, photorefractive material, thermo-optic material and/or materials such as laser dyes that provide tunable gain or loss. The application of, e.g., temperature, light or an electric or magnetic field varies optical properties of the active material, which, in turn, varies or affects the propagation properties of optical signals in the device. The optical device can include a tapered region or long period grating that causes the core mode to spread or couple into the cladding region and, simultaneously, allows the active material to be relatively close to the propagated modes, thus allowing interaction between the active material and the propagating modes.

Abstract: A thermally tunable optical fiber device comprises a length of optical fiber including a device disposed within a microcapillary heater. The microcapillary heater can include a thin film resistive heater. The fiber itself can optionally include a thin film resistive heater overlying the device, and a plurality of nested microcapillary tubes can optionally provide a plurality of successive concentric heaters overlying the device. The heaters films can be films with uniform, tapered or periodically varying thickness. The heaters can be single layer or multiple layer. Multiple layer films can be superimposed with intervening insulating layers or plural layers can be formed on different angular regions of the microcapillary. Thus one can provide virtually any desired temperature versus length profile along the fiber device.

Abstract: The invention involves providing a microstructured fiber having a core region, a cladding region, and one or more axially oriented elements (e.g., capillary air holes) in the cladding region. A portion of the microstructured fiber is then treated, e.g., by heating and stretching the fiber, such that at least one feature of the fiber microstructure is modified along the propagation direction, e.g., the outer diameter of the fiber gets smaller, the axially oriented elements get smaller, or the axially oriented elements collapse. The treatment is selected to provide a resultant fiber length that exhibits particular properties, e.g., mode contraction leading to soliton generation, or mode expansion. Advantageously, the overall fiber length is designed to readily couple to a standard transmission fiber, i.e., the core sizes at the ends of the length are similar to a standard fiber, which allows efficient coupling of light into the microstructured fiber length.

Abstract: The invention involves providing a microstructured fiber having a core region, a cladding region, and one or more axially oriented elements (e.g., capillary air holes) in the cladding region. A portion of the microstructured fiber is then treated, e.g., by heating and stretching the fiber, such that at least one feature of the fiber microstructure is modified along the propagation direction, e.g., the outer diameter of the fiber gets smaller, the axially oriented elements get smaller, or the axially oriented elements collapse. The treatment is selected to provide a resultant fiber length that exhibits particular properties, e.g., mode contraction leading to soliton generation, or mode expansion. Advantageously, the overall fiber length is designed to readily couple to a standard transmission fiber, i.e., the core sizes at the ends of the length are similar to a standard fiber, which allows efficient coupling of light into the microstructured fiber length.

Abstract: Embodiments of the invention include an optical fiber device such as a tunable birefringent optical fiber having a core region, a cladding layer therearound, and a controllable active material disposed in, e.g., selective capillaries or pockets formed in the cladding layer. The active materials include, e.g., electro-optic material, magneto-optic material, photorefractive material, thermo-optic material and/or materials such as laser dyes that provide tunable gain or loss. The application of, e.g., temperature, light or an electric or magnetic field varies optical properties of the active material, which, in turn, varies or affects the propagation properties of optical signals in the device. The optical device can include a tapered region or long period grating that causes the core mode to spread or couple into the cladding region and, simultaneously, allows the active material to be relatively close to the propagated modes, thus allowing interaction between the active material and the propagating modes.

Abstract: A tunable optical fiber device comprises a length of fiber having a core having a certain refractive index; a cladding peripherally surrounding the core with a refractive index less than the refractive index of the core; and at least one hollow region disposed within the cladding in proximity to the core or within the core itself. Fluid (typically liquid) controllably moved within the hollow region modifies the effective index of the fiber and thereby tunes its characteristics.

Abstract: Embodiments of the invention include an optical fiber device such as a modulator, variable attenuator or tunable filter including an optical fiber having a core region, a cladding layer around the core region, and a controllable active material disposed in, e.g., capillaries or rings formed the cladding layer. The active materials include, e.g., electro-optic material, magneto-optic material, photorefractive material, thermo-optic material and/or materials such as laser dyes that provide tunable gain or loss. The application of, e.g., temperature, light or an electric or magnetic field varies optical properties of the active material, which, in turn, varies or affects the propagation properties of optical signals in the device. The optical device includes a tapered region that causes the core mode to spread into the cladding region and, simultaneously, allows the active material to be relatively close to the propagated modes, thus allowing interaction between the active material and the propagating modes.