Abstract: Bright entangled photon sources including an alignment-free, fiber-based, mechanically-rugged and generic interferometric module are disclosed. The inherent phase-stability of a Sagnac interferometer is deployed. High down-conversion efficiency of periodically poled nonlinear-waveguides is combined with the optical gain of semiconductor optical amplifiers and immunity of fiber optics. A single compact interferometric engine combines these attributes, allowing highly stable, integrable and bright polarization entangled-photon sources operating at room temperature. Using a minimum number of in-line optical parts, the compact module is based on a novel method that enhances the long-term stability and efficiency without compromising the entanglement quality. Besides energy entanglement, polarization entanglement is presented and set through the operational conditions. An optional periodically poled nonlinear waveguide can be hosted to achieve the desired spectral bandwidth and photons generation rate.

Abstract: There is provided a biofilm capacitance microbial electrochemical cell (MEC) sensor to measure organic carbon in water and wastewater rapidly and accurately, represented by the 5-day biochemical oxygen demand (BOD5). The MEC runs at charging (open circuit) and discharging (close circuit) conditions alternately to improve the sensitivity, response time and accuracy. The detectable BOD5 concentrations with the biofilm-capacitance MEC range from 5 to 250 mg/L (R2>0.9). The MEC sensor enables BOD5 measurements at every 2 minutes (1 minute charging and 1 minute discharging), indicating semi-continuous quantification of organic carbon in water and wastewater.

Abstract: There is provided a design of a device consisting of a patterned semiconductor material to provide enhanced detection bandwidth and efficiency of terahertz (THz) pulses with an electro-optic sampling. One device has a semiconductor crystal having a patterned grating on a surface of the semiconductor. In a system, there could optionally be a quarter-wave plate after the semiconductor crystal, followed by a prism. A pair of balanced photodiodes can optionally be provided after the prism. A pulse laser having a NIR beam and THz beam is sent through the semiconductor crystal to the quarter-wave plate to the prism to the photodiodes, wherein the patterned grating on the semiconductor crystal diffracts the NIR beam while the THz remains unaffected. The photodiodes can detect the result.

Abstract: This disclosure is directed at a method and device capable of producing polarization entangled photon pairs and accomplishing polarization insensitive wavelength conversion. The device includes a double displacement interferometer, the interferometer of which contains an input beam displacing section including a plurality of orthogonally oriented optical beam displacing elements; a wavelength conversion section including a plurality of orthogonally oriented non-linear optical wavelength converters; an output beam recombination section including a plurality of orthogonally oriented optical beam displacing elements.

Abstract: There is provided a system for measuring temperature and strain simultaneously utilizing Brillouin Scattering within an optical fiber. The system has a cladding, a first optical core within the cladding and a second optical core within the cladding and having a different refractive index profile and/or composition than the first core. Means to couple light into and out of said individual optical cores and/or from one optical core to the other within the fiber is provided along with means for calculating strain and temperature characteristics based on measured Brillouin frequencies for said optical cores.

Abstract: A device including an optical tap and waveguide in the core and cladding of an optical fiber together with a glass ferrule that is angle polished to provide a reflection surface (with or without total internal reflection) that produces a reflection of the light tapped from the optical fiber to reach the bottom of the glass ferrule and propagate in a direction that is perpendicular to (or at least different than the direction of propagation close to) the axis of the optical fiber. The fiber waveguide may be created using an ultrafast fabrication method and the glass ferrule can itself be modified by the same ultrafast laser technique to further manipulate the light traveling inside.

Abstract: There is provided a fiber-based broadband polarization-entangled photon source. The polarization entangled photon pair source module comprises an optical fiber, a pump to couple light into the fiber and one or more suppression filters following the fiber. The optical fiber preferably is a periodically poled silica fiber and the pump is preferably a laser diode pump. The present invention relates to a compensation-free, alignment-free, diode-pumped, broadband, polarization-entangled photon source that is based on a low-birefringence fiber. It has an extremely simple configuration capitalizing on the compensation-free and direct generation capability of a low-birefringence fiber. The source has broad bandwidth, high-quality and polarization-entanglement. The present invention is compact, robust, low-power, low-cost, alignment-free and room-temperature operable, featuring a simple turn-key, plug-and-play operation.

Abstract: There is provided a method to fabricate optical taps and waveguide devices in photonic crystal fibers and other fibers with hollow structures. The method involves a preparation step, where the hollow holes inside the fiber are collapsed or partially modified locally; and a waveguide fabrication step, where a femtosecond laser is focused inside the fiber and used to produce optical waveguides that interact in the region that was previously modified in the preparation step.

Abstract: The present invention presents a flexible, stepped frequency, radar based, imaging inspection system. The imaging inspection system can be used in airports, seaport sites, borders, postal processing centres, and sensitive sites. It comprises a millimetre-wave Stepped Frequency Continuous Wave (SFCW) radar module (2) connected to a transmitting channel and a receiving channel. The transmitting channel may comprise a frequency upconvertor (8) and the receiving channel may comprise a frequency downconvertor (10). A digital signal processing unit (14) reconstructs a conductivity profile and a permittivity profile of an object under test (OUT) from measurement data collected via a phase-array antenna or a translational stage (18) based on synthetic aperture focusing (SAF).

Abstract: There is provided a system for measuring temperature and strain simultaneously utilizing Brillouin Scattering within an optical fiber. The system has a cladding, a first optical core within the cladding and a second optical core within the cladding and having a different refractive index profile and/or composition than the first core. Means to couple light into and out of said individual optical cores and/or from one optical core to the other within the fiber is provided along with means for calculating strain and temperature characteristics based on measured Brillouin frequencies for said optical cores.

Abstract: There is provided a system for measuring temperature and strain simultaneously utilizing Brillouin Scattering within an optical fiber. The system has a cladding, a first optical core within the cladding and a second optical core within the cladding and having a different refractive index profile and/or composition than the first core. Means to couple light into and out of said individual optical cores and/or from one optical core to the other within the fiber is provided along with means for calculating strain and temperature characteristics based on measured Brillouin frequencies for said optical cores.

Abstract: The present invention is directed to the creation of optical waveguiding devices from standard optical fibers by the creation of zones of permanently altered refractive index characteristics therein. A high intensity femtosecond laser beam is focused at a predetermined target region in the fiber so as to soften the glass material at the target region. After aligning the focal region with the target region in the fiber there will be relative movement between the focal region and the fiber, which has the effect of sweeping the focal region across the fiber in a predetermined path, so as to create a secondary waveguide path. A portion of the light traveling along the core is removed from the core along the secondary waveguide path such that the device can be utilized as an attenuator, an optical tap, or a polarimeter.

Abstract: The present invention is directed to the creation of optical waveguiding devices from standard optical fibers by the creation of zones of permanently altered refractive index characteristics therein. A high intensity femtosecond laser beam is focused at a predetermined target region in the fiber so as to soften the glass material at the target region. After aligning the focal region with the target region in the fiber there will be relative movement between the focal region and the fiber, which has the effect of sweeping the focal region across the fiber in a predetermined path, so as to create a secondary waveguide path. A portion of the light traveling along the core is removed from the core along the secondary waveguide path such that the device can be utilized as an attenuator, an optical tap, or a polarimeter.

Abstract: A method and system for simultaneously measuring strain and temperature characteristics of an object involves the attachment to the object of a pair of optical fibers having different refractive indices, the fibers being connected together at least one end thereof, and directing laser light into at least one end of the fibers. The Brillouin frequency of each of the fibers is measure and the strain and temperature characteristics are calculated based on the coefficients of strain and temperature and the measured Brillouin frequencies of the fibers.

Abstract: An adjustable focus connector with spring action is especially adapted for use with common FC or SAM fiber optic receptacles. The connector includes a ferrule holder which mounts a fiber-carrying ferrule at a distal end thereof. At its proximal end the ferrule holder is threadedly connected to a lead screw member. A thrust collar surrounds the ferrule holder and traps a compression spring in the cavity between the thrust collar and the ferrule holder. Because of appropriate interengagement between the components the ferrule holder cannot rotate relative to the trust collar. A traveler is threadedly connected to the lead screw and abuts against the thrust collar. A connection nut is provided at the distal end of the connector to connect it to the fiber optic receptacle. The spring action of the connector prevents damage to the fiber end during connection of the connector to the fiber optic receptacle.

Abstract: The present invention is directed to the creation of optical waveguiding devices from standard optical fibers by the creation of zones of permanently altered refractive index characteristics therein. A high intensity femtosecond laser beam is focused at a predetermined target region in the fiber so as to soften the glass material at the target region. After aligning the focal region with the target region in the fiber there will be relative movement between the focal region and the fiber, which has the effect of sweeping the focal region across the fiber in a predetermined path, so as to create a secondary waveguide path. A portion of the light traveling along the core is removed from the core along the secondary waveguide path such that the device can be utilized as an attenuator, an optical tap, or a polarimeter.

Abstract: The present invention is directed to the creation of optical waveguiding devices from standard optical fibers by the creation of zones of permanently altered refractive index characteristics therein. A high intensity femtosecond laser beam is focused at a predetermined target region in the fiber so as to soften the glass material at the target region. After aligning the focal region with the target region in the fiber there will be relative movement between the focal region and the fiber, which has the effect of sweeping the focal region across the fiber in a predetermined path. The result is a zone within the fiber in which the refractive index characteristics of the fiber have been permanently altered so as to control amplitude, phase, spatial propagation or polarization states of light within the material.

Abstract: A system and method for controlling an optical light source is provided. A current source drives the light source, while the voltage across and the current through the light source is measured. The voltage and current are converted to digital signals and sent to a neural network, which generates a modeled optical output power of the light source and a modeled value of the optical wavelength. A control circuit receives the modeled optical output power and wavelength and sends a control signal to the current source to minimize the difference between the desired power output and the modeled output power. In addition, a control signal is sent to a Peltier driver to control the temperature of a Peltier cooler in order to increase or decrease the wavelength emitted by a laser diode.