Abstract: A system testing the speed of a microwave photonic system, having a Mach Zehnder interferometer that includes a first arm with a photonic system to be tested and an amplifier arranged to amplify the output of the photonic system, and a second arm with an attenuator configured to match the output power of the amplifier, with at least one filter arranged at the output of the Mach Zehnder interferometer, the filter having a pass band that includes the center frequency of a continuous wave microwave signal applied to the Mach Zehnder interferometer arms. A continuous wave microwave signal is applied to the input of the Mach Zehnder interferometer, a signal is applied to only the second arm with the photonic link, and the output of the bandpass filter is measured with an oscilloscope and a microwave power detector.

Abstract: A true time delay system for optical signals includes a hollow core optical waveguide, a droplet of reflective liquid metal disposed in the hollow core, and an actuator coupled to a first end of the waveguide to move the droplet longitudinally within the hollow core. In one example, the waveguide is a hollow core photonic bandgap fiber. In one example, the actuator is a pressure actuator that introduces or removes gas into the core. Light enters the optical fiber, is transmitted through the fiber toward the reflective surface of the droplet, and is reflected back through the fiber and exits at the same end of the photonic bandgap optical fiber that it entered. The fiber optic device can provide a continuously-variable optical path length of over 3.6 meters (corresponding to a continuously-variable true-time delay of over 12 ns, or 120 periods at a 10 GHz modulation frequency), with negligible wavelength dependence across the C and L bands.

Abstract: A system testing the speed of a microwave photonic system, having a Mach Zehnder interferometer that includes a first arm with a photonic system to be tested and an amplifier arranged to amplify the output of the photonic system, and a second arm with an attenuator configured to match the output power of the amplifier, with at least one filter arranged at the output of the Mach Zehnder interferometer, the filter having a pass band that includes the center frequency of a continuous wave microwave signal applied to the Mach Zehnder interferometer arms. A continuous wave microwave signal is applied to the input of the Mach Zehnder interferometer, a signal is applied to only the second arm with the photonic link, and the output of the bandpass filter is measured with an oscilloscope and a microwave power detector.

Abstract: A true time delay system and method for an optical carrier signal modulated with a microwave signal. The system includes a beam deflector, with the optical signal being imaged onto the beam deflector, a stationary reflective diffractive grating arranged in a Littrow configuration, a focusing element arranged between the beam deflector and the stationary reflective diffractive grating. In operation, the beam deflector steers the optical beam across the clear aperture of the focusing element and the focusing element transmits the steered beam to the reflective diffractive grating. A change in optical path length experienced by the optical beam as the beam is scanned across the grating surface results in a relative phase delay in the optical beam. The beam deflector can be a rotating mirror, an acousto-optic beam deflector, or an electro-optic beam deflector. The focusing element can be a lens or a curved mirror.

Abstract: A true time delay system for optical signals includes a hollow core optical waveguide, a droplet of reflective liquid metal disposed in the hollow core, and an actuator coupled to a first end of the waveguide to move the droplet longitudinally within the hollow core. In one example, the waveguide is a hollow core photonic bandgap fiber. In one example, the actuator is a pressure actuator that introduces or removes gas into the core. Light enters the optical fiber, is transmitted through the fiber toward the reflective surface of the droplet, and is reflected back through the fiber and exits at the same end of the photonic bandgap optical fiber that it entered. The fiber optic device can provide a continuously-variable optical path length of over 3.6 meters (corresponding to a continuously-variable true-time delay of over 12 ns, or 120 periods at a 10 GHz modulation frequency), with negligible wavelength dependence across the C and L bands.

Abstract: An apparatus for creating sheathed flow includes an inlet section comprising an array of tubes including at least one sheath inlet port and a sample inlet port, a flow focusing section downstream from the inlet section, an optical access section downstream from the flow focusing region and comprising opposing flat surfaces, and an outlet section downstream from the optical access section, wherein the apparatus is operable to create a sheathed flow around a fluid introduced into the sample inlet port and to maintain the sheathed flow through the optical access section. Applications of the apparatus and method include bead/particle counting, flow cytometry, waveguiding, and fluid control.

Abstract: The application of an optical beam redirects sheathed micro-fluidic flow without direct interaction with the sample. The hydrodynamic properties of the sheath are locally modified due to optical absorption and heating, resulting in a spatial shift of the sample flow. The technique can result in up to 100 ?m shift at peak flow velocities of 19 mm/sec.

Abstract: A true time delay system and method for an optical carrier signal modulated with a microwave signal. The system includes a beam deflector, with the optical signal being imaged onto the beam deflector, a stationary reflective diffractive grating arranged in a Littrow configuration, a focusing element arranged between the beam deflector and the stationary reflective diffractive grating. In operation, the beam deflector steers the optical beam across the clear aperture of the focusing element and the focusing element transmits the steered beam to the reflective diffractive grating. A change in optical path length experienced by the optical beam as the beam is scanned across the grating surface results in a relative phase delay in the optical beam. The beam deflector can be a rotating mirror, an acousto-optic beam deflector, or an electro-optic beam deflector. The focusing element can be a lens or a curved mirror.

Abstract: The application of an optical beam redirects sheathed micro-fluidic flow without direct interaction with the sample. The hydrodynamic properties of the sheath are locally modified due to optical absorption and heating, resulting in a spatial shift of the sample flow. The technique can result in up to 100 ?m shift at peak flow velocities of 19 mm/sec.

Abstract: An apparatus for creating sheathed flow includes an inlet section comprising an array of tubes including at least one sheath inlet port and a sample inlet port, a flow focusing section downstream from the inlet section, an optical access section downstream from the flow focusing region and comprising opposing flat surfaces, and an outlet section downstream from the optical access section, wherein the apparatus is operable to create a sheathed flow around a fluid introduced into the sample inlet port and to maintain the sheathed flow through the optical access section. Applications of the apparatus and method include bead/particle counting, flow cytometry, waveguiding, and fluid control.

Abstract: An optical receiver for receiving a signal from an optical fiber in a fiber-optic digital transmission system that includes a first low noise optical amplifier to amplify an input optical signal. The first low noise optical amplifier has an input 3 dB compression point lower than the desired system input sensitivity at a desired bit rate. A high power optical amplifier further amplifies the amplified optical signal, and has an automatic gain control for output signal leveling at a desired operation point of the transmission system. A high current photodetector converts the further amplified optical signal from the high power optical amplifier to an electrical signal that drives a retiming circuit without requiring further amplification of the electric signal.

Abstract: An optical waveguide-binding sensor which increases sensor sensitivity to fluorescence detection during assays of liquids based on adjustments in the V number along the optical waveguide. The sensing waveguide includes a mode converting section where the V number of the wavguide gradually increases from the distal sensing end of the mode converting section to the proximal end of the mode converting section. The gradually change in V number can be accomplished by either gradually inwardly tapering waveguide along the sensor portion from the proximal end, or by gradually varying the dopant concentration along the sensing portion. The sensor tapers in diameter to change the V number along the distal end of the optical waveguide.

Abstract: A method for correcting birefringence in a fiber optic coupler comprising measuring the intrinsic birefringent retardation, fast axis orientation and rotation of separate paths through the coupler and adding lumped birefringent elements to the ports of the coupler in a fashion to compensate for the intrinsic birefringence.

Abstract: A polarization-preserving single mode fiber coupler, fabricated by a method which does not require mutually aligning the fiber polarization axes provided the actual misalignment angle is not close to 90.degree.. The protective jackets from two or more polarization-preserving single mode birefringent fibers are partially removed and the fibers are twisted around each other to bring them into contact over the jacketless region and provide a coupling length that is large compared to the birefringent beat length of the fibers. Next, the cladding layers of the fibers in the contacting region are partially etched without degrading the birefringent beat length over their coupling length. Then, the etched region is heated to the softening point of the fibers while axial tension is applied to taper and fuse the etched region until a desired coupling of the fibers is achieved. Finally, a mechanical supporting structure is added to the tapered and fused region of the fibers.

Abstract: A method and means for forming an in-line integrated optical fiber polarizer comprising the steps of providing a length of highly birefringent optical fiber, and thermal tapering one or more separated but approximately adjacent small sections of that optical fiber in order to reduce the core diameter at those sections. This core diameter reduction adjusts the V-value for the fiber so that polarization-dependent transmission effects become evident at the wavelength of operation.

Abstract: An attachment tool and method for attaching a connector to a plastic-cove optic fiber, said connector formed with a bore slightly smaller than the covered fiber but slightly larger than the fiber core, the tool comprising a block of rigid material having a flat surface containing a straight groove running into and away from a central excision, the dimensions of the groove and excision being such that when the fiber is thread through the connector, and the connector is laid in the excision and the fiber in the groove, the fiber is substantially straight and centrally placed within the connector bore. A heater is used to heat the connector and soften the covering so that the fiber can be pulled through the bore by extrusion of the covering. The covering, which now fills the bore around the fiber core, is allowed to cool and harden, and the protruding fiber is cut off flush with the end of the connector.

Abstract: Optical access and duplex couplers for multimode, fiber, data transmission ines. Access couplers are for use with multiterminal communication systems whereas duplex couplers allow a single fiber to be used for data transmission in both directions. Grooves of different depths and widths are etched into silicon along natural crystal planes to position fibers of different diameters and to provide reflective silvered surfaces. Optical communication signals pass through smaller-diameter transmission lines to larger lines. Light surrounding the smaller-diameter line from the larger line is reflected by the reflective surfaces. Thus, information may be received and added as desired.

Abstract: A bidirectional optical communication system which includes a transmission ine which directs radiation onto a reflective surface through which a smaller-diameter fiber is inserted. The smaller-diameter fiber directs radiation into the larger-diameter fiber for transmission away from the reflective surface simultaneous with radiation transmitted through the larger-diameter fiber toward the reflective surface. A reflective surface and small fiber may be at each end of the larger-diameter fiber for bidirectional operation.

Abstract: An interferometric fiber optic sensor and method are provided for controlling the optical phase of a fiber interferometer by an optically induced change in the refractive index for one arm of the fiber interferometer and providing a passive all-optical phase shift interrogation in response to this dependency on the optically induced change in the refractive index.