Abstract: An apparatus includes a laser source configured to output laser light at a target frequency, and a measurement unit configured to measure a deviation between an actual frequency outputted by the laser source at a current period of time and the target frequency of the laser source. The apparatus includes a feedback control unit configured to, based on the measured deviation between the actual and target frequencies, control the laser source to maintain a constant frequency of laser output from the laser source so that the frequency of laser light transmitted from the laser source is adjusted to the target frequency. The feedback control unit can control the laser source to maintain a linear rate of change in the frequency of its laser light output, and compensate for characteristics of the measurement unit utilized for frequency measurement. A method is provided for performing the feedback control of the laser source.

Abstract: An apparatus includes a laser source configured to output laser light at a target frequency, and a measurement unit configured to measure a deviation between an actual frequency outputted by the laser source at a current period of time and the target frequency of the laser source. The apparatus includes a feedback control unit configured to, based on the measured deviation between the actual and target frequencies, control the laser source to maintain a constant frequency of laser output from the laser source so that the frequency of laser light transmitted from the laser source is adjusted to the target frequency. The feedback control unit can control the laser source to maintain a linear rate of change in the frequency of its laser light output, and compensate for characteristics of the measurement unit utilized for frequency measurement. A method is provided for performing the feedback control of the laser source.

Abstract: An apparatus includes a laser source configured to output laser light at a target frequency, and a measurement unit configured to measure a deviation between an actual frequency outputted by the laser source at a current period of time and the target frequency of the laser source. The apparatus includes a feedback control unit configured to, based on the measured deviation between the actual and target frequencies, control the laser source to maintain a constant frequency of laser output from the laser source so that the frequency of laser light transmitted from the laser source is adjusted to the target frequency. The feedback control unit can control the laser source to maintain a linear rate of change in the frequency of its laser light output, and compensate for characteristics of the measurement unit utilized for frequency measurement. A method is provided for performing the feedback control of the laser source.

Abstract: An apparatus includes a laser source configured to output laser light at a target frequency, and a measurement unit configured to measure a deviation between an actual frequency outputted by the laser source at a current period of time and the target frequency of the laser source. The apparatus includes a feedback control unit configured to, based on the measured deviation between the actual and target frequencies, control the laser source to maintain a constant frequency of laser output from the laser source so that the frequency of laser light transmitted from the laser source is adjusted to the target frequency. The feedback control unit can control the laser source to maintain a linear rate of change in the frequency of its laser light output, and compensate for characteristics of the measurement unit utilized for frequency measurement. A method is provided for performing the feedback control of the laser source.

Abstract: The telephone handset for the infirm includes a housing, wherein the housing has the appearance of an old-style telephone handset, internal electronics including a microphone, a speaker, wireless communication circuitry, and signal processing circuitry for processing signals received by the wireless communications circuitry to drive the speaker and for processing signals received from the microphone to transmit a signal representative of the received microphone signal wireless to one or more remote audio communication devices. The telephone handset also includes a simplified user interface which includes a predetermined number of keys less than ten, where the keys are programmed to cause the internal electronics to initiate contact with at least one specific remote audio communication device upon actuation. The telephone handset also has a multifunction user interface with at least a full numeric keypad and other keys sufficient to program the keys of the simplified user interface.

Abstract: A single-ended long period grating optical device is presented. The single-ended optical device comprises an optical waveguide having at least one core mode and a plurality of cladding modes. At least one long period grating couples light from the core mode to the cladding modes. A reflector is positioned in an operable relationship to the long period grating, and the reflector reflects a signal. A mode stripper is positioned after the long period grating and removes the cladding modes from a transmitted signal and the reflected signal.

Abstract: Uniformity of optical coupling of optical elements such as couplers and splitters is improved by heat treatment which causes dopants in the core of an optical fiber to diffuse into material from the cladding layer of the optical fibers from which the optical element is formed, resulting in a substantially homogeneous interior region of the star coupler or splitter. Increased lossiness of the optical element thus formed may be limited by termination of the heat treatment before dopant diffusion reaches equilibrium throughout the fibers so that a portion of the cladding layer of the fibers remains surrounding the substantially homogeneous region where the fibers have been fused together. Dopant diffusion is constrained to a substantially radial direction in each fiber by uniformity of heating over a region where at least two fibers are twisted together.

Abstract: Uniformity of optical coupling of optical elements such as star couplers and splitters is improved by heat treatment which causes dopants in the core of an optical fiber to diffuse into material from the cladding layer of the optical fibers from which the optical element is formed, resulting in a substantially homogeneous interior region of the star coupler or splitter. Increased lossiness of the optical element thus formed may be limited by termination of the heat treatment before dopant diffusion reaches equilibrium throughout the fibers so that a portion of the cladding layer of the fibers remains surrounding the substantially homogeneous region where the fibers have been fused together.

Abstract: The fibers are bound together about 1 cm apart. An oxy-propane torch is used to heat the fibers so that they fuse together. At the same time, the two relatively movable translational stages to which the fibers are clamped are pulled apart to form a biconical tapered region in the fibers. The fibers are tapered until a desired coupling ratio is achieved. After the insertion loss is measured, the torch is reintroduced into the taper region and one side (e.g., the right side) of the taper region is rotated with a minimal increase in the taper length, i.e., the distance between the two stations is increased only enough to keep an even tension in the taper region.

Abstract: An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors.

Abstract: Tapered two-mode optic fibers are used as sensors with sensitivity varying as a function of length. The optical fiber sensors act as vibrational-mode filters thereby performing initial signal processing of the sensor signal. The sensors are based on the differential propagation constant in a two-mode fiber that is directly dependent on the normalized frequency or V-number. Tapering the fiber changes the V-number and hence can change the sensitivity of the sensor along its length. By choosing an appropriate weighting function in the manufacture of the sensor, it is possible to implement vibrational-mode analysis, vibrational-mode filtering and other functions that are critical in control system applications.

Abstract: Optic fiber coupler fabrication stations allow one-step packaging and reduce fabrication time. The optic fiber coupler fabrication stations produce a single piece construction of the coupler package with improved uniformity. Two linear translation stages are driven in opposing directions using left and right hand threaded rods connected to a common drive shaft driven by a small electric motor. Fibers to be coupled are clamped into the station to provide the necessary tension during the tapering process. The fibers are tied together using cotton thread, and an oxy-propane torch is used to fuse the fibers together while the two translation stages pull the fibers to form a biconical tapered region in the fibers.