Abstract: A single helix chiral fiber grating of a predetermined grating strength is provided that is operable to control light transmission in a predetermined wavelength range. The novel fiber grating comprises a first optical fiber with a first interface portion at a first end, a second interface portion at a second end, and a middle portion therebetween. The first optical fiber is configured with at least one fiber core, surrounded by a corresponding at least one cladding, with a first longitudinal section disposed within the first interface portion, a second longitudinal section disposed within the second interface portion, and also includes a longitudinal helical section, disposed therebetween within the middle portion, that comprises a longitudinal helix structure of a single predetermined handedness, having a predetermined pitch profile, and having a predetermined helix diameter profile selected and configured to produce the predetermined grating strength.

Abstract: A distributed elongated optical fiber detection system is provided, having at least one sensitive region, and being capable of detecting the occurrence and location(s) of one or more events along its length that cause one or more perturbations in the at least one sensitive region. In one embodiment of the invention, the novel detection system includes, at its first end, an optical signal source capable of launching a signal in a first signal mode through an optical fiber waveguide comprising at least one sensitive region along its length, and configured for transmitting at least two signal modes therethrough, toward its second end. A reflecting device, capable of reflecting only signals in a second signal mode, is positioned at the second end of the waveguide.

Abstract: An optical fiber mode coupling device, capable of being readily connected to a conventional optical fiber with a high degree of ruggedness, is provided. The inventive mode coupling device only allows transmission of at least one supported fiber mode therethrough, and is preferably configured to maximize the coupling, of at least one desired fiber mode, to the at least one supported fiber mode. Advantageously, the inventive mode coupling device is capable of performing the functions of a mode filter for the signal entering its first end, or serving as a mode conditioner for the signal entering its opposite second end.

Abstract: The present invention provides process for fabricating an optical fiber assembly that includes two or more integral optical fiber elements having different interface characteristics, where at least one of the elements is a fiber optic device (fiber grating, in-fiber polarizer, coupler, mode filter, etc.), and where the length, and thus the cost, of each fiber optic device is advantageously optimized. The inventive process utilizes a two-stage approach, where at a first process stage, one or more optical fibers are spliced to one or more predetermined optical fiber device preforms (usable to fabricate one or more optical fiber devices), and where at a second process stage, one or more preform processing techniques (such as one or more of: drawing, twisting, etching, wrapping, etc.), are applied to the one or more preforms, to fabricate one or more corresponding optical fiber devices that are already integral with the optical fibers on one or both ends, thus forming the desirable optical fiber assembly.

Abstract: An optical fiber coupler capable of providing a low loss, high coupling coefficient interface between conventional optical fibers and optical waveguide devices is provided. The novel coupler, which may be polarization maintaining, if a polarization maintaining preform is used in its fabrication includes a core, a cladding, a first end for interfacing with an optical fiber and a second end for interfacing with an optical waveguide device. The sizes of the core and cladding are gradually reduced from the first end to the second end in accordance with a predetermined reduction profile. Various parameters, such as refractive indices and sizes of the core and cladding and the reduction profile are selected to produce a low numerical aperture at the first end and a high numerical aperture at the second end, while advantageously minimizing insertion loss and maximizing the coupling coefficient at each end.

Abstract: An apparatus is disclosed for manufacturing chiral fibers having chiral fiber Bragg gratings properties from UV sensitive optical fibers, by using a UV laser beam to impose a chiral modulation of the refractive index at the core of the fiber.

Abstract: An optical fiber coupler capable of providing a low loss, high coupling coefficient interface between conventional optical fibers and optical waveguide devices is provided. The novel coupler, which may be polarization maintaining, if a polarization maintaining preform is used in its fabrication. includes a core, a cladding, a first end for interfacing with an optical fiber and a second end for interfacing with an optical waveguide device. The sizes of the core and cladding are gradually reduced from the first end to the second end in accordance with a predetermined reduction profile. Various parameters, such as refractive indices and sizes of the core and cladding and the reduction profile are selected to produce a low numerical aperture at the first end and a high numerical aperture at the second end, while advantageously minimizing insertion loss and maximizing the coupling coefficient at each end.

Abstract: An apparatus and method for fabricating fiber gratings from optical fibers by imposing constant or variable chiral refractive index modulation along an optical fiber. The refractive index modulation may be of single helix symmetry to produce a fiber grating enabling different propagation speed of signals with the same handedness as the structure with respect to signals with opposite handedness as the structure at a wavelength substantially equal to the pitch of the single helix, or of double helix symmetry to produce a chiral fiber Bragg grating. In several embodiments of the present invention the refractive index modulation is imposed by twisting and moving a specially prepared optical fiber through a heater that heats a small region of the fiber to a temperature sufficient to allow the fiber to twist in that region as it moves through the heater.

Abstract: An apparatus and method for manufacturing chiral fibers having chiral fiber Bragg gratings properties from UV sensitive optical fibers by using a UV laser beam to impose a chiral modulation of the refractive index at the core of the fiber.

Abstract: An x-ray detector includes a scintillator that converts an invisible-radiant-energy image into a visible-light image and a sensor array that converts the visible-light image into an electrical signal. The sensor array comprises a plurality of CMOS active pixel sensors.

Abstract: A method and apparatus for producing a X-ray image of a patient's teeth by placing an intra-oral sensor having a plurality of pixels disposed in a linear array inside the patient's mouth, and moving a radiation source around outside of the patient's mouth. The intra-oral sensor detects the radiation that has passed through the patient's teeth and generates corresponding output signals that depend on the amount of radiation arriving at each pixel. The information contained in the output signals is stored and can be used to create an X-ray image of the patient's teeth. The intra-oral sensor can be moved about inside the patient's mouth in coordination with the movement of the radiation source in order to improve the resulting image quality. This method and apparatus can be used to obtain an X-ray image of any number of teeth, including a panoramic image of all of the patient's teeth, in a single, quick, uninterrupted operation.

Abstract: An x-ray detector includes a scintillator that converts an invisible-radiant-energy image into a visible-light image and a sensor array that converts the visible-light image into an electrical signal. The sensor array comprises a plurality of CMOS active pixel sensors.

Abstract: AA method and apparatus for measuring bone density using x-ray radiation at two energy levels, and an image sensor array that comprises a plurality of CMOS active pixel sensors.

Abstract: A large area image detecting apparatus made by arranging a plurality of small area sensors in a stepped arrangement so that the inactive regions of the small sensors are covered by a active area of another small sensor. The apparatus may be used to detect light or radiation. A fiber optic assembly may be used to guide light from a flat scintillator plate onto the small sensors.