Abstract: A device and method for compensating for chromatic dispersion in an optical signal. The optical signal is coupled between an optical waveguide of a type having (i) a fundamental-mode waveguide and (ii) a higher-order mode waveguide surrounding the fundamental-mode waveguide, wherein different effective indexes of refraction are associated with the fundamental-mode and higher-order mode waveguides. The device comprises a transmissive, long-period optical grating disposed along a length of the optical waveguide and has a receiving end and a transmitting end. The grating is chirped between the ends along a light conducting axis of the optical waveguide such that different wavelengths of the optical signal are coupled to the fundamental-mode and higher order mode waveguides at different points along the length of the grating so that chromatic dispersion is corrected at the transmitting end.

Abstract: An optical filter including at least one substrate and first and second thin-film interference filters disposed directly on the substrate. The interference filters include a plurality of hard coating thin film layers of alternating high and low index of refraction. A fluorescence spectroscopy system and method of selecting a band of wavelengths from light in a fluorescence spectroscopy system are also provided.

Abstract: Thin-film interference filters are constructed with a generalized pattern of layers differing in both thickness and refractive index to produce spectral responses appropriate for adjusting optical power among a plurality of different wavelength channels. Each of the layers is composed of unit sub-layers having thicknesses equal to a quarter-wavelength thickness of a monitoring beam. Interference fluctuations of the monitoring beam associated with the deposition of the unit sub-layers enable a gain-flattening filter to achieve greater manufacturing accuracy by exploiting self-correcting effects of “turning point monitoring” techniques.

Abstract: An optical recording material which when exposed to actinic radiation produces a change in optical properties in the exposed regions, thereby providing a pattern of intelligence for storing and retrieving information, the recording material comprising: a) a binder; b) a reactant which is capable of undergoing a chemical transformation upon a one electron oxidation, thus causing the change in optical properties in the exposed regions; and c) a sensitizer capable of absorbing actinic radiation to cause an initial one electron oxidation of the reactant.

Abstract: An optical recording material which when exposed to actinic radiation produces a change in optical properties in the exposed regions, thereby providing a pattern of intelligence for storing and retrieving information, the recording material comprising:

Abstract: A device and method for compensating for chromatic dispersion in an optical signal. The optical signal is coupled between an optical waveguide of a type having (i) a fundamental-mode waveguide and (ii) a higher-order mode waveguide surrounding the fundamental-mode waveguide, wherein different effective indexes of refraction are associated with the fundamental-mode and higher-order mode waveguides. The device comprises a transmissive, long-period optical grating disposed along a length of the optical waveguide and has a receiving end and a transmitting end. The grating is chirped between the ends along a light conducting axis of the optical waveguide such that different wavelengths of the optical signal are coupled to the fundamental-mode and higher order mode waveguides at different points along the length of the grating so that chromatic dispersion is corrected at the transmitting end.

Abstract: Long-period gratings are written more quickly and at higher intensities by amplitude masks having shadow-forming patterns that scatter, redirect, or otherwise divert shadow portions of radiation used for writing the gratings instead of blocking the shadow portions by absorption or reflection. The shadow-forming masks can be formed along transparent base optics by arrays of diffusers, diffractors, or refractors that relatively divert different portions of the radiation.

Abstract: A single-mode fiber includes a grating located near a fiber tip to shift transmitted light from a fundamental core mode to one or more higher cladding modes. Light exiting the fiber from the cladding mode occupies more area but is more collimated. Translational alignment tolerances are relaxed by the improvement in collimation, allowing couplings to be made directly with the single-mode fiber or through the intermediacy of a conventional lens, which can itself be aligned more readily and be less fast.

Abstract: A method/system are provided for measuring the N×N scalar transfer function elements for an N-port guided wave device. Optical energy of a selected wavelength is generated at a source and directed along N reference optical paths having N reference path lengths. Each reference optical path terminates in one of N detectors such that N reference signals are produced at the N detectors. The reference signals are indicative of amplitude, phase and frequency of the optical energy carried along the N reference optical paths. The optical energy from the source is also directed to the N-ports of the guided wave device and then on to each of the N detectors such that N measurement optical paths are defined between the source and each of the N detectors. A portion of the optical energy is modified in terms of at least one of the amplitude and phase to produce N modified signals at each of the N detectors.

Abstract: Polarization monitoring and control in a lightwave communication system is achieved by using an in-line polarimeter in conjunction with a polarization controller. The devices are readily compact, accurate and therefore capable of implementation in a variety of system applications. In one embodiment, a polarimeter and controller can be coupled together by a feedback loop between the polarimeter output and the controller input to provide “active polarization control” (APC).

Abstract: An in-line optical fiber polarimeter comprises a plurality of fiber gratings and a single wave plate, disposed sequentially along a length of optical fiber. The fiber gratings are precisely oriented and have a predetermined grating period such that each grating functions to out-couple a predetermined portion of the optical signal passing through the polarimeter. A separate detector is associated with each grating to measure the out-coupled signal. The four Stokes parameters can be determined from the set of measurements and then used to determine to state of polarization of an optical signal passing through the polarimeter.

Abstract: Stability of a pump laser for activating an erbium amplifier is enhanced by a grating which results in laser operation in the coherence collapse regime.

Abstract: An optical transmission system having a transmission waveguide, an optical amplifier, a pump radiation source for supplying pump radiation to the optical amplifier, and a Bragg grating for reflecting pump radiation to the amplifier. The Bragg grating is produced using two collimated, non-collinear beams of actinic radiation to form an interference pattern in a medium. While changing the product .lambda..times.0.5 csc .phi./2, the interference pattern is advanced relative to the medium such that the interference pattern has a spatially varying period. The resulting Bragg grating has a sufficiently wide bandwidth in reflection, sufficiently high extinction in transmission, and sufficiently low intrinsic loss that the pump radiation source may be located at least one kilometer from the optical amplifier.

Abstract: An improved Bragg grating for an optical waveguide comprising a core and a cladding. The grating includes refractive index perturbations formed within the waveguide. It has a bandwidth in reflection having a full width at half-maximum greater than 12 nm, a total intrinsic optical loss less than 0.2 dB, and a total peak optical extinction, measured in transmission, greater than 20 dB.

Abstract: The present invention is predicated upon the discovery by applicants of a relationship describing thermal decay of radiation-induced index changes and a mechanism which permits stabilization by accelerated aging. Specifically, the induced index change decays in proportion to 1/(1+At.sup..alpha.) where A and .alpha. are functions of temperature, and the decay can be accelerated by heat treatment. As a consequence, the extent of decay can be determined for arbitrary time and temperature and, significantly, an appropriate heat treatment can be scheduled for making a device stable within predeterminable limits.

Abstract: Stability of a pump laser for activating an erbium amplifier is enhanced by a grating which results in laser operation in the coherence collapse regime.

Abstract: A method is described for selectively modifying the refractive index of an optically transmissive body having an optical propagation axis. According to this method, polarized, actinic radiation is impinged on at least a portion of the body. In contrast to methods of the prior art, the actinic radiation is at least 60% polarized with a polarization direction parallel to a plane containing the propagation axis.

Abstract: The invention involves a method for making Bragg gratings in glass optical fibers, or other glass optical waveguides, which is relatively insensitive to perturbations in the actinic light used for processing. This method is suitable for mass production and lends itself well to the manufacturing environment. The invention method involves first providing an optical phase grating. An interference pattern is generated by impinging a single light beam on the grating. The optical waveguide to be processed is exposed to this interference pattern, leading to the formation of a Bragg grating in the waveguide.