Abstract: A tunable filter may be utilized to successively tune to different wavelengths. As each wavelength of the wavelength division multiplexed signal is extracted, it may be successively power monitored. Thus, power monitoring may done without requiring separate power monitors for each channel. This results in considerable advantages in some embodiments, including reduced size, reduced complexities in fabrication, and reduced yield issues in some embodiments.

Abstract: A planar light wave circuit may have thin film filters integrated into the planar light circuit. Waveguides formed in the planar light wave circuit may convey light transmitted from and reflected by the thin film filters. A variety of optical devices may be formed with the hybrid technology.

Abstract: A method, apparatus, and system for monitoring optical signals in a planar lightwave circuit (“PLC”) by tapping light from an optical transmission medium (e.g., a waveguide or optical fiber), into which a grating has been written, out of a plane of the optical transmission medium and onto a photosensitive device are disclosed herein. In one embodiment, a tilted grating, with an angle greater than about 6 degrees from normal to a central axis of the optical transmission medium may be written into a waveguide in the PLC at a location at which an attribute (e.g., a wavelength or power) of an optical signal is to be measured. A portion of an optical signal may then be reflected out of a plane of the optical transmission medium, and be detected by a photodetector positioned in a second plane, distinct from the plane of the optical transmission medium.

Abstract: A method, apparatus, and system for monitoring optical signals in a planar lightwave circuit (“PLC”) by tapping light out of an optical transmission medium (e.g., a waveguide or optical fiber), into which a grating has been written, within a plane of the optical transmission medium and onto a photosensitive device are disclosed herein. In one embodiment, a tilted grating, with an angle greater than about 6 degrees from normal to a central axis of the optical transmission medium may be written into a waveguide in the PLC at a location at which an attribute (e.g., a wavelength or power) of an optical signal is to be measured. A portion of an optical signal may then be reflected out of a plane of the optical transmission medium, and be detected by a photodetector positioned in the plane of the optical transmission medium.

Abstract: A waveguide may be translated relative to the optical system that creates the grating in the waveguide. Phase errors that arise from the writing process may be corrected by appropriate translations of the waveguide relative to the system that creates the grating. In some embodiments, the waveguide may be translated relative to a phase mask used to write a grating into the waveguide.

Abstract: A plurality of channels of a wavelength division multiplexing system may be subjected to dispersion compensation in a fashion which enables tuning of the compensation for each individual wavelength channel. Moreover, the tuning may be done in a space-efficient fashion. The chirped Bragg gratings may be formed, for example, on a planar light circuit. Each grating may be heated to controllably adjust its dispersion compensation, in one embodiment of the present invention.

Abstract: A method, apparatus, and system for measuring optical phase and amplitude properties of an output optical field to characterize diffractive, refractive, and other optical elements to estimate, measure, and characterize an optical transfer function are disclosed herein. In a representative embodiment, a light source may generate an optical field incident to an optical element, such as a diffraction grating. An aperture plate may be positioned relative to the optical element to allow translation of at least one of the aperture plate or the optical element in a plane transverse to a surface normal of the optical element, resulting in an output optical field having spatially dependant amplitude and phase characteristics related to a position on the optical element and to the optical field incident to the optical element. The output optical field may then be detected and analyzed to characterize the optical transfer function of the optical element.

Abstract: Code-multiplexed communication systems, apparatus, and methods include coders that encode and decode data streams with synchronous, substantially orthogonal codes. Code-multiplexed communications systems encode data signals with such codes to control levels of decoding artifacts such as cross-talk at times or time intervals in which data is recovered. Some systems are based on synchronous, orthogonal codes that are obtained from complex orthogonal vectors. In an example, a three-level temporal-phase code that includes nine code chips and encodes and decodes data signals is a seven-channel communication system.

Abstract: The phase (and amplitude) of a wave front may be accurately measured using knowledge of the wave front of an optical field generated by an optical element, permitting the determination of the spatial transfer function of that optical element. As a device under test is scanned across an aperture plate having slits, variations in the relative amplitude and phase of light passing through the slits are affected by the optical properties of the device under test, in turn affecting the interference pattern at a detector. Changes in the amplitude and phase of the detected signal are directly and uniquely related to the transfer function of the device under test.

Abstract: An optical signal may be encrypted and decrypted using an encoder and a matched decoder. In this way, an encoded signal may be retrieved using a decoder that matches the encoder. The encoder may alter the phase or amplitude of the signal.

Abstract: Multiple Bragg gratings are fabricated in a single planar lightwave circuit platform. The gratings have nominally identical grating spacing but different center wavelengths, which are produced using controlled photolithographic processes and/or controlled doping to control the effective refractive index of the gratings. The gratings may be spaced closer together than the height of the UV light pattern used to write the gratings.

Abstract: In accordance with some embodiments of the present invention, while a Bragg grating is being written in a substrate, measurements may be taken to allow changes to be made in the writing process to reduce errors that may occur in the written grating. In one embodiment, multiple scans of the writing beam can be used. After a scan, measurements of the characteristics of the grating being written can be taken and corrections may be implemented on subsequent scans.

Abstract: A system for fabricating Bragg gratings includes an optical waveguide (e.g., an optical fiber, a planar waveguide), an interference pattern generator (e.g., a transmission phase grating such as a phase mask or a diffraction grating), first motion equipment (e.g. a nanostage), a pulsed light source (e.g. an excimer laser), and second motion equipment (e.g. a stepper motor). A method for fabricating Bragg gratings using this system includes providing relative motion between the optical waveguide and the interference pattern using the nanostage, providing relative motion in discrete increments between the pulsed light source and the assemblage comprising the optical waveguide, nanostage, and interference pattern generator using the stepper motor, and successively exposing the optical waveguide to the pulsed light through the interference pattern generator when the optical waveguide and interference pattern are effectively stationary relative to the pulsed light.

Abstract: Programmable waveguide coders are disclosed that include one or more corrugation segments and one or more spacer segments formed on or in a waveguide defined by a core in an electro-optic substrate. Each of the corrugation segments and the spacer segments are independently controllable with voltages applied to each segment's electrodes. The spacer segments permit application of a phase modulation to an input while the corrugation segments act as tunable gratings, wherein a center grating wavelength is tunable by applying a voltage to an electrode associated with the corrugation segment. In some embodiments, coders include only corrugation segments or only spacer segments. Such coders can be strain tuned or thermally tuned. The coders can be programmatically tuned to code or decode a time-wavelength code or other code.

Abstract: A mounting platform provides support and packaging for one or more fiber Bragg gratings and electronic circuitry (e.g., heaters, coolers, piezoelectric strain providers, temperature and strain sensors, feedback circuitry, control loops), which may be printed on or on the mounting platform, embedded in the mounting platform, or may be an “off-board” chip solution (e.g., the electronic circuitry may be attached to the mounting platform, but not formed on or defined on the mounting platform). The fiber Bragg gratings are held in close proximity to the electronic circuitry, which applies local and global temperature and/or strain variations to the fiber Bragg gratings to, for example, stabilize and/or tune spectral properties of the fiber Bragg gratings so that spatial variations in the fiber Bragg gratings that result from processing and manufacturing fluctuations and tolerances can be compensated for.

Abstract: A waveguide that is operative to produce a reflected optical signal having a spectral profile corresponding to a product of a spectral profile of an input optical signal and a predetermined complex-valued spectral filtering function wherein the waveguide includes a plurality of spatially distinct subgratings each possessing a periodic array of diffraction elements. The subgratings are situated and configured based on the predetermined complex-valued spectral filtering function.

Abstract: Encoders and decoders for applying composite codes to optical data signals include encoders and decoders for applying both subcodes and supercodes. The subcodes have a duration selected as less than or equal to an interchip duration or a chip duration of the supercodes. The encoders and decoders (“coders”) include fiber Bragg gratings configured to encode or decode a subcode, a supercode, or a composite code. By coding with a subcode coder and a supercode coder, a coder is reconfigurable by selecting different subcodes or supercodes. Communication systems and methods using composite codes are also described.

Abstract: Methods and apparatus for optical communication are disclosed. An optical data stream is encoded to produce an optical data stream having a predetermined time-wavelength spectrum. Two or more encoded data streams are combined in a transmission medium (e.g., optical fiber) and the combined data stream is decoded with decoders corresponding to the encoding of the data streams, producing decoded outputs. The decoded outputs include a portion corresponding to a selected data stream as well as a portion corresponding to unselected data streams (crosstalk). A nonlinear detector receives the decoded outputs and rejects crosstalk. Coders produce temporal delays and phase shifts specified by a time-wavelength code for, the spectral components of an input optical signal. Some coders convert optical signals encoded with a first time-wavelength code into an output corresponding to a second time-wavelength code. Temporal delays and phase shifts can be selected to compensate for dispersion in a transmission medium.

Abstract: Faults, dimensions and other characteristics of a material or structure are sensed by a coherent beam's reflection from the material during ultrasonic or very fast vibration. The reflected beam acquires a phase substantially different from its original phase and from the phase of a reference beam split from the common source beam. The reflected beam and the reference beam are superimposed by diffraction in a photorefractive polymer composite adaptive holographic beamsplitter, and the superimposed beams are detected by a photodetector capable of detecting small interference changes from ultrasonic surface displacements or perturbations. An apparatus and method defining an improved homodyne interferometer for performing the method is described.

Abstract: Methods and apparatus are provided for the recognition of an optical signal that is encoded with a specified temporal pattern. Nonlinear optical interactions and time-integrating optical detectors are used to identify temporally short correlation peaks in an optical signal in an optical communication system without temporally resolving the correlation signal. The apparatus includes means for decoding an encoded optical waveform, a time-integrating nonlinear detection system, a time-integrating linear detection system for proper normalization, and thresholding electronics that produce voltage pulses corresponding to the presence of specified waveforms at the detector input.