Abstract: The present invention relates generally to semiconductor lasers and laser scanning systems and, more particularly, to schemes for controlling wavelength in semiconductor lasers. According to one embodiment of the present invention, a method of minimizing laser wavelength variations in a semiconductor laser is provided. According to the method, one or more of the laser drive currents is configured to comprise a drive portion and a wavelength recovery portion. The wavelength recovery portion of the drive current comprises a recovery amplitude IR that is distinct from the drive amplitude ID and a recovery duration tR that is less than the drive duration tD. The recovery amplitude IR and duration tR are sufficient to recover carrier density distribution distorted by gain compression effects prior to recovery. Additional embodiments are disclosed and claimed.

Abstract: Methods of controlling semiconductor lasers are provided where the semiconductor laser generates a wavelength-modulated output beam ?MOD that is directed towards the input face of a wavelength conversion device. The intensity of a wavelength-converted output ?CONV of the device is monitored as the output beam of the laser is modulated and as the position of the modulated output beam ?MOD on the input face of the wavelength conversion device is varied. A maximum value of the monitored intensity is correlated with optimum coordinates representing the position of the modulated output beam ?MOD on the input face of the wavelength conversion device. The optical package is operated in the data projection mode by directing an intensity-modulated laser beam from the semiconductor laser to the wavelength conversion device using the optimum positional coordinates. Additional embodiments are disclosed and claimed. Laser controllers and projections systems are also provided.

Abstract: Particular embodiments of the present invention relate generally to semiconductor lasers and laser scanning systems and, more particularly, to schemes for controlling semiconductor lasers. According to one embodiment of the present invention, a laser is configured for optical emission of encoded data. At least one parameter of the optical emission is a function of a drive current IGAIN injected into the gain section of the semiconductor laser and one or more additional drive currents I/VPHASE, I/VDBR. Mode selection in the semiconductor laser is altered by perturbing at least one of the additional drive currents I/VPHASE, I/VDBR with a perturbation signal I/VPTRB to alter mode selection in the semiconductor laser such that a plurality of different emission modes are selected in the semiconductor laser over a target emission period.

Abstract: Particular embodiments of the present invention relate generally to semiconductor lasers and laser scanning systems and, more particularly, to schemes for controlling semiconductor lasers. According to one embodiment of the present invention, a laser is configured for optical emission of encoded data. At least one parameter of the optical emission is a function of a drive current IGAIN injected into the gain section of the semiconductor laser and one or more additional drive currents I/VPHASE, I/VDBR. Mode selection in the semiconductor laser is altered by perturbing at least one of the additional drive currents I/VPHASE, I/VDBR with a perturbation signal I/VPTRB to alter mode selection in the semiconductor laser such that a plurality of different emission modes are selected in the semiconductor laser over a target emission period.

Abstract: The present invention relates generally to semiconductor lasers and laser scanning systems and, more particularly, to schemes for controlling wavelength in semiconductor lasers. According to one embodiment of the present invention, a method of minimizing laser wavelength variations in a semiconductor laser is provided. According to the method, one or more of the laser drive currents is configured to comprise a drive portion and a wavelength recovery portion. The wavelength recovery portion of the drive current comprises a recovery amplitude IR that is distinct from the drive amplitude ID and a recovery duration tR that is less than the drive duration tD. The recovery amplitude IR and duration tR are sufficient to recover carrier density distribution distorted by gain compression effects prior to recovery. Additional embodiments are disclosed and claimed.

Abstract: The present invention relates to methods for modulating a semiconductor laser and wavelength matching to a wavelength converter using monolithic micro-heaters integrated in the semiconductor laser. The present invention also relates to wavelength matching and stabilization in laser sources in general, without regard to whether the laser is modulated or whether second harmonic generation is utilized in the laser source. According to one embodiment of the present invention, a method of compensating for thermally induced patterning effects in a semiconductor laser is provided where the laser's heating element driving current IH is set to a relatively high magnitude when the laser's driving current ID is at a relatively low magnitude. Additional embodiments are disclosed and claimed.

Abstract: Chromatic dispersion of thin-film based mux/demux and add/drop modules can be reduced. Thin-film devices can be arranged in a specific order in the module. Multiple kinds of filters are used to remove “even” and “odd” channels, or other divisions of channels. At least one filter type can be designed for a higher dispersion in transmission but lower dispersion in reflection. At least another filter type can be designed in conjunction with the first filter type such that the sum of the dispersion from the reflection and that from transmission is as low as possible. This ensures that the overall dispersion of the odd and even channels is lower than what one can achieve with one uniform filter.

Abstract: Chromatic dispersion of thin-film based mux/demux and add/drop modules can be reduced. Thin-film devices can be arranged in a specific order in the module. Multiple kinds of filters are used to remove “even” and “odd” channels, or other divisions of channels. At least one filter type can be designed for a higher dispersion in transmission but lower dispersion in reflection. At least another filter type can be designed in conjunction with the first filter type such that the sum of the dispersion from the reflection and that from transmission is as low as possible. This ensures that the overall dispersion of the odd and even channels is lower than what one can achieve with one uniform filter.

Abstract: Filter gratings are formed in optical waveguides having photosensitive cores by exposing the cores to actinic radiation in the form of interfering beams having peak intensities that are relatively displaced along an optical axis of the waveguides. Each of the interfering beams has a single-lobed intensity profile and a degree of spatial coherence required to achieve a desired fringe contrast between the two relatively displaced beams. Index modulations in the photosensitive core match the illumination (interference) pattern of the radiation. The relative displacement of the interfering beams reduces side lobes of the gratings' spectral responses by leveling the average refractive index of the index modulations. A second exposure with the two beams but without the beams' interference effects further levels the average refractive index.

Abstract: Methods and apparatus for combining, adding, and/or dropping channels in optical communication systems that utilize thin film filters without the creation of deadbands, using fiber Bragg gratings and additional thin film optical filters, are described. According to one aspect of the invention, an optical filter is used to drop a wavelength range from an optical signal. Prior to the optical signal entering the optical filter, one or more fiber Bragg gratings and an optical circulator are used reflects a portion of the communications spectrum which would normally lie with the deadband region of the optical filter. According to another aspect of the present invention, an optical filter is used to combine a first optical signal and a second optical signal to form a combined optical signal. Neither the first optical signal nor the second optical signal includes channels within a deadband region of the optical filter.

Abstract: An optical device including an optical amplifier to amplify optical signals received through an optical input, and to supply the amplified optical signals from an optical output, and an optical filter component to compensate for variations in the gain spectrum of the optical amplifier that occur as a function of wavelength and operating temperature. The optical filter component includes a first optical filter having an athermalized transmission spectrum and a second optical filter having a transmission (or insertion loss) spectrum that varies as a function of operating temperature.

Abstract: Methods and apparatus for combining, adding, and/or dropping channels in optical communication systems that utilize thin film filters without the creation of deadbands, using fiber Bragg gratings and additional thin film optical filters, are described. According to one aspect of the invention, an optical filter is used to drop a wavelength range from an optical signal. Prior to the optical signal entering the optical filter, one or more fiber Bragg gratings and an optical circulator are used reflects a portion of the communications spectrum which would normally lie with the deadband region of the optical filter. According to another aspect of the present invention, an optical filter is used to combine a first optical signal and a second optical signal to form a combined optical signal. Neither the first optical signal nor the second optical signal includes channels within a deadband region of the optical filter.

Abstract: An optical device including an optical amplifier to amplify optical signals received through an optical input, and to supply the amplified optical signals from an optical output, and an optical filter component to compensate for variations in the gain spectrum of the optical amplifier that occur as a function of wavelength and operating temperature. The optical filter component includes a first optical filter having an athermalized transmission spectrum and a second optical filter having a transmission (of insertion loss) spectrum that varies as a function of operating temperature.

Abstract: An optical waveguiding fiber has a photosensitive core and a cladding that includes a photosensitive inner cladding region adjacent the core and an outer cladding region. The inner cladding region and the outer cladding region have substantially equal indices of refraction. The photosensitivity of the inner cladding region is sufficient to cause a modulation of the index of refraction of the inner cladding when exposed to ultraviolet light. In another aspect of the invention, the optical fiber includes a grating in the core, which extends radially into the inner cladding region. The core and the inner cladding region of the optical fiber are doped with concentrations of Ge and B sufficient to impart photosensitivity to the inner cladding region, and to result in an index of refraction in the inner cladding region substantially equal to the index of refraction of the outer cladding region.

Abstract: Optical gratings having a range of possible Bragg wavelengths can be produced using a single phase mask by exposing the mask to a non-collimated spatially filtered beam of light. A spatial filter removes high spatial frequency components from the beam, and a focusing system directs the filtered beam to a phase mask. A rate at which the beam is focused and a spacing between the phase mask and a photo-sensitive waveguide are varied to produce gratings in the waveguide having a range of possible periods.

Abstract: An optical waveguide sensor arrangement for sensing at least one physical parameter is provided. This arrangement comprises an optical waveguide having guided modes, lossy non-guided modes, and a long period grating coupling the guided modes to the lossy non-guided modes wherein the long period grating produces a wavelength transmission spectrum functionally dependent on the physical parameter sensed. A source means provides light to the optical waveguide sensor and an optoelectronic detector, which is positioned in an operable relationship to the optical waveguide sensor, detects light transmitted through the optical waveguide sensor. Lastly, a processing means is attached to the optoelectronic detector for correlating the wavelength transmission spectrum with a numerical value for the physical parameter sensed. The physical parameters sensed by the optical waveguide sensor include: temperature, strain, shape, refractive index and corrosion.