Abstract: A miniature WDM add/drop multiplexer and its manufacture is described. The device has a plurality of wavelength-dependent filters in the form of thin-film filters mounted to a core frame with the end sections of the input/output optical fiber and other optical fibers associated with each of the filters. The stresses associated with the filters are accounted for. The core frame is sealed, together with the overall package assembly, to provide for long-term reliability of the device. The described device and method of manufacture is also generally applicable to WDM multiplexers and demultiplexers.

Abstract: A polarization element and a polarization-sensitive optical isolator are integrated to form an integrated VOA. A preferred embodiment uses a liquid crystal cell as the polarization element to which is attached an optical isolator core of a first polarizer, Faraday rotator, and second polarizer. Voltage on the liquid crystal cell electrodes controls the amount of polarized light from the liquid crystal cell passing through the first polarizer and light in the opposite direction is blocked. The integrated VOA can be mounted within a laser device package so that the power of the source laser diode on the output fiber can be controlled and yet the laser diode is protected from light undesirably entering laser device package through the output fiber.

Abstract: Miniature optical devices, including circulator array devices, are fabricated using thin film coating technology. A typical optical device includes two refraction elements arranged opposite each other along a propagation axis and coupled on opposite ends to first and second polarization orientation elements with first and second PBS elements are coupled to the first and second polarization orientation elements, respectively. The refraction elements include complementary Wollaston Prism elements or Rochon Prism elements. Each polarization orientation element includes a Faraday rotator element, and in some embodiments, a half-wave plate formed using thin film coating techniques. The Faraday rotator elements are periodically poled in some embodiments using selective poling techniques to create oppositely oriented magnetic domains so that polarization rotations of 45° in both clockwise and counter-clockwise directions can be simultaneously achieved on the same magnetic garnet.

Abstract: Cholesteric liquid crystal cell units are used for reflecting or transmitting incident light responsive to control signals. A cholesteric liquid crystal cell unit has a first cholesteric liquid crystal cell and a second cholesteric liquid crystal cell. The second cholesteric liquid crystal cell respectively reflects or transmit lights from the first cholesteric liquid crystal cell responsive to a control signal when the first cholesteric liquid crystal cell reflects circularly polarized light of one state or transmits the incident light. In one embodiment of the cell unit, a &pgr;-phase waveplate element is located between the first and second cholesteric liquid crystal cells. With the cholesteric liquid crystal cell units, devices such as optical switches, and WDM add/drop multiplexers, and optical switch systems with arrays of input and output optical fibers between a switching matrix formed by the cholesteric liquid crystal cell units, may be constructed.

Abstract: Cholesteric liquid crystal cell units are used for reflecting or transmitting incident light responsive to control signals. A cholesteric liquid crystal cell unit has a first cholesteric liquid crystal cell and a second cholesteric liquid crystal cell. The second cholesteric liquid crystal cell respectively reflects or transmit lights from the first cholesteric liquid crystal cell responsive to a control signal when the first cholesteric liquid crystal cell reflects circularly polarized light of one state or transmits the incident light. In one embodiment of the cell unit, a &pgr;-phase waveplate element is located between the first and second cholesteric liquid crystal cells. With the cholesteric liquid crystal cell units, devices such as optical switches, and WDM add/drop multiplexers, and optical switch systems with arrays of input and output optical fibers between a switching matrix formed by the cholesteric liquid crystal cell units, may be constructed.

Abstract: A miniature fiberoptic filter and manufacturing method is disclosed. Two aligned optical fibers, each with a step index multimode optical fiber segment and a graded index multimode optical fiber segment attached to the corresponding optical fiber, form the filter. The lengths of the step index and graded index multimode optical fiber segments define a collimation and focusing function for light from and to the optical fibers, and dielectric coatings covering the free end surface of the graded index multimode optical fiber segment of one optical fiber define a wavelength-dependent optical filter. The optical fibers are arranged and oriented so that light from the core of the first optical fiber passing through the plurality of dielectric coatings enters the core of the second optical fiber.

Abstract: A temperature compensation circuit arrangement for liquid crystal cells in optical devices is presented. In an optical device, a liquid crystal cell typically manipulates the optical signals according to an output optical property, such as attenuation, responsive to an AC voltage source electrical signal. A feedback circuit arrangement is connected to the liquid crystal cell and controls the current through the liquid crystal cell with respect to temperature by a predetermined control equations for the output optical property so that the device manipulates the optical signals independently of temperature. The current follows the control equations, which are empirically determined with respect to temperature for one equation.

Abstract: Miniature optical devices, including circulator array devices, are fabricated using thin film coating technology. A typical optical device includes two refraction elements arranged opposite each other along a propagation axis and coupled on opposite ends to first and second polarization orientation elements with first and second PBS elements are coupled to the first and second polarization orientation elements, respectively. The refraction elements include complementary Wollaston Prism elements or Rochon Prism elements. Each polarization orientation element includes a Faraday rotator element, and in some embodiments, a half-wave plate formed using thin film coating techniques. The Faraday rotator elements are periodically poled in some embodiments using selective poling techniques to create oppositely oriented magnetic domains so that polarization rotations of 45° in both clockwise and counter-clockwise directions can be simultaneously achieved on the same magnetic garnet.

Abstract: Miniature optical devices, including circulator array devices, are fabricated using thin film coating technology. A typical optical device according to the present invention includes a spatial walkoff plate (SWP) coupled on opposite ends to first and second polarization orientation elements. First and second polarization beam splitter (PBS) elements are coupled to the first and second polarization orientation elements, respectively. The PBS elements are formed using thin film coating techniques and each includes an array of port coupling regions for coupling to an array of input/output fiber port assemblies. The SWP may be formed using thin film coating techniques or cut from a birefringent single crystal. Each polarization orientation element includes a Faraday rotator element, and in some embodiments, each also includes a wave plate formed using thin film coating techniques.

Abstract: An EDFA with integrated input and output modules is presented. The integrated input module has a packaged pump laser diode mounted to the metal EDFA package to provide a heat sink for the pump laser diode which sends the pump laser light over a optical fiber section connected to the amplifying erbium-doped optical fiber section. The fiber section is formed from an optical fiber which better matches the transmission modes in the erbium-doped optical fiber section and has an end subsection of the single mode fiber for a larger numerical aperture. Collimating lenses also increase the coupling efficiency of the laser diode to the erbium-doped fiber section. The integrated output module has a photodiode with a tap filter to monitor the output power of the EDFA, an optical isolator to prevent interference in the erbium-doped optical fiber section. With a twin optical isolator, the integrated input and output modules can be arranged in different ways and combinations with the erbium-doped optical fiber section.

Abstract: A temperature compensation circuit arrangement for liquid crystal cells in optical devices is presented. In an optical device, a liquid crystal cell typically manipulates the optical signals according to an output optical property, such as attenuation, responsive to an AC voltage source electrical signal. A feedback circuit arrangement is connected to the liquid crystal cell and controls the current through the liquid crystal cell with respect to temperature by a predetermined control equations for the output optical property so that the device manipulates the optical signals independently of temperature. The current follows the control equations, which are empirically determined with respect to temperature for one equation.

Abstract: A miniature fiberoptic filter and its manufacturing method is disclosed. The filter has a first optical fiber with a step index multimode optical fiber segment attached to the first optical fiber and a graded index multimode optical fiber segment attached to the step index multimode optical fiber segment. The lengths of the step index and graded index multimode optical fiber segments define a collimation and focusing function for light from and to the first optical fiber and dielectric coatings cover the free end surface of the graded index multimode optical fiber segment to define a wavelength-dependent optical filter. The miniature fiberoptic filter also has a second optical fiber with a step index multimode optical fiber segment attached to the second optical fiber, and a graded index multimode optical fiber segment attached to the step index multimode optical fiber segment.

Abstract: An improved optic attenuator controllably filters an optical signal after the signal has been expanded and collimated. The optical signals are preferably expanded and refocused by a single GRIN lens, the signal passing through a variable filter between the GRIN lens and a reflector, and again between the reflector and the GRIN lens. Both the input and output fibers can be held within a single sleeve in alignment with the GRIN lens. The amount of attenuation can be indicated by a potentiometer.

Abstract: The present invention provides for an optical waveguide device comprising a plurality of step-chirped, sampled fiber Bragg gratings which are chirped in a step-wise manner from one sampling segment to the next according to a chirp rate. Each sampling segment has a uniform grating period within the sampling segment. The step-chirped grating chirp rate may be selected to compensate for dispersion of signals over a transmission fiber connected to the optical waveguide device. The use of the step-chirped, sampled grating relaxes the tight chirp requirement of the chirped, sampled grating. The sampled grating may be step-chirped by writing an initial sampling segment on the fiber, and then stretching the fiber before writing each subsequent sampling segment. After writing the sampling segments, the fiber is returned to its original length, so that subsequently written sampling segments after each stretch have increasingly smaller grating periods.

Abstract: Miniature optical devices, including circulator array devices, are fabricated using thin film coating technology. A typical optical device according to the present invention includes a spatial walkoff plate (SWP) coupled on opposite ends to first and second polarization orientation elements. First and second polarization beam splitter (PBS) elements are coupled to the first and second polarization orientation elements, respectively. The PBS elements are formed using thin film coating techniques and each includes an array of port coupling regions for coupling to an array of input/output fiber port assemblies. The SWP may be formed using thin film coating techniques or cut from a birefringent single crystal. Each polarization orientation element includes a Faraday rotator element, and in some embodiments, each also includes a wave plate formed using thin film coating techniques.

Abstract: Miniature optical devices, including circulator array devices, are fabricated using thin film coating technology. A typical optical device according to the present invention includes two refraction elements arranged opposite each other along a propagation axis and coupled on opposite ends to first and second polarization orientation elements with first and second polarization beam splitter (PBS) elements are coupled to the first and second polarization orientation elements, respectively. The refraction elements include complementary Wollaston Prism elements or complementary Rochon Prism elements. Each polarization orientation element includes a Faraday rotator element, and in some embodiments, each also includes a half-wave plate formed using thin film coating techniques.

Abstract: Cholesteric liquid crystal cell units are used for reflecting or transmitting incident light responsive to control signals. A cholesteric liquid crystal cell unit has a first cholesteric liquid crystal cell and a second cholesteric liquid crystal cell. The second cholesteric liquid crystal cell respectively reflects or transmit lights from the first cholesteric liquid crystal cell responsive to a control signal when the first cholesteric liquid crystal cell reflects circularly polarized light of one state or transmits the incident light. In one embodiment of the cell unit, a &pgr;-phase waveplate element is located between the first and second cholesteric liquid crystal cells. With the cholesteric liquid crystal cell units, devices such as optical switches, and WDM add/drop multiplexers, and optical switch systems with arrays of input and output optical fibers between a switching matrix formed by the cholesteric liquid crystal cell units, may be constructed.

Abstract: The invention provides improved optical devices, systems, and methods for controllably varying an optical characteristic of an optical signal, particularly for filtering and generating optical signals about a narrow tunable central wavelength. Thin film multi-cavity Fabry-Perot bandpass filters have film thicknesses which vary so as to vary the center wavelength of the filter's pass range. Novel micro lenses and lens arrangements avoid transmission of optical signals through a large area of the optical filter, which would widen the effective pass bandwidth and reduce coupling efficiency. These bandpass filtering techniques can be used in an external cavity laser system to provide a tunable laser source.

Abstract: The present invention provides for an optical waveguide device comprising a gratings, primarily in the form of fiber Bragg gratings, which are sampled, interleaved and chirped to achieve different functions. By interleaving sampled fiber Bragg gratings, each with a grating period which differs from the others by an amount corresponding to a multiple of a channel spacing, a predetermined and useful optical spectrum can be produced for the optical waveguide device. By making the sample periods for the fiber Bragg gratings different from each other, the resulting reflection spectrum has missing reflection peaks. A bandpass filter can be effectively created. Furthermore, by discretely varying the grating periods of sampled fiber Bragg gratings at intervals along the optical fiber containing the gratings, a more uniform optical spectrum is produced for the optical waveguide device.

Abstract: Improved optical devices, systems, and methods for selectively directing optical signals generally based on a Mach-Zehnder interferometer. Through accurate control of the phase relationship, the Mach-Zehnder interferometer allows optical signals to either be cumulatively combined so as to enhance the transmitted signal strength, or destructively combined so as to effectively prevent transmission from an optical signal port. This phase relationship can be controlled using a nonreciprocal device having a pair of retarder plates disposed along one of the two legs of the Mach-Zehnder interferometer so as to provide an optical isolator or circulator.