Abstract: A polarization insensitive optical phase modulator is provided including a glass substrate; a liquid crystal element; a first electrode on a first surface of the liquid crystal element adjacent the glass substrate; a second electrode on a second surface of the liquid crystal element, opposite the first surface, the first and second electrodes supplying an electric potential across the liquid crystal element to drive liquid crystals in a predetermined configuration; and a silicon backplane on the second electrode opposite the liquid crystal element. The first electrode is a transparent electrode to a selected wavelength and is on a surface of the glass substrate. The second electrode includes individually addressable pixels and reflection metal mirrors on pixel surfaces and is on a surface of the silicon backplane.

Abstract: A polarization insensitive optical phase modulator is provided including a glass substrate; a liquid crystal element; a first electrode on a first surface of the liquid crystal element adjacent the glass substrate; a second electrode on a second surface of the liquid crystal element, opposite the first surface, the first and second electrodes supplying an electric potential across the liquid crystal element to drive liquid crystals in a predetermined configuration; and a silicon backplane on the second electrode opposite the liquid crystal element. The first electrode is a transparent electrode to a selected wavelength and is on a surface of the glass substrate. The second electrode includes individually addressable pixels and reflection metal mirrors on pixel surfaces and is on a surface of the silicon backplane.

Abstract: Embodiments of the present invention provide a liquid crystal grating-based optical switching apparatus, including an input collimator, an input polarization beam splitter, an input quarter-wave plate, a liquid crystal grating, an output quarter-wave plate, an output polarization beam splitter, and an output collimator. A transmission path is selected for an optical signal by changing a voltage of a liquid crystal grating so that the optical signal is output to a selected output.

Abstract: Embodiments of the present invention provide a variable optical attenuator. The variable optical attenuator includes: a collimator, a switchable polarization grating, a reflector, and a voltage controller for adjusting a voltage between electrodes at both ends of a liquid crystal layer of the switchable polarization grating, where the collimator, the switchable polarization grating, and the reflector are disposed successively; the collimator is configured to receive incident light and output the incident light to the switchable polarization grating; the switchable polarization grating is configured to diffract the incident light for one time and then perform emission onto the reflector; the switchable polarization grating is further configured to diffract, for one time, a beam reflected back by the reflector, and then emit resulting diffracted light; and the collimator is further configured to receive the diffracted light and output the diffracted light.

Abstract: Embodiments of the present invention provide a variable optical attenuator. The variable optical attenuator includes: a collimator, a switchable polarization grating, a reflector, and a voltage controller for adjusting a voltage between electrodes at both ends of a liquid crystal layer of the switchable polarization grating, where the collimator, the switchable polarization grating, and the reflector are disposed successively; the collimator is configured to receive incident light and output the incident light to the switchable polarization grating; the switchable polarization grating is configured to diffract the incident light for one time and then perform emission onto the reflector; the switchable polarization grating is further configured to diffract, for one time, a beam reflected back by the reflector, and then emit resulting diffracted light; and the collimator is further configured to receive the diffracted light and output the diffracted light.

Abstract: Embodiments of the present invention provide a liquid crystal grating-based optical switching apparatus, including an input collimator, an input polarization beam splitter, an input quarter-wave plate, a liquid crystal grating, an output quarter-wave plate, an output polarization beam splitter, and an output collimator. A transmission path is selected for an optical signal by changing a voltage of a liquid crystal grating so that the optical signal is output to a selected output.

Abstract: The present invention discloses a beam processing device, a beam attenuation and switching device, and an optical wavelength selective switch system. The beam processing device in the present invention includes a polymer polarization grating and a quarter-wave plate array. Splitting and adjustment of a beam polarization state may be implemented by using the polymer polarization grating and the quarter-wave plate array. The beam attenuation and switching device includes a switchable polarization grating and an optical path angle adjustment device, or includes a half-wave liquid crystal plate, a quarter-wave plate, a polymer polarization grating, and an optical path angle adjustment device.

Abstract: Apparatus and method embodiments are provided for implementing a wavelength selective switch (WSS). The embodiments use combinations of switchable polarization grating (SPG) and LC cells and combinations of polymer polarization grating (PPG) and LC cells to achieve 1×N WSS systems. An embodiment optical switch includes a liquid crystal cell and a polymer polarization grating (PPG) cell adjacent to the liquid crystal cell. The PPG includes a glass substrate, a photo-alignment layer overlying the glass substrate and comprising photosensitive polymer that has been physically altered by exposure using two interfering light beams with opposite handedness of circular polarization, and a polymerized liquid crystal layer overlying the photo-alignment layer on an opposite side of the glass substrate, the polymerized liquid crystal layer has been physically altered by illumination using a uniform light beam.

Abstract: Apparatus and method embodiments are provided for implementing a wavelength selective switch (WSS). The embodiments use combinations of switchable polarization grating (SPG) and LC cells and combinations of polymer polarization grating (PPG) and LC cells to achieve 1×N WSS systems. An embodiment optical switch includes a liquid crystal cell and a polymer polarization grating (PPG) cell adjacent to the liquid crystal cell. The PPG includes a glass substrate, a photo-alignment layer overlying the glass substrate and comprising photosensitive polymer that has been physically altered by exposure using two interfering light beams with opposite handedness of circular polarization, and a polymerized liquid crystal layer overlying the photo-alignment layer on an opposite side of the glass substrate, the polymerized liquid crystal layer has been physically altered by illumination using a uniform light beam.

Abstract: Apparatus and method embodiments are provided for implementing a wavelength selective switch (WSS). The embodiments use combinations of switchable polarization grating (SPG) and LC cells and combinations of polymer polarization grating (PPG) and LC cells to achieve 1×N WSS systems. An embodiment optical switch includes a liquid crystal cell and a SPG cell adjacent to the liquid crystal cell. The SPG includes liquid crystal material between two photo-alignment layers, an electrode layer overlying each photo-alignment layer, and a glass substrate overlying each electrode layer. An embodiment method includes polarizing an incident light beam at a circular polarization before diffracting, at a polarization grating, the polarized incident light beam in a determined angle that corresponds to a diffraction order in accordance to the circular polarization of the incident light beam and a hologram pattern direction formed inside the polarization grating.

Abstract: An optical device for processing an optical signal includes a crystal wedge, a polarization modulator, and a reflective element. The crystal wedge spatially separates an input optical signal into a first beam component having a first polarization state and a second beam component having a second polarization state. The crystal wedge has an optical axis arranged at an optical axis angle such that the first beam component and the second beam component converge. The polarization modulator changes the polarization state of the first beam component and the polarization state of the second beam component in response to a control signal. The reflective element reflects the first beam component and the second beam component such that the crystal wedge spatially recombines a portion of the first beam component having the second polarization state with a portion of the second beam component having the first polarization state to form an output optical signal.

Abstract: Devices and methods for equalizing the gain of an optical amplifier are described. For devices including harmonic filters that are controllable by amplitude control voltages and phase control voltages, techniques for controlling the amplitude control voltages and phase control voltages are presented. Additionally, device architectures are described by which an incoming optical signal is equalized to compensate for uneven gain in prior amplifiers or other optical components, and in which the incoming optical signal is received at a beam displacer and separated into orthogonal component beams, wherein the beams are counter-propagated through the equalizer in opposite directions through the same spatial path so as to minimize or eliminate the effects spatially dependent imperfections in the equalizer.

Abstract: An optical processing device includes a polarization modulator operable to change a polarization state of an input optical signal based at least in part on a control voltage applied to a liquid crystal material associated with the polarization modulator. The control voltage is based at least in part on a temperature of the liquid crystal material.

Abstract: An optical routing switch uses two liquid crystal cells that can produce offsetting rotations of the polarization of the input beam to provide fast, symmetrical switching. The input beam is first polarized and then passes through both liquid crystal cells in series. Both liquid crystal cells have two states (e.g., voltage-off and voltage-on) in which the beam polarization is rotated by predetermined angles (e.g., 0° and 90°), but in opposing rotational directions. A controller selectively rotates the LC cells through a sequence of steps, beginning with a “through” state in which both LC cells are in the first state. The polarization rotations provided by both liquid crystal cells offset one another so the beam polarization remains essentially unchanged. The LC cells can be rapidly switched to a “cross” state in which only one of the LC cells is changed to the second state and the polarization of the beam is rotated by a predetermined degree.

Abstract: Devices and methods for equalizing the gain of an optical amplifier are described. For devices including harmonic filters that are controllable by amplitude control voltages and phase control voltages, techniques for controlling the amplitude control voltages and phase control voltages are presented. Additionally, device architectures are described by which an incoming optical signal is equalized to compensate for uneven gain in prior amplifiers or other optical components, and in which the incoming optical signal is received at a beam displacer and separated into orthogonal component beams, wherein the beams are counter-propagated through the equalizer in opposite directions through the same spatial path so as to minimize or eliminate the effects spatially dependent imperfections in the equalizer.

Abstract: An optical equalizer for use primarily with an erbium-doped fiber amplifier has an initial polarizer that convert the input beam to a predetermined polarization, followed by a series of dynamically-adjustable sinusoidal filters that provide attenuation as a sinusoidal function of beam wavelength. Each of the sinusoidal filters has a first liquid crystal cell adjustably rotating the polarization of the beam from the preceding polarizer. This is followed by a second optical element that retards the beam as a sinusoidal function of beam wavelength. For example, the second optical element can be a birefringent crystal that provided a fixed degree of retardance to the beam and a second liquid crystal cell that provides a variable degree of retardance, thereby allowing adjustment of the center frequency of the sinusoidal function. Finally, a third liquid crystal cell adjustably rotates the polarization of the beam.

Abstract: An optical equalizer for use primarily with an erbium-doped fiber amplifier has an initial polarizer that convert the input beam to a predetermined polarization, followed by a series of dynamically-adjustable sinusoidal filters that provide attenuation as a sinusoidal function of beam wavelength. Each of the sinusoidal filters has a first liquid crystal cell adjustably rotating the polarization of the beam from the preceding polarizer. This is followed by a second optical element that retards the beam as a sinusoidal function of beam wavelength. For example, the second optical element can be a birefringent crystal that provided a fixed degree of retardance to the beam and a second liquid crystal cell that provides a variable degree of retardance, thereby allowing adjustment of the center frequency of the sinusoidal function. Finally, a third liquid crystal cell adjustably rotates the polarization of the beam.

Abstract: The disclosure describes an optically addressable spatial light modulator (OASLM) having a light sensitive member and a distorted helix ferroelectric liquid crystal (DHFLC). In a first embodiment a hydrogenated amorphous silicon (a-Si:H) photodiode layer is in physical contact with the DHFLC layer. In another embodiment an integrated circuit member includes a photosensitive area and an associated metal pad for each OASLM pixel, the metal pads in physical contact with corresponding DHFLC pixel areas. In the first embodiment, a low magnitude AC voltage (less than three to seven volts peak to peak) is connected to the OASLM as operating voltage, preferably in the absence of a DC offset voltage. The OASLM pixel areas of the OASLM are selectively addressed by a writing light wavefront, to thereby activate corresponding pixel areas of the light sensitive member.