Abstract: An optical switch includes a plurality of first optical fibers, a plurality of second optical fibers, a first MEMS array, and a second MEMS array. The first MEMS array is optically coupled with the first optical fibers to receive optical signals from the first optical fibers and to direct the optical signals, wherein the first MEMS array defines a first array incidence angle between a normal direction to the first MEMS array and a direction of the received optical signals. The second MEMS array is optically coupled with the first MEMS array to receive the directed optical signals and to re-direct the directed optical signals with the second optical fibers wherein the second MEMS array defines a second array incidence angle between a normal direction to second MEMS array and a direction of the re-directed optical signals. The configuration of the components is provided to provide reduced optical losses.

Abstract: A temperature control system is provided for an optical switch including steerable micro-mirrors. The system includes at least one sensor and associated sensing circuitry for measuring the temperature of a micro-mirror or a region of a substrate near a micro-mirror. The system also includes a controller that responds to a signal provided by the sensing circuitry. The controller response may include activating heating or cooling devices the region that is sensed to adjust the temperature of the region.

Abstract: An optical network element uses steerable mirrors in an optical switch to couple optical inputs and optical outputs. An optical switch has at least one array of the steerable mirrors, which can be oriented so as to reflect an optical signal between an input and an output. A shorter optical path between the input and the output reduces optical losses because optical losses in an optical switch using mirrors are directly proportional to the total length of the optical path. Reducing the optical path depends upon the switching tilt angle used in steering the mirrors. But tilting the micro-mirrors near their critical tilt angle or repeatedly across large tilt angles will degrade reliability or control. However, the total optical path can be shortened and the reliability of steerable mirrors can be maintained or increased if at least some of the micro-mirrors in an array are offset angled.

Abstract: An optical network element using arrays of mirrors in an optical switch. A lens system is placed in between the mirror arrays and optical signals are passed through the lens system in an off-axis manner in order to increase switching capacity so that larger arrays of mirrors can be used, shorten the optical path through the switch or a combination of both.

Abstract: An optical network element using steerable mirrors in an optical switch. A steerable mirror in the switch is connected to a potential bias having a magnitude greater than zero in order to reduce the operating potential of the integrated control system that steers the mirror.

Abstract: An optical switch having a fiber/lens array and a switching substrate may be properly aligned using one or more grating(s) provided on the switching substrate. The grating(s) may be designed to have a predetermined response when the fiber/lens array and switching substrate are properly aligned. For example, the grating(s) may reflect incident light back into an input fiber, where the back-reflected light may be detected. Accordingly, the position of the switching substrate and/or fiber/lens array may be adjusted until back reflected light having predetermined power is detected.

Abstract: The position of a micro-mirror, for example, in an optical switch, may be monitored using an optical position control signals that are detected by a detector arrangement. The position of the micro-mirror may be adjusted by detecting the position of the beam spot and comparing the detected position to a desired position.

Abstract: An optical switch having a fiber/lens array and a switching substrate may be properly aligned using one or more static mirrors or photodetectors provided on the switching substrate. The static mirrors may be designed to reflect incident light back into an input fiber, where the back reflected light may be detected, or to a detector provided at a predetermined position. Accordingly, the position of the switching substrate and/or fiber/lens array may be adjusted until reflected light having predetermined power is detected. In another embodiment, the position of the switching substrate and/or fiber/lens array may be adjusted until predetermined power is detected by the photodetectors provided on the switching substrate.

Abstract: An integrated device includes a micro-lens and an opto-electronic device can be formed on a single substrate. The opto-electronic device may be one or more photodetectors and the micro-lens may be shaped to allow partial absorption of light incident to the micro-lens by the photodetectors. The integrated device is capable of simultaneously performing position detection, signal monitoring, and focusing/collimation.

Abstract: A structure and method for an optical switch is provided that includes providing sidewall electrodes with steerable micro-mirrors to position and control micro-mirror movement. The structure and method includes using the sidewall electrodes in conjunction with electrodes underlying a micro-mirror to sense capacitance present between a micro-mirror and underlying electrodes and/or sidewall electrodes, and driving the electrodes underlying the micro-mirror and the sidewall electrodes to move the micro-mirror into an angular position. The electrode structures and methods of driving them may be used in systems with closed loop feedback control to reduce transient mirror settling time and provide substantial immunity to system perturbations when micro-mirrors switch an optical signal from an input fiber to an output fiber of the optical switch, or when a micro-mirror is held at an angular position over long time scales.

Abstract: An optical device includes a compact and low cost integration of a movable micro-mirror and control mechanisms. The optical devices may be manufactured using microelectromechanical system (MEMS) technology. The optical device may be used in a high port count optical switch, such as an optical cross connect for use in an optical telecommunication system, that uses beam steering to couple light from input fibers to selected output fibers.

Abstract: An optical network and an optical amplifier system provide flattened gain, constant per channel output power, and compensation for variable span losses. The optical amplifier system is disposed in a transmission line of the optical network. The optical amplifier includes a first and second stage optical feedback loop amplifiers.

Abstract: An optical cross-connect system and method allows service providers to economically and efficiently handle capacity upgrades to meet future demands. The optical cross-connect can be embodied as a three-stage switch having a first, a middle, and a last stage. Capacity upgrades may be accomplished by adding additional first and last stage switches to meet increased demand and by replacing the middle stage switches. Accordingly, the original first and last stage switches may be retained in the upgraded optical cross-connect. The resulting optical cross-connect may include both optical and electronic components and the upgrade may be performed without interrupting service.

Abstract: A wavelength-interchanging cross-connect for a wavelength-division multiplexing (WDM) optical communication system including both transparent optical paths and opaque paths through an electronic switching network, such as a high-speed digital cross-connect switch (DCS), including matching opto-electronic conversions of the data signal. All-optical switching is performed on the input and output sides, for example, by mechanically actuated fiber switches. The DCS, receiving optical inputs from the input optical switches and providing optical outputs to the output optical switches, performs switching in the electrical domain and can perform wavelength conversion of the signals passing through it. The DCS also provides for access to electrical add/drop lines for interfacing to a client. The transparent optical path, which can be either direct or through an optical switch, transfers a signal without regard to its format from the input to the output of the switching system.

Abstract: A liquid-crystal switching element relying upon a segmented liquid-crystal polarization modulator, at least one frequency-dispersive grating and one or more polarization-dispersive elements, such as Wollaston prisms, to switch separate wavelength-divided signals among four optical paths. The switching is done complementally between the fibers of each pair, and the same switching is done for the two pairs. According to the invention, all four beams can be processed by a single set of serial optics. The invention is particularly useful as an optical interconnect between two optical fiber communications rings in which each ring includes two counter-rotating fibers. The invention advantageously uses a dielectric thin-film beam splitter for one of the polarization-dispersive elements and a Wollaston prism for the other.

Abstract: An optical matrix protection system is described. Optical signals that are cross-connected by a N×N matrix switch are routed through alternative protection paths using an optical matrix protection system. The optical matrix protection system includes a N×1 optical switch and a 1×N optical switch. An input port of the 1×N optical switch is coupled to an output port of the N×1 optical switch. Input ports of the N×1 optical switch are connected to a plurality of 1×2 optical switches, which selectively switch input optical signals to either the N×N matrix switch or to the N×1 optical switch. Output ports of the 1×N optical switch are connected to a plurality of 2×1 optical switches, which selectively switch optical signals from either the N×N matrix switch or laid the 1×N optical switch to an output line.

Abstract: A multi-wavelength optical receiver including multiple photodetectors receiving different ones of a multi-wavelength signal. For each wavelength-dedicated photodetector, a separate electronic receiver circuitry is provided including a current-to-voltage converting input transistor and an emitter-follower output transistor arranged as an operational amplifier with a feedback resistor.

Abstract: A protection system for a micro electro-mechanical system (MEMS) cross-bar switch is described. Optical signals that are cross-connected by a N×N optical matrix switch are routed through alternative protection paths using protection switch elements. The protection switch elements are incorporated as part of the silicon wafer based fabricated structure that forms the N×N optical matrix. The protection switch elements enable the N×N optical matrix switch to recover from one or more failures in switch elements of the N×N optical matrix using alternative protection paths that have the same path length as the original optical path.

Abstract: A reconfigurable multiwavelength network element includes a first demultiplexer unit for demultiplexing a first multiplexed optical signal from a first optical fiber into a first plurality of optical outputs; a second demultiplexer unit for demultiplexing a second multiplexed optical signal from a second optical fiber into a second plurality of optical outputs; a first multiplexer unit having first optical inputs for receiving signals to be multiplexed together; a second multiplexer unit having second optical inputs for receiving signals to be multiplexed together; and a cross-connect unit having first and second portions, the first portion directing signals received from at least a first one of the first plurality of optical outputs and a first one of the second plurality of optical outputs to a first one of the first optical inputs and a first one of the second optical inputs, the second portion directing signals received from at least a second one of the first plurality of optical outputs and a second one

Abstract: A liquid crystal, cell having plates defining a gap between them which is filled with a liquid crystal, especially a twisted nematic. The plates are made non-parallel to a predetermined degree so that the liquid crystal assumes a wedge shape, producing different effective thicknesses of the liquid crystal depending on the lateral position within the cell. In use, a narrow beam irradiates a portion of the cell, and the cell is positioned along the wedge direction so as to optimize the cell performance. The invention is particularly useful with a liquid-crystal multi-wavelength switch, which requires extinction ratios between the two states of the cell.