Xtellus, Inc.

Oclaro (New Jersey), Inc.

Finisar Corporation

Oclaro Technology Limited

Gil Cohen

Yossi Corem

Yaron Silberberg

Roey Harel

Seongwoo Suh

Seong Woo Suh

Manish Sharma

SeongWoo Suh

Boris Frenkel

Johnny Leung

An optical switch having multiple input and output ports directs any number of WDM signals, each arriving at a respective input port, to any one of the output ports. The optical switch includes an array of LC pixels, each positioned to receive a WDM signal transmitted through one of the ports, and an array of reflective elements, each associated with one of the LC pixels. The LC pixels are controlled to cause a WDM signal incident thereon to attain an attenuation state while an output of the WDM signal is being switched by an associated reflective element, such that when an output for a WDM signal is switched from a first port to a second port, the switching can be performed in a hitless manner.

Multi-pole optical signal switch

A multi-port wavelength selective switch includes a one dimensional array of input and output ports. The multi-port wavelength selective switch further includes a wavelength dispersive element configured to receive input optical signals from the input ports, and to disperse wavelength components thereof. Additionally, the multi-port wavelength selective switch includes an array of beam steering devices. Each beam steering device is controllable to a position at which the beam steering device directs a wavelength component of an input optical signal received through a first input port to an output port and directs the same wavelength component of an input optical signal received through a second input port away from all of the output ports.

Wavelength selective switch with multiple input/output ports

An optical switching device has multiple input ports and multiple output ports and is capable of switching a wavelength component from any of the input ports to any of the output ports. The optical switching device is configured with beam steering arrays that are controlled to provide the switching from any of the input ports to any of the output ports. The beam steering arrays may be microelectromechanical (MEMS) mirror arrays or liquid-crystal on silicon (LCOS) panels. In addition, an array of beam-polarizing liquid-crystal elements provides wavelength-independent attenuation.

Wavelength selective switch

An optical device compensates for decreased transmission of light caused by gaps between mirrors of a MEMS array. The optical device employs MEMS mirrors having non-reflecting regions on them disposed such that reflecting regions of the MEMS mirrors have substantially the same optical throughput, or an additional optical element having increased transmission at those spatial positions where light impinging on the gaps passes through. Alternatively, the optical device may employ a filter having spectral transmission characteristic with increased transmission at those wavelengths of dispersed light that impinge on the gaps.

WSS with pixel gap compensation

A fiber-optical, wavelength selective switch, especially for channel routing with equalization and blocking applications. The input signals are converted to light beams having predefined polarizations (). The beams are then laterally expanded (), and then undergo spatial dispersion in the beam expansion plane. The different wavelength components are directed through a polarization rotation device, pixilated along the wavelength dispersion direction such that each pixel operates on a separate wavelength. Each beam is passed into a pixilated beam steering array (), for directing each wavelength to a desired output port. The beam steering devices can be MEMS-based or Liquid crystal-based, or an LCOS array. When the appropriate voltage is applied to a pixel and its associated beam steering element, the polarization of the light passing through the pixel is rotated and the beam steered to couple to the selected output port.

Optical wavelength selective router

A collimator array using a molded element to hold the input fibers and to collimate the light. The input fibers are held within holes in one face of the element, and the collimation of the light emitted from the ends of the fibers is performed by an array of lenses appropriately located such that each lens collimates the light emitted from a fiber end. The lateral spacing between the holes is made to be equal to the lateral spacing between the lenses of the array. Since, in a molded element, this lateral spacing can be accurately provided, good alignment of the input fibers with the lenses can be achieved. The depths of the holes can be made such that when a fiber is inserted right to the bottom of a hole, the end of that fiber is accurately located such that the light emitted therefrom is collimated by the lens. This avoids the need for accurate manual alignment of the fibers of the array. Alternatively, the hole can be made slightly deeper than this predetermined depth, to provide some adjustment in the lens-fiber distance for adjusting the level of collimation.

Collimator array

An isolator assembly, for use internally within a multi-port optical switch, and which operates on a preselected number of input port channels. The assembly incorporates a sequence of a birefringent crystal with a half wave plate on part of its output face acting as a linear polarizer, a 45&#xb0; Faraday rotator element and a half wave plate aligned at 22.5&#xb0; to the polarization direction of the light rotated by the Faraday rotator. This arrangement ensures that any light spuriously returned from a reflective beam switching element of the switch is blocked from transmission out of the paths of light which the isolator assembly covers because of the orientation of the light polarization returned to the birefringent crystal. The isolator assembly is arranged such that it does not cover the beam path leading to the output port or ports, such that legitimate output beams are transmitted unhindered.

Optical devices with integral isolators

A wavelength selective switch, in which an input optical signal is wavelength-dispersed and polarization-split in two angularly oriented planes. A polarization rotation device, such as a liquid crystal polarization modulator, pixelated along the wave-length dispersive direction such that each pixel operates on a separate wavelength channel, rotates the polarization of the light signal passing through the pixel, according to the control voltage applied to that pixel. The polarization modulated signals are then wave-length-recombined and polarization-recombined by means of similar dispersion and polarization combining components as were used to respectively disperse and split the input signals. The direction of the output signal is determined by whether the polarization of a particular wavelength channel was rotated by the polarization modulator pixel, or not. In this way, a fast, wavelength dependent, optical switch is provided, capable of use in WDM switching applications.

Wavelength selective optical switch

A fiber optical device, whose wavelength profile can be dynamically controlled in real time by the application of control voltages. The device can be used as a fiber optical gain equalizer or a wavelength selective filtering device which is compact, polarization insensitive, and of low manufacturing costs. The device comprises a stepped transparent substrate, through which the input beam is passed. Within the optical paths of the stepped regions of the substrate, electronically variable phase shifting elements are located, each operative to change the phase of the light passing through its associated step, and thus effectively adding tunability to the height of each step. Planar liquid crystal elements may be used as these elements. The elements may be pixelated, each pixel preferably affecting the phase of the light passing through a fraction of the area of the associated step, such that the interference so can be used to vary the transmission through that step. The pixels thus effectively add tunability to the area of each step. Electronic control of the height and area of each step enables the generation and dynamic control of complex transmission profiles.

Fiber optical gain equalizer

A tunable optical filter is provided that includes an array of independently tunable filter elements. Each of the elements is located along a different optical path that extends between an input and an output port. Optical assemblies for receiving an incident optical signal for providing a filtered optical signal are also provided. In one embodiment, polarization independent spectral filtering can be achieved. Wavelength selectable add/drop multiplexers and demultiplexers, dynamic gain equalizers and attenuators, optical channel blockers and branch filters, switches, and modulators are also provided. Furthermore, methods for constructing and operating filters consistent with this invention are also provided.

Tunable optical filter

A fiber optical attenuator utilizing the cut-off phenomenon for single mode propagation of an optical wave down a single mode fiber, comprising an element such as a pixelated liquid crystal element, capable of spatially changing the phase across the cross section of an input optical signal. Such a spatial phase change is equivalent to a change in the mode structure of the propagating wave. The signal propagating in the single mode output fiber is attenuated in accordance with the extent to which higher order modes are mixed into the low order mode originally present. When the mode is completely transformed to higher order modes, the wave is effectively completely blocked from entering the output single-mode fiber, and the attenuation is high. The level of attenuation is determined by the fraction of the wave which is converted to modes other than the lowest order mode, and is thus controllable by the voltage applied to the pixels of the liquid crystal element.

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Livingston, NJ, United States of America

Gil Cohen