Xtellus, Inc.

Oclaro (new Jersey), Inc.

Finisar Corporation

Yossi Corem

Gil Cohen

SeongWoo Suh

Roey Harel

Boris Frenkel

Yaron Silberberg

Seong Woo Suh

Seongwoo Suh

Haggai Arbell

Johnny Leung

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 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 optical beam processing device with two serially disposed birefringent elements, each element having its own direction of orientation. At least one element is pixelated with electrodes activated by control signals. The directions of orientation of the elements are aligned such that the phase shift imparted to the beam by an unactivated pixel of one element, cancels the phase shift imparted to the beam by the other element, such that the beam traversing that pixel undergoes zero phase shift. An appropriate control signal adds a phase shift to the beam passing through that pixel, so as to generate an overall phase shift through the device for any desired wavelength, which could not be readily achieved by either of the elements alone. The resulting device is thus able to provide switchable phase shifts of exactly zero and pi, for different wavelengths, generally unattainable by a single element device.

Optical devices with cascaded liquid crystal elements

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 single-pole, wavelength selective switch in which the input optical signal is converted to a light beam having a defined polarization, such as S-polarization, with respect to the system plane. The beam is laterally expanded in the system plane, and then spatially dispersed in the same plane as that of the beam expansion, preferably by means of a diffraction grating. The light is directed through a polarization conversion device, preferably a liquid crystal cell, pixelated along the wavelength dispersive direction such that each pixel operates on a separate wavelength. When the appropriate control voltage is applied to a pixel, the polarization of the light signal passing through that pixel is rotated, such as from S to P. The wavelength dispersed beams from the pixels are recombined, and are passed towards another polarizer at the switch output, aligned such that only the selected polarization components are allowed to exit.

Single-pole optical wavelength selector

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, wavelength selective switch, especially for channel blocking applications. The input signal is converted to light beams having predefined polarizations relative to the plane in which optical manipulation of the beam is performed. The beams are then preferably laterally expanded in this system plane only, and then spatially dispersed in the beam expansion plane, preferably by means of a diffraction grating. The light is directed through a polarization rotation device, preferably a liquid crystal cell, pixelated along the wavelength dispersive direction such that each pixel operates on a separate wavelength. When the appropriate control voltage is applied to a pixel, the polarization of the light signal passing through that pixel is rotated. The wavelength dispersed beams from all of the pixels are then recombined, and are passed towards a polarization selective device, aligned such that only selected polarization components are transmitted out of the switch.

A birefringent, electrically-controlled, wavelength selective, pixelated optical phase shifting device, in which the correct drive voltage for a desired phase shift through any pixel can be determined independently of changes in the drive voltage arising from changes in the environmental conditions, generally temperature. This is achieved by mounting a monitor phase shifting element controlled by its own drive voltage, in close proximity to the pixelated phase shifter, such that the monitor element and the phase shifter experience the same environmental condition. A probe optical beam of predefined wavelength is directed through the monitor element, and the transmitted beam measured as a function of the monitor drive voltage. This functional relationship is used to define the environmental condition in which the monitor element and the phase shifter, are situated, and the correct drive voltage for application to any phase shifter pixel can be determined.

Dynamic optical phase shifter compensator

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.

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Beit Shemesh, Israel

Yossi Corem