Abstract: The present invention is an efficient system and method for cascading optical switches in architectures that enable three dimensional multi-plane optical signal beam steering to be performed with two dimensional steering devices. A plurality of cascaded optical switches form a cascaded multi-plane optical switch fabric and direct an optical signal beam from one of the plurality of optical switches to another of the plurality of optical switches in a different plane. In addition, a multi-plane directional device directs an optical signal beam from a first optical switch stage to a second optical switch stage oriented in a different plane. Furthermore, a fixed incidence corrective device directs an optical signal beam in a shallow angle to an optical switch located in a relatively close proximity on the optical switch fabric and a optical signal beam spread correction device provides for refocusing of spreading optical signal beams and mitigation of signal loss.

Abstract: A polarization beam combiner/splitter (“PBCS”) for combining and splitting multiple channels of light beams simultaneously is disclosed. The PBCS includes a first fiber array, a second fiber array, and an optical core composed of a birefringent or other suitable material. The first fiber array includes a plurality of optical fiber pairs, while the second fiber array includes a corresponding plurality of optical fibers. The optical core is sized to modify light beams from any of the optical fibers of the first or second array. In a beam combining operation, multiple channels of polarized beams are emitted by the optical fiber pairs of the first fiber array and passed through the optical core, which combines the beams into dual-polarized combined light beams. The combined beams exit the optical core and are received by the second array of optical fibers. A similar beam splitting operation can be performed on multiple combined beams.

Abstract: An optical micro-electro-mechanical system (MEMS) switch is disclosed. In a preferred embodiment the optical MEMS switch is used as an M×N optical signal switching system. The optical MEMS switch comprises a plurality of optical waveguides formed on a shuttle for switching optical states wherein the state of the optical switch is changed by a system of drive and latch actuators. The optical MEMS switch utilizes a latching mechanism in association with a thermal drive actuator for aligning the waveguide shuttle. In use the optical MEMS switch may be integrated with other optical components to form planar light circuits (PLCs). When switches and PLCs are integrated together on a silicon chip, compact higher functionality devices, such as Reconfigurable Optical Add-Drop Multiplexers (ROADMs), may be fabricated.

Abstract: A technique is disclosed for performing testing of an optical device under test (DUT). According to a specific embodiment, the DUT includes a plurality of DUT optical input ports and a plurality of DUT optical output ports. The testing may be performed by an optical switching testing system (OSTS) which includes a plurality of OSTS output ports optically connected to a plurality of DUT input ports, and a plurality of OSTS input ports optically connected to a plurality of DUT output ports. Components of the OSTS are configured in order to perform a specific test on the DUT. A first test scenario is configured at the DUT. At least one optical test signal is transmitted to at least one DUT input port. Test results may then be obtained by monitoring at least one DUT output port for the presence or absence of light. The test results are then analyzed for specific characteristics.

Abstract: An optical switching apparatus is provided. Generally, a plurality of optical input switches is provided. A plurality of optical output switches is provided. A plurality of central optical switches connected between the plurality of input switches and plurality of output switches is provided. A plurality of test light sources, where each test light source is connected to an optical input switch, is provided. A first plurality of optical detectors connected to the optical output switches is provided.

Abstract: Techniques and systems for controlling an optical switch array based on local and global optical monitoring and feedback controls. Each optical switch element includes a local optical monitoring mechanism to form a local feedback control to lock the switch element at a desired orientation. The global optical monitoring is used to adjust at least one switch element in the path of the signal beam to maintain an overall alignment.

Abstract: A network healing smart fiber optic switch for fast, automatic switching between multiple paths of an optical transmission line with minimal disruption. The network healing smart fiber optic switch feeds each of multiple fiber optic inputs to a splitter. One of the outputs of the splitters go to an optical switch, which selects the optical signal to send to the output based on a control signal from a controller or analog selection circuit. The other outputs of the splitters go to the analog selection circuit, which outputs a control signal to the optical switch. The analog selection circuit compares the primary optical signal to a selected setpoint to determine the signal's validity. The analog selection circuit routes an alternate, or secondary, optical signal upon failure of the primary optical signal. After the primary signal is restored and valid for a specified period, the analog selection circuit deselects the secondary optical signal and routes the primary optical signal.

Abstract: An optical switch apparatus is disclosed, which applies to the optical communication system or optical system for switching the optical path. The optical switch apparatus utilizes a servomotor rotates a circle mirror unit which two surfaces are coated or deposited a reflecting film and has a plurality of holes. Thereby the optical signals are transmitted from the fibers pass through the holes for transmitting to the others fibers, or the optical signals reflex to the others fibers via the reflecting film for switching the optical path.

Abstract: The present invention provides for a 1×N optical switch having a switching component, an input, and a plurality of outputs formed in a single substrate. The switching component includes a pair of mirrors which are operated such that by changing the position of at least one of the mirrors, the output of the switch changes.

Abstract: A mechanical optical switch provides an active switching mechanism and an active latching mechanism that are both actuated by piezoelectric elements. The switching mechanism includes a switching frame at which fiber ends are attached to be switched along an opposing array of fixed fiber ends. The active latching mechanism provides for a fast switching of the switching mechanism and a reliable holding of the switching positions. The elements of the switching mechanism and the latching mechanism are monolithically fabricated from a wafer. The piezoelectric elements are integrated by bonding. The switch is substantially free of gliding friction, which reduces switching forces and makes the switch highly reliable over an extended lifetime.

Abstract: An optical MEMS devices is imaged to a different location at which a second optical MEMS device is located in a manner that effectively combines the tilt angles of at least one micro mirror of each of the first and second optical devices. The imaging system may reproduce the angle of reflection of the light from the first micro mirror. This may be achieved using a telecentric system, also known as a 4 f system, as the imaging system. The physical size of the arrangement may be reduced by compacting the optical path, e.g., using appropriate conventional mirrors, and/or employing folded arrangements, i.e., arrangements in which there is only one MEMS device stage that does double duty for both input and output through the use of at least one conventional mirror.

Abstract: A device for transmitting optical waves has a structure having at least an optical guide element wherein the structure comprises hollow parts or notches (9, 10) adapted to receive the end parts (13, 14) of an optical fiber (12) such that the fiber spans the surface (11a) of the structure separating the hollow parts and the ends of the optical fiber are respectively optically coupled to optical guide elements (7, 8) of the structure. The invention also concerns a method for making such a device which consists in etching the notch by cutting off the end of the optical micro-guide. The device is useful for producing optical switches.

Abstract: An optical routing apparatus and method that achieves improved optical signal reintegration is disclosed. The optical routing apparatus includes an input port, such as may be provided at the end of an optical fiber. The signal may be routed to one or more of a plurality of output ports, such as may also be provided at the end of an optical fiber, each output port being configured to receive the optical signal. The routing between the input port and the output ports is accomplished with an optical switching arrangement that may shift among multiple distinct optical configurations, each configuration being such as to direct the optical signal to one of the output ports. The ports are positioned such that the input port and at least one of the output ports lie in different parallel planes, each such plane being orthogonal to a path along which the optical signal is provided by the input port or received by one of the output ports.

Abstract: An optical switch including: (a) a light transmissive substrate, and (b) a two-dimensional array, disposed on the light transmissive substrate, the two-dimensional array having rows and columns of reflective shutter assembly elements, each of the reflective shutter assembly elements including: (i) a reflective shutter, and an output diffractive optical element.

Abstract: This invention pertains to a device and method for making same. The device includes a substrate suitable for supporting pathways for optical signals; separate pathways disposed on the substrate suitable for propagating optical signals, the pathways including an input and an output optical pathway; and a reflective surface in operative contact with the input and output pathways for receiving an optical signal from the input pathway and reflecting the optical signal into the output pathway.

Abstract: An optical device for rerouting and modifying an optical signal that uses a double pass through a liquid crystal modulator is disclosed. The optical device includes a first polarizer for providing polarized light, a liquid crystal modulator for selectively modifying the polarized light, a second polarizer for analyzing the light passed through the liquid crystal modulator, and a reflector for reflecting the analyzed light back through the second polarizer, the liquid crystal modulator, and the first polarizer. This arrangement provides a double pass through the liquid crystal modulator, thus significantly improving the attainable extinction ratio.

Abstract: An assembly and a method for accurately aligning optical fibers in an optical switch are described. An optical switch assembly is described having a pair of optical arrays mounted on a mounting apparatus. The mounting apparatus may include a base structure with either integral rails or affixed fibers. Alternatively, the mounting apparatus may include a base structure with grooves and a plurality of spheres in the grooves. An alternative arrangement includes a base structure with some grooves extending transverse to other grooves and mounting structures in each groove. One of the optical arrays is rendered immobile while the other array is freely movable on the mounting apparatus. Switching is provided by moving the movable fiber array relative to the fixed fiber array.

Abstract: An optical device includes: a first polarization beam splitter (PBS); a first set of optical rotators optically coupled to the first PBS; a second PBS optically coupled to the first set of optical rotators; a first reflection interferometer (RI) optically coupled to the second PBS; a second RI optically coupled to the first PBS; a second set of optical rotators optically coupled to the second PBS; a third PBS optically coupled to the second set of optical rotators; and a third RI optically coupled to the third PBS. Preferably, the optical device is an Optical Add/Drop Multiplexer and may further comprise an Input Port optically coupled to the first PBS, an Output Port optically coupled to the second PBS, and an Add Port optically coupled to the third PBS.

Abstract: Novel light switches and attenuators are disclosed. In one form of the invention, a novel 1×2 switch is formed by positioning a moveable cantilever mirror having an opening intermediate three fiberoptic lines. In another form of the invention, a novel n×n switch is formed by positioning a moveable cantilever mirror having n openings intermediate n sets of three fiberoptic lines. In still another form of the invention, a novel variable optical attenuator is formed by incrementally positioning a moveable cantilever mirror having an opening intermediate a set of three fiberoptic lines.

Abstract: The present invention provides an optical switch. The switch includes a substrate and a first waveguide holding member. The switch also includes a second waveguide holding member disposed over the substrate and movable relative to the first waveguide holding member to provide a switching function. A movement guiding member is provided for guiding the movement of the second waveguide holding member. A registration element is disposed at the movement guiding member for positioning the second waveguide holding member at a selected location relative to the first waveguide holding member. The selected location is one that provides alignment between a selected waveguide of the first waveguide holding member and a selected waveguide of the second waveguide holding member.

Abstract: There is disclosed an optical switch consisting of a support substrate, a movable raw optical fiber, a fixed raw optical fiber, a magnetic member for the movable raw optical fiber, and a leaf spring. The fibers are disposed in a V-shaped groove formed in the substrate. The magnetic member is actuated by an electromagnet disposed above the substrate. The leaf spring pushes the movable raw optical fiber into the V-shaped groove. The structure of the switch is relatively simple. Since the movable raw optical fiber is pushed using the leaf spring, the switch is less affected by the assembly accuracy than conventional. It is easy to make adjustments during assembly. Consequently, high-performance, low-cost, optical switch that can be mass-produced can be offered.

Abstract: An optical transmission device which reduces optical noise in an optical transmission system. The optical transmission device includes a core light amplifying unit, and a first buffer light amplifying unit for amplifying a first signal light from a first transmission path and an amplified second signal light from the core light amplifying unit. The first buffer light amplifying unit supplies the core light amplifying unit with the first signal light, and supplies the first transmission path with the amplified second signal light. Also provided is a second buffer light amplifying unit for amplifying a second signal light from a second transmission path and an amplified first signal light from the core light amplifying unit. The second buffer light amplifying unit supplies the core light amplifying unit with the second signal light, and supplies the second transmission path with the amplified first signal light.

Abstract: An optical device that can be used in a range of telecommunications applications including optical multiplexers/demultiplexers and optical routers. The optical device splits and combines optical signals of frequency division multiplexed optical communication channels that are evenly spaced apart in frequency from one another. The optical device includes a first filter and a second filter. The first filter splits and combines odd and even channels depending on the propagation direction of the optical signal. The first filter exhibits complementary phase retardations corresponding with odd integer multiples of half a wavelength for each center wavelength associated with a selected one of the odd and even set of channels and with integer multiples of a full wavelength of each center wavelength associated with a remaining one of the odd set and the even set.

Abstract: An optical fiber switch having two coupled fiber arrays which move in a transverse direction to provide switching action. Each array has a front face and the front faces are nearly in contact. Optical fiber ends are located at the front faces. The front faces of the fiber arrays have transverse grooves in which rolling spheres are disposed. The fiber arrays move by rolling on the spheres. The spheres provide for smooth transverse motion and a fixed distance between optical fiber arrays. The spheres and front face grooves also provide for alignment between the optical fibers.

Abstract: An optical switch switches the light path between collimate lenses optically coupled to the ends of corresponding optical fibers by the advancing and retracting movements of a prism. The prism comprises an electromagnetic driver having an armature arranged to hold the prism, a coil block for driving the movement of the armature by use of magnetic actions and a leaf spring. The leaf spring mainly includes four parallelly extending spring strips fixedly joined at one end to a body and at another end to the armature to thus spatially hold the armature and the prism for linear movement. The electromagnetic driver and the prism are disposed next to each other along the moving direction of the armature. The armature and the prism can be linearly moved at a right angle to the light path between the lenses when the optical switch is in action. This allows the prism to be linearly moved, and the device can be minimized in overall size.

Abstract: An optical switch includes a first wavedguide holding member and a second waveguide holding member disposed on a substrate. The first waveguide holding member moves relative to the second waveguide holding member. A movement guiding member guides the motion of the first waveguide holding member and the substrate. Advantageously, the first waveguide holding member moves transversely relative to the second waveguide holding member. The traverse motion enables selective coupling between a waveguide in the first waveguide holding member and a waveguide in the second holding member. Through this transverse motion of the second waveguide holding member, an optical switching action may be implemented.

Abstract: This application describes an optical switching method for selectively directing an input beam to at least one of two output channels. The input beam impinges on a polarizing beam splitting surface, splitting the input beam into two beam components of different polarizations propagating along different optical paths. These beam components then pass through a controllable polarization rotating medium which selectively affects the polarization of each of the beam components. The beam components are then directed back onto the polarizing beam splitting surface again, producing at least one output beam which propagates toward at least one selected output channel, depending on the state of the medium. The polarizing beam splitting surface is fabricated on a block of the controllable polarization rotating medium, and the input beam also passes through the medium before being split into two beam components by the polarizing beam splitting surface.

Abstract: A monolithic single pass expanded beam mode active optical device includes: a substrate; a waveguide layer coupled to the top surface of the substrate; a semiconductor layer coupled to the waveguide layer; first and second electrodes for receiving an electric signal coupled to the substrate and the semiconductor layer, respectively. The waveguide layer includes a plurality of sublayers, forming a quantum well structure, which is responsive to the electric signal. The waveguide layer has three sections, two expansion/contraction sections and an active section, which extends between and adjacent to the two expansion/contraction sections. The thickness of at least one of the plurality of sublayers varies within the expansion/contraction portions of the quantum well structure. Possible interactions of the active region with the light include: absorption in the case of an electro-absorptive modulator and optical gain.

Abstract: A method of monitoring fiber optic circuits. Included is manipulating a first switch between a first state, with first connection points optically linked along a first optical signal pathway and second connection points optically linked along a second optical signal pathway, and a second loopback state, with the first and second connection points of a first pair of connection locations in communication along a path along a portion of the first and second optical signal pathways. With the first switch in the first state, a third pair of connection locations are linked to the first optical pathway and the optical throughout observed. The third pair of connection locations are then linked to the second optical pathway and the optical throughout observed. These steps are repeated as long as the first and second optical pathways transmit the optical throughout normally.

Abstract: The switching method is constituted with a novel nonblocking routing optical crossbar network system. It includes two parts: one is a routing fan-out unit which provides N parallel optical channels for each of M input light beams, and the other is a routing combination unit in which M parallel optical channels that have the same output port, are routing combined into one optical parallel channel of N parallel output channels by the routing fan-in network. According to the method of the present invention, the optical module of M×N (M=2m, N=2n, m and n are nature numbers) routing matrix switching can be developed.

Abstract: A device and method for detecting rotational drift of mirror elements in a MEMS tilt mirror array used in an optical crossconnect. The optical crossconnect directs optical signals from an input fiber to an output fiber along an optical path by rotatably positioning mirror elements in desired positions. A monitoring device disposed outside of the optical path is used to obtain images of the MEMS array or to transmit and receive a test signal through the crossconnect for detecting the presence of mirror element drift.

Abstract: An apparatus comprising a first plate having a plurality of v-shaped grooves to hold a set of optical fibers and a second plate having a v-shaped groove to hold a secondary optical fiber is disclosed. In one embodiment, the second plate being movable relative to the first plate, so that the secondary optical fiber can be selectively coupled to one of the optical fibers of the first set of optical fibers.

Abstract: A method and apparatus for measuring optical power or insertion loss within an optical cross-connect system utilizing a plurality of parallel light beams sampled at switch fabric input and output portions via imaging devices.

Abstract: A first waveguide holding member has a first transverse surface region and a first optical waveguide having an end terminating at the first transverse surface region. A second waveguide holding member has a second transverse surface region which confronts the first transverse surface region of the first waveguide holding member and a second optical waveguide having an end terminating at the second transverse surface region. A guide member is operatively coupled to the first and second waveguide holding members and guides the first waveguide holding member in a transverse direction relative to the second waveguide holding member so as to selectively optically couple and decouple the ends of the first and second optical waveguides.

Abstract: This invention provides a transparent, paramagnetic polymer composition in which a polymer is complexed with sufficient rare earth ions, particularly ions selected from ions in the group of elements 64-69, to provide a polymer with a magnetic mass susceptibility greater than 20×10−6 emu/g measured at 298° K. This invention provides optically responsive devices that employ these transparent, paramagnetic polymers as an element that is responsive to a magnetic field and a means for providing magnetic field. This invention provides transparent labels or markings employing these transparent, paramagnetic polymers.

Abstract: An optical switching assembly comprised of a substrate, a first plurality of waveguides in a first plane in the substrate, a second plurality of waveguides in a second plane parallel to said first plane in the substrate, the optical signals being selectively transferable from one substrate to the other. The second waveguides cross the first waveguides at an angle and the first waveguides each have a segment extending generally parallel to a segment of the second waveguides at the crossing. Controllable coupling material is disposed between the segments of the waveguides at the crossing and a control circuit is employed for selectively changing the index of refraction of the coupling material by electrical or thermal means.

Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer includes an arrayed waveguide connected to at least one first optical waveguide via a first slab waveguide, a plurality of second optical waveguides connected to the arrayed waveguide via a second slab waveguide. At least one multi-mode waveguide has a first end portion and a second end portion having a second width larger than a first width of the first end portion. The first end portion of each of the at least one multi-mode waveguide is connected to each of the at least one first optical waveguide. The second end portion of each of the at least one multi-mode waveguide is connected to the first slab waveguide. A width of the at least one multi-mode waveguide increases from the first end portion toward the second end portion and is configured to realize multi-mode.

Abstract: An improved thermally tunable system is provided. The improved thermally tunable system includes a thermally tunable apparatus including a first portion and a second portion, a heater configured to thermally tune the apparatus, and a heat sink disposed adjacent to the apparatus, wherein thermal flow is controlled to pass from the heater through the first portion of the apparatus, and then through the second portion into the heat sink, such that a temperature of the second portion remains substantially constant or within a predetermined range. A thermally conductive material is provided between the second portion of the apparatus and the heat sink. A thermally insulating material is provided between the first portion of the apparatus and the heat sink.

Abstract: A data communication system comprising a plurality of fiber optic cables and a fiber optic switching system, comprising: a support structure for securing light emitting/light receiving ends of the plurality of fiber optic cables in predetermined positions; and, means for re-directing light emitted from the light emitting/light receiving end of one of the fiber optic cables to the light emitting/light receiving ends of one, or more than one, of a plurality of the plurality of fiber optic cables. The re-directing means includes means for collimating and directing the light emitted from the end of one of the cables as a beam propagating along a predetermined direction and for re-directing the beam towards the end of another one of the cables selectively in accordance with an electrical signal. More particularly, the re-directing means includes electro-optical phase shifting medium, preferably liquid crystal molecules.

Abstract: Two N-channel deflector modules, both located in the same layer or plane of an assembly, direct polarized beams toward a polarization beam splitter. A half wave plate is interposed between one of the deflector modules and the polarization beam splitter. The polarization beam splitter combines the two beams into a single output beam, without loss of optical power, comprising 2N channels, each of which can carry a unique data stream. In alternate embodiments the group of two deflector modules and a polarization beam splitter can be stacked, optionally in combination with layers comprising a single deflector module and polarization beam splitter or mirror.

Abstract: A mechanical optical switch provides an active switching mechanism and an active latching mechanism that are both actuated by piezoelectric elements. The switching mechanism includes a switching frame at which fiber ends are attached to be switched along an opposing array of fixed fiber ends. The active latching mechanism provides for a fast switching of the switching mechanism and a reliable holding of the switching positions. The elements of the switching mechanism and the latching mechanism are monolithically fabricated from a wafer. The piezoelectric elements are integrated by bonding. The switch is substantially free of gliding friction, which reduces switching forces and makes the switch highly reliable over an extended lifetime.

Abstract: A spatial light modulator (SLM) has electrically controllable microelectromechanical reflectors arranged in a chain-like manner along an axis such that an optical beam propagates by reflection from an input down the chain to an output. Each reflector can be moved to a selected one of a number of discrete switching positions. The position determines the angle at which the beam is reflected toward the next reflector in the chain. The combination of positions in which the reflectors are oriented is determinative of the angle at which the signal exits the output. The SLM can be included in a switch. An SLM in the input section of the switch can be adjusted to direct the beam such that it impinges upon a selected switch output. Multiple SLMs can be included in an array to provide a cross-connect or crossbar switch.

Abstract: An optical device that can be used in a range of telecommunications applications including optical multiplexers/demultiplexers and optical routers. The optical device splits and combines optical signals of frequency division multiplexed optical communication channels which are evenly spaced apart in frequency from one another. The optical device includes a first filter and a second filter. The first filter splits and combines odd and even channels depending on the propagation direction of the optical signal. The first filter exhibits complementary phase retardations corresponding with odd integer multiples of half a wavelength for each center wavelength associated with a selected one of the odd and even set of channels and with integer multiples of a full wavelength for each center wavelength associated with a remaining one of the odd set and the even set.

Abstract: An apparatus and method for switching one or more optical paths comprises one or more inputs and one or more outputs arranged with one or more free-space optical paths formed therebetween, and one or more prisms movable to the free-space optical paths being inserted into or removed from the free-space optical paths to control the propagation paths of one or more light beams between the inputs and outputs. When the prism is inserted into the free-space optical path, a switched optical path between the inputs and outputs is formed to direct the light beam with two refraction and one total reflection by the prism. When the prism is removed from the free-space optical path, the light beam propagates along the free-space optical path.

Abstract: An optical transmission device which reduces optical noise in an optical transmission system. The optical transmission device includes a core light amplifying unit and a first buffer light amplifying unit for amplifying a first signal light from a first transmission path and an amplified second signal light from the core light amplifying unit. The first buffer light amplifying unit supplies the core light amplifying unit with the first signal light, and supplies the first transmission path with the amplified second signal light. Also provided is a second buffer light amplifying unit for amplifying a second signal light from a second transmission path and an amplified first signal light from the core light amplifying unit. The second buffer light amplifying unit supplies the core light amplifying unit with the second signal light, and supplies the second transmission path with the amplified first signal light.

Abstract: A mechanical optical switch includes a port, a first lens element, a free beam path, and a beam guiding element. The port is adapted to receive a first group of optical fibers. The first lens element has an optical axis and is positioned in front of the first group of optical fibers. The free beam path couples light beams from a second group of optical fibers to the first lens element such that the light beams are coupled to the first group of optical fibers in a first coupling arrangement. The beam guiding element is configured to move into and out of the free beam path. Moving the beam guiding element into the free beam path shifts the light beams by an offset and rotates the light beams by an angle such that the light beams propagate to the first lens element and are coupled into the first group of optical fibers in a second coupling arrangement.

Abstract: A switching device that receives a plurality of input signals and provides a plurality of output signals has switches arranged in a two- or three-dimensional array configurations. At least two of the switches, which are preferably microelectromechanical or MEMS switches, reside on distinct physical substrate layers in the switching device, and at least one of the signals travels through a penetrable zone of one of the physical substrate layers. Three dimensional switching device blocks can be conveniently arranged in a Clos configuration or other switching configurations to reduce blocking and avoid rearrangement. The switching devices may be used to switch optical signals and may include mirrors as switching elements.

Abstract: An optical switch and router configuration employing at least one material having radiation induced color centers to produce a change in the reflective index of the material. The material will reflect an input optical signal when the material is illuminated by a control optical signal source and the color centers are induced. An erase beam can be used to remove the color centers, therefore returning the material to a transmittive state such that an input optical signal can be transmitted through it, or the color centers can be allowed to dissipate after their naturally short lifetime.

Abstract: The present invention aims at providing an optical switch changeover controlling method, an optical node device and an optical switch system, capable of avoiding an interruption in an optical output power when changing over an optical path making use of a spatial optical switch arranged with a plurality of optical switch elements. To this end, the optical switch changeover controlling method according to the present invention enables an uninterrupted changeover of an optical path by conducting a reconnection of the optical path after establishing a state where the optical path before the changeover and the optical path after the changeover are simultaneously set concerning the spatial optical switch within the optical node device, when conducting a changeover of the optical path so as to transmit a client optical signal having been transmitted through a working ray path to a protective ray path such as in a case that a fault occurs in the working ray path.

Abstract: An optical switch comprises an optical input (902) and an optical output (904), the switch further comprising a wavelength selective switch element (912) for directing light of a selected wavelength between the input (902) and the optical output (904), wherein the switch element is tuneable to a plurality of different wavelengths. By having tuneable switch elements, the switch can be made having fewer elements and therefore more compact.