Abstract: The present invention relates to an isolated polarization beam splitter or combiner, for joining light from different inputs into one common port, and for dividing a beam of light into orthogonal polarizations. In both modes of operation, the splitter/combiner provides isolation preventing transmission of light in a reverse direction. As a splitter, a beam of light is separated through a birefringent material into sub-beams of orthogonal polarization components, and each sub-beam is passed through a non-reciprocal polarization rotator to rotate the polarization so that a reflected beam, or other counter-transmitted light cannot return on the same path through the birefringent material to the source. As a combiner, two separate beams of light are launched with known orthogonal polarizations into a first birefringent material, passed through a non-reciprocal polarization rotator and then combined as orthogonal polarizations into a single output port.

Abstract: A method and circuit is disclosed wherein two waveguides coupled to an optical resonator are further coupled such that beams propagating therein interfere with one another to provide a desired output response. In one embodiment, multiplexed channels of light can be demultiplexed by the device described heretofore, or alternatively, the phase relationship between these two beams can be altered prior to their being combined to provide, for example, a linearized output response useful in applications such as wavelength locking.

Abstract: The traditional solution to monitoring the pump laser power uses the back facet of the pump laser to monitor its power. However, stability and aging issues of the back facet may make it difficult or even impossible to measure the pump power to a high degree of accuracy using this method. Pump lasers often use fiber Bragg gratings to stabilize their wavelength. However, if an in-line optical fiber blazed Bragg grating is used, then the pump power is coupled out of the grating to a detector and monitored. The method of the present invention minimizes components and provides a direct monitoring of fiber coupled power. Alternatively, light coupled out of a WDM is used in a similar manner to monitor the pump power.

Abstract: A method and an apparatus are provided to demultiplex an optical signal having a plurality of channels at a predetermined channel spacing having demultiplexing means with a frequency spacing larger than the predetermined channel spacing for receiving the optical signal and for dividing the optical signal by wavelength into a plurality of wavelength streams broader than the predetermined channel spacing, time domain demultiplexing means for receiving one of the plurality of wavelength streams and for dividing the one of the plurality of wavelength streams into a plurality of time domain demultiplexed wavelength streams, and optical filtering means for demultiplexing one of the plurality of time domain demultiplexed wavelength streams into a single channel. Advantageously, splitting means are provided to split the optical signal into sub-signals before launching them into the demultiplexing means.

Abstract: Bi-directional wavelength interleaving optical isolators provide the ability to pass a first set of optical signals (e.g., ITU even channels) from a first port to a second port, while preventing a second set of optical signals from passing thereto. The bi-directional wavelength interleaving optical isolators also pass the second set of optical signals (e.g., ITU odd channels) from the second port to the first port, while preventing the first set of optical signals from passing thereto. Thus, the bi-directional wavelength interleaving optical isolator can provide bi-directional communications by passing a first set of signals in a first direction and a second set of signals in a second direction.

Abstract: A micromechanical system can include a substrate, an actuator, and an actuated element. In particular, the actuator can include a serpentine arrangement of alternating actuating and opposing segments anchored at a first end thereof to the substrate wherein the actuating segments deflect in response to actuation thereof so that a second end of the serpentine arrangement moves relative to the substrate upon deflection of the actuating segments. The actuated element is attached to the second end of the serpentine arrangement so that the actuated element moves relative to the substrate upon deflection of the actuating segments. Related methods and actuators are also discussed.

Abstract: The invention pertains to a (cascaded) optical switch at least comprising one input path, a number of output paths, one or more switch or splitter stages each comprising one or more optical switches or splitters, and at least one gate for optically disconnecting the output paths from the input path, wherein that gate is located at or near the input path. The cascaded switches according to the present invention are compact exhibit a reduced complexity and an improved insertion loss.

Abstract: The invention pertains to a thermo-optical device comprising a waveguiding structure (1) which comprises at least one input light path (2) and at least two output light paths (3,3′) forming a first y-splitter (4), at least one output light path (3,3′) being provided with primary heating elements (5,5′), characterised in that the output light paths (3,3′) are provided with an additional branch (6) forming a second y-splitter (7), wherein at least one of the branches (6,6′) is provided with a secondary heating element (8,8′). The additional branches (6) may be positioned in the opposite direction, such that in each of the second y-splitters (7) one branch (6′) coincides with one of the output light paths (3,3′) of the first y-splitter (4).

Abstract: Resistor networks, digital potentiometers and microelectromechanical structures that include a plurality of resistors selectable by a plurality of microelectromechanical actuators are provided. More particularly, a thermal relay type of actuator is provided as a switch which may selectively control which of the plurality of resistors is connected. In one particularly advantageous embodiment, the heater for the thermal relay and the plurality of resistors are formed from a common layer of the integrated circuit structure, such as a doped polysilicon layer, which may simplify the manufacturing process. Preferably, a thermal arched beam actuator is utilized in combination with film resistors to provide an integrated circuit device suitable for applications such as digital potentiometers.

Abstract: A microelectromechanical (MEMS) device is provided that includes a microelectronic substrate, a microactuator disposed on the substrate and formed of a single crystalline material, and at least one metallic structure disposed on the substrate adjacent the microactuator such that the metallic structure is on substantially the same plane as the microactuator and is actuated thereby. For example, the MEMS device may be a microrelay. As such, the microrelay may include a pair of metallic structures that are controllably brought into contact by selective actuation of the microactuator. While the MEMS device can include various microactuators, one embodiment of the microactuator is a thermally actuated microactuator which advantageously includes a pair of spaced apart supports disposed on the substrate and at least one arched beam extending therebetween. By heating the at least one arched beam of the microactuator, the arched beams will further arch.

Abstract: This invention discloses to a multi-stage optical isolator having a large centrally disposed birefringent crystal and two smaller crystals sized to separate in a polarization dependent manner into sub-beams and combine light that is separated into sub-beams at an output end thereof. By providing a single large crystal centrally disposed, less alignment is required due to fewer alignment critical components being required. Furthermore, the isolator in accordance with this invention is well suited to high-power applications.

Abstract: The present invention relates to a variable optical filter that can be used to filter an incoming signal, attenuate an incoming signal or in one configuration switch an incoming signal from one path to another. The present invention has found that an accurate and economical variable optical filter can be created by using an elastomeric material having a high coefficient of expansion in cooperation with a means for locally varying the temperature of the elastomeric material as an actuator for moving a reflective surface within the optical filter. The actuator can be operated in a controlled manner for example, to effect a tilt of the reflective surface for switching or attenuating an optical signal, or to vary the resonant wavelengths of a resonant cavity between partially reflective surfaces.

Abstract: The present invention discloses an improved wavelength division multiplexed (WDM) coupler. The WDM coupler includes a WDM filter attached to a first GRIN lens by applying a first heat-curing epoxy of high viscosity. The high viscosity epoxy is applied on peripheral areas of the first GRIN lens away from the optical path of the WDM coupler. The WDM coupler further includes the first GRIN lens with the WDM filter inserted into a first holding tube. The first holding tube is a two-segment holding tube having a segment near the high viscosity epoxy having a slightly greater inside diameter than a second segment away from the high viscosity epoxy. The first GRIN lens with the WDM filter is fixed into the first holding tube by applying a second heat-curing epoxy. The WDM coupler further includes a second holding tube holding a dual fiber pigtail.

Abstract: A MEMS (Micro Electro Mechanical System) variable optical attenuator is provided that is capable of optical attenuation over a full range of optical power. The MEMS variable optical attenuator comprises a microelectronic substrate, a MEMS actuator and an optical shutter. The MEMS variable optical attenuator may also comprise a clamping element capable of locking the optical shutter at a desired attenuation position. The variable light attenuator is capable of attenuating optical beams that have their optical axis running parallel and perpendicular to the substrate. Additionally, the MEMS actuator of the present invention may comprise an array of MEMS actuators capable of supplying the optical shutter with greater displacement distances and, thus a fuller range of optical attenuation. In one embodiment of the invention, the MEMS actuator comprises a thermal arched beam actuator. Additionally, the variable optical attenuator of the present invention may be embodied in a thermal bimorph cantilever structure.

Abstract: Microelectromechanical structures include first and second movable conductive members that extend along and are spaced apart from a microelectronic substrate and are spaced apart from one another, and a movable dielectric link or tether that mechanically links the first and second movable conductive members while electrically isolating the first and second movable conductive members from one another. The movable dielectric link preferably comprises silicon nitride. These microelectromechanical structures can be particularly useful for mechanically coupling structures that are electrically conducting, where it is desired that these structures be coupled in a manner that can reduce and preferably prevent electrical contact or crosstalk. These microelectromechanical structures can be fabricated by forming a sacrificial layer on a microelectronic substrate and forming a dielectric link on the sacrificial layer.

Abstract: Microelectromechanical structures include a microelectronic substrate and spaced apart supports on the microelectronic substrate. A beam extends between the spaced apart supports and expands upon application of heat thereto, to thereby cause displacement of the beam between the spaced apart supports. The application of heat to the beam creates a thermal conduction path from the beam through the spaced apart supports and into the substrate. A thermal isolation structure in the heat conduction path reduces thermal conduction from the beam, through the spaced apart supports and into the substrate, compared to absence of the thermal isolation structure. The thermal isolation structure preferably has lower thermal conductivity than the beam and the supports. The heat that remains in the beam thereby can be increased.

Abstract: A microelectromechanical (MEMS) device is provided that includes a microelectronic substrate and a thermally actuated microactuator and associated components disposed on the substrate and formed as a unitary structure from a single crystalline material, wherein the associated components arc actuated by the microactuator upon thermal actuation thereof. For example, the MEMS device may be a valve. As such, the valve may include at least one valve plate that is controllably brought into engagement with at least one valve opening in the microelectronic substrate by selective actuation of the microactuator. While the MEMS device can include various microactuators, the microactuator advantageously includes a pair of spaced apart supports disposed on the substrate and at least one arched beam extending therebetween.

Abstract: MEMS structures are provided that compensate for ambient temperature changes, process variations, and the like, and can be employed in many applications. These structures include an active microactuator adapted for thermal actuation to move in response to the active alteration of its temperature. The active microactuator may be further adapted to move in response to ambient temperature changes. These structures also include a temperature compensation element, such as a temperature compensation microactuator or frame, adapted to move in response to ambient temperature changes. The active microactuator and the temperature compensation element move cooperatively in response to ambient temperature changes. Thus, a predefined spatial relationship is maintained between the active microactuator and the associated temperature compensation microactuator over a broad range of ambient temperatures absent active alteration of the temperature of the active microactuator.

Abstract: A variable capacitor having low loss and a correspondingly high Q is provided. In addition to a substrate, the variable capacitor includes at least one substrate electrode and a substrate capacitor plate that are disposed upon the substrate and formed of a low electrical resistance material, such as HTS material or a thick metal layer. The variable capacitor also includes a bimorph member extending outwardly from the substrate and over the at least one substrate electrode. The bimorph member includes first and second layers formed of materials having different coefficients of thermal expansion. The first and second layers of the bimorph member define at least one bimorph electrode and a bimorph capacitor plate such that the establishment of a voltage differential between the substrate electrode and the bimorph electrode moves the bimorph member relative to the substrate electrode, thereby altering the interelectrode spacing as well as the distance between the capacitor plates.

Abstract: A broadband optical amplifier that can provide a constant amplifier gain profile, correct for ASE noise, and minimize gain tilt by dynamically controlling different stages of the amplifier through a combination of gain, loss, and power control of each stage depending on input and the desired output level. The multiple stage amplifier has a central control circuit independently controlling each stage, the amplifier comprising a plurality of sequentially coupled stages, each stage being an attenuator stage, a gain setting sub-amplifier stage, or a power level setting stage. The central control circuit determines which stages are actively gain or power controlled.