Abstract: An optical spectral filtering device and associated method for selectively directing a portion of a wavelength multiplexed input signal, entering through an optical fiber, into one or more output signals provided to one or more optical fibers and/or electronic outputs. The optical filtering is accomplished using free-space diffractive wavelength demultiplexing optics combined with a fixed (permanent) patterned structure located in the spectrally dispersed image plane. The structure can block or direct a selected spectral portion of the optical signal to one or more separate outputs, such as an optical fiber or power detector. A single active element in the optical path is used to spatially shift, or steer, the entire input spectrum at the dispersed spectral image plane, to control the portion of the input spectrum illuminating specific features on the permanent patterned structure.

Abstract: We describe an optical spectral filtering device and associated method for selectively directing a portion of a wavelength multiplexed input signal, entering through an optical fiber, into one or more output signals provided to one or more optical fibers and/or electronic outputs. The optical filtering is accomplished using free-space diffractive wavelength demultiplexing optics combined with a fixed (permanent) patterned structure located in the spectrally dispersed image plane. The structure can block or direct a selected spectral portion of the optical signal to one or more separate outputs, such as an optical fiber or power detector. A single active element in the optical path is used to spatially shift, or steer, the entire input spectrum at the dispersed spectral image plane, to control the portion of the input spectrum illuminating specific features on the permanent patterned structure.

Abstract: Methods and apparatus for spatially-shifting and multiplexing optical signals for transmission in a wavelength division multiplexed or dense wavelength division multiplexed optical communication system linearly disperse the optical signals and then spatially, laterally shift the signals. The spatially shifted, dispersed signals are thereafter re-imaged to remove the linear dispersion so that the spatially shifted signals can then be transmitted through the optical communication system. The spatially-shifted, multiplexed signals have a flat passband with sharp transition points so that the transmitted signals are routed through the optical communication system with low loss and high integrity.

Abstract: In an all optical switch an imaging system is interposed between the micro lens array and the moveable micro mirrors of a MEMS device to which, or from which, the light beams are directed. This causes an image of the micro lens array to be formed at the MEMS device, or vice-versa, thus effectively eliminating the distance between the micro lens array and the MEMS device. The imaging system may be a telecentric system. The 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. The overall system is arranged to account for any inversions introduced.

Abstract: In accordance with the invention, a electromechanical optical modulator comprising an optical membrane, a substrate and Fabry-Perot air gap between them is provided with an improved structure for controlling light transmitted into the substrate. Specifically, an etched and coated cavity is formed in the backwall of the substrate underlying the air gap to receive transmitted light and redirect it onto controllable paths within the substrate. Advantageously the substrate is silicon, and the cavity is produced by anisotropic etching.

Abstract: Method and apparatus are disclosed for an optoelectronic network interface device allowing reconfiguration of ports in a Local Area Network (LAN). More particularly, the optoelectronic interface device is integrated to include optical ports for communicating with a network, electronic circuits for providing an interface to end-users and a controllable electronic switch between the optical ports and electronic circuits. In response to a control signal, the switch dynamically reconfigures the connection between selected optical ports and selected electronic circuits.

Abstract: A free space multiport wavelength router for directing channels of a received WDM optic signal to a plurality of output ports. The inventive router includes a lens which receives an incoming WDM signal and focuses the signal on a grating for angular displacement, as a function of wavelength, of the individual channels in the WDM signal. The angularly displaced channels are then collimated by the lens and provided to an array of optical elements. The array is oriented relative to the lens so that each element in the array receives and imparts an orthogonal displacement to a corresponding channel relative to the dispersement direction provided by the grating. The othogonally-dispersed channels are then reflected back to the grating and are output to select output optic fibers.

Abstract: In accordance with the invention, a WDM optical communication system includes a new tunable multi-channel dispersion compensating filter having low loss, low polarization dependence and capable of compensating many channels over a large wavelength range. In essence, the filter comprises an optical cavity with a near 100% reflector on one side and a variable partial reflector on the other side. The device acts as a tunable all-pass filter.

Abstract: In accordance with the invention, a WDM optical communication system includes a new tunable multi-channel dispersion compensating filter having low loss, low polarization dependence and capable of compensating many channels over a large wavelength range. In essence, the filter comprises an optical cavity with a near 100% reflector on one side and a variable partial reflector on the other side. The device acts as a tunable all-pass filter.

Abstract: An optical local area network uses modified remote network interface cards (NICs) to provide an optical carrier signal for signaling use by a centralized optoelectronic switch unit. The NIC optical transceiver is modified so that instead of being normally “off” during the standby mode, the data signal is logically inverted to be “on.” Light from each NIC is used to provide optical power for a corresponding optical modulator on the switch unit.

Abstract: In an all optical switch an imaging system is interposed between the micro lens array and the moveable micro mirrors of a MEMS device to which, or from which, the light beams are directed. This causes an image of the micro lens array to be formed at the MEMS device, or vice-versa, thus effectively eliminating the distance between the micro lens array and the MEMS device. The imaging system may be a telecentric system. The 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. The overall system is arranged to account for any inversions introduced.

Abstract: Feedback instabilities arising from interactions between automatic control loops at the amplifier nodes of an optical network are eliminated by restricting operation to a single amplifier node at a time. Amplifier node activation is accomplished using a global control signal which is sequentially passed from an upstream node through all of the nodes of the system. By controlling the state of the global control signal, an upstream node has operational priority over downstream nodes.

Abstract: A method and apparatus for multiplexing and demultiplexing light signals of multiple wavelengths using two canceling dispersion stages with a stage between them which transforms the angular positions of the beams, the lateral positions of the beams, or both the angular and lateral positions of the beams. Light of multiple wavelengths is introduced through an input waveguide. The light then enters the first stage of the invention which disperses the signal. The dispersed signals then enter a second stage in which they are transformed. The transformed signals then enter a third stage where they are subject to the inverse of the dispersion performed in the first stage. In other words, if the third stage were placed immediately after the first stage, the third stage would nullify the dispersion of the first stage. However, adding the intervening transformation step results in only the simple linear dispersion being canceled in the system while the transformed part of the dispersion is retained.

Abstract: An optomechanical platform that provides both precise alignment and ready manufacture of optical and optomechanical components. A simplified embodiment of the invention includes a substantially symmetric cylindrical tube with an optical device at one end of the tube, a grating at another, opposite end of the tube and optics disposed between. optomechanical/optoelectronic device that is particularly well suited to WDM and imaging applications. Included is an integrated optomechanical/optoelctronic device particularly well suited to imaging and Wavelength-Division-Multiplexed (WDM) applications.

Abstract: A method and assembly for optically connecting a first grouping of optical fibers with a second grouping of optical fibers. To form the optical connection, the optical fibers in the first grouping and the second grouping are set into two separate arrays. A plurality of collimating elements are positioned proximate both arrays. The collimating elements correspond in both number and orientation to the optical fibers. As a result, any light signal emanating from either the first array or the second array will pass through a collimating element and will become substantially collimated. The first array and the second array are oriented with respect to one another so that each collimated element is at least partially aligned with a collimating element from the opposing array. Accordingly, light emitted from one fiber element in one array will be focused on an optical element in the opposing array without the optical fibers being precisely aligned.

Abstract: A router combines free-space and guided wave optics to drastically increase the number of channels used in WDM transmission systems. The two-stage router uses the partial demultiplexing characteristic of an arrayed waveguide router (AWR) combined with a free-space optical router to fully demultiplex an input WDM signal. The two-stage router can be used to obtain output wavelength signals in either one- or two-dimensional arrays.

Abstract: A class of opto-electronic mechanical devices that include a planar optical waveguide having a cladding in which there is carried an evanescent electric field by a light beam traveling along the waveguide and a mechanical micro-element controllably coupled into the evanescent field for varying locally the properties of the waveguide in a wavelength dependent fashion. The devices described include optical switches and WDM add/drop apparatus.

Abstract: Automatic bias setting circuits for multiple quantum well (MQW) diodes and optical modulators generally are described. Both digital and analog circuits are provided and techniques for utilizing such circuits for monitoring and controlling optical modulator signal quality are disclosed. In one approach, a desired modulation voltage range is determined. A bias voltage is stepped from a first predetermined voltage up to a second predetermined voltage. A maximum differential photocurrent is determined and the bias voltage corresponding to that photocurrent is then employed so that optimal optical modulator signal quality is achieved. An advantageous application of this technique is in wavelength division multiplexed (WDM) systems in which different optical modulators are operating at different wavelengths. In such a system, a different voltage bias will typically be determined for each optical modulator.

Abstract: An optical assembly for detecting an optical signal from a signal source in systems where the intensity of the optical signal may surpass the operational range of the optical detector being used. The optical assembly includes an optical detector for converting the optical input signal into a corresponding electrical output signal. The optical detector has a set operational range of input signal intensities. An attenuator is disposed between the optical detector and the signal source. The attenuator is capable of reducing the signal intensity of the optical signal if required so that the optical signal falls within the operational range of the optical detector. A controller is electronically coupled to both the optical detector and the attenuator. The controller controls the attenuator as a function of the output signal of the optical detector, wherein the attenuator attenuates the optical signal to fall within the operational range of the optical detector.

Abstract: A free-space N by M, where N and M>1, optical signal switch (OXC) requires only transmitter beam steering for controlling to which receiver an optical signal from a transmitter is directed. In a preferred embodiment the transmitters handle single mode optical signals and the receivers handle multimode optical signals. The OXC may optionally include a fixed optical unit implemented using either a single fixed shared lens or a plurality of M optical elements for further directing each of the M optical signals to their respective receivers.