Abstract: A chassis for fiber optics communication equipment, having a housing with first and second opposing sides, and a back panel cooperating with the housing to provide fore-and-aft slots for cassettes containing optical communication equipment. A remote user interface module for making connections to other items of equipment, and a local user interface module for display of conditions in the cassettes, are situated at opposite sides of the housing, and are both connected to the base by docking stations which allow these modules to be interchanged in position so that either of the first or second sides of the housing may become the front of the chassis; i.e. may be adjacent the local user interface module. This allows the chassis to be reversible so that the cassettes can be removed either from the front or from the rear of the chassis while the local user interface module remains at the front of the chassis.

Abstract: An optical coupler and method of making an optical filter is disclosed wherein a compound lens having two separate movable lenses are disposed between input/output ports and a filter element, such as a dichroic filter element. The filter is tuned during assembly by varying the gap between the movable lenses. Once it is established that optimum coupling is achieved and a desired wavelength response is achieved, the two lenses are fixed in place.

Abstract: The invention disclosed relates to a device for multiplexing/demultiplexing a multi-band DWDM system, providing reduced insertion losses. The device comprises first and second planar waveguides, a light dispersive element having a periodic frequency spectrum, interconnecting the first and second planar waveguides, a plurality of N input waveguides, connected to the first planar waveguide, and a plurality of M output waveguides, connected to the second planar waveguide, wherein the M outputs are each separated by a frequency interval &Dgr;f, the N inputs are each separated by substantially M*&Dgr;f, the free spectral range (FSR) equals substantially N*M*&Dgr;f, where N is an integer greater than 1, and M is an integer equal to or greater than N. In one embodiment of the invention, wherein the telecommunications window is divided into a plurality of sub-bands of M channels, a temperature controller is included to provide individual temperature set points for each sub-band, to reduce wavelength centering errors.

Abstract: A drive towards automation, particularly in the fiber optics industry, has necessitated the use of materials and methods better suited for use by machines. The present invention takes advantage of the magnetic properties of these materials to create a strong magnetic bond between separate elements while they are being connected. Two independently controllable chucks are used to align the elements in accordance with design requirements. After proper alignment, the elements are magnetically attracted together and then permanently fixed using any one of a variety of standards methods, such as welding. In the embodiment of the invention used specifically in the fiber optics industry, the alignment process includes measuring the light transmitted or reflected by the two elements.

Abstract: A micro-optical delay element for a polarization time-division multiplexing scheme is disclosed wherein two light beams are provided to a polarization beam splitter/combiner (PBS/C) in the absence of optical fiber. At least one beam exiting a modulator is collimated and reaches the (PBS/C) unguided as a substantially collimated beam. In this manner the polarization state of the beam is substantially unchanged. This obviates a requirement for polarization controllers.

Abstract: A control system is designed to control an optical cross-connect having a switch core defined by first and second independently movable beam deflectors capable of selectively defining an optical path between a pair of ports of the optical cross-connect. An optical element having optical power is arranged in a propagation path of light beams between the first and second beam deflectors. The control system includes a pilot light source, an optical sensor associated with each beam deflector, and a feedback path. The a pilot light source inserts a pilot light into the switch core colinearly with live traffic. The optical sensor detects a predetermined geometric property of the pilot light emerging from the switch core. This predetermined geometric property is unambiguously associated with an angular position of the associated beam deflector. The feedback path actively controls a position of the associated beam deflector based on the detected geometric property.

Abstract: In an effort to greatly decrease the insertion losses inherent in larger sized M×N optical switches, the present invention deals with minimizing the variation in the optical path lengths of optical beams passing through the switch. To accomplish this goal, the present invention relates to a segmented optical switch comprising four segments, two segments having input ports and two segments having output ports. The segments having output ports are separated from each other, and positioned on adjacent sides of the segments with input ports. Accordingly, the very short optical paths as well as the very long optical paths in the switch are eliminated, thereby minimizing the variation in the optical path lengths. Preferably, the switch is comprised of four identical segments, making manufacturing and supply costs less.

Abstract: A wavelength demultiplexer having a substantially flat output response within its passband is disclosed. The demultiplexer comprises a first wavelength demultiplexer optically coupled to a second wavelength demultiplexer. The first wavelength demultiplexer has a free spectral range approximately equal to channel spacing of the second wavelength demultiplexer thereby providing the substantially flat output response within the passband. The first wavelength demultiplexer is a resonant optical cavity, absent distinct output ports, and light propagating between the first wavelength demultiplexer and the second wavelength deimultiplexer is unguided. The absence of distinct output ports in the first wavelength demultiplexer reduces ripples in the substantially flat output response within the passband. Alternatively, the first wavelength demultiplexer is replaced by an MMI-phasar.

Abstract: A resonant optical cavity is disclosed that has a first partially reflective input end face and a second partially reflective end spaced a predetermined distance apart. The cavity is substantially angle insensitive to a beam of light launched into the cavity at a non-normal angle of incidence to the first input end face along a first line lying on a first plane orthogonal to the first input end face. The second end includes a retroreflector having at two or more partially reflective facts for redirecting light. An optical element having optical power such as a curved mirror or a lens for focusing light is disposed between the retroreflector and the other of the first and second ends. If the optical element having optical power is rotationally symmetrical the optical resonant cavity can be angle insensitive to all input angles. This device is particularly suited for use in the fabrication of an GT or MGT optical device.

Abstract: Optic switches manipulate an optical signal that has been expanded by a collimating lens. Switching is effected by introducing a prism between collimating lenses to redirect the optical signal to an alternative lens. The prism preferably has a cross-section defining a parallelogram, so that the optical signal is reflected twice within the prism to minimize cross-sectional distortion and avoid spectral effects. A circuit provides feedback on the actual position of the relay and prism for fault detection and diagnosis.

Abstract: A conventional interleaver, based on a stack of waveplates, relies on the orientation and the birefringence of the waveplates to differentiate the polarizations of one set of channels from another, so that the one set of channels can be separated from the other. The present invention relates to a virtual waveplate that is used to replace a birefringent waveplate. A virtual waveplate imposes a phase delay between the extraordinary ray and the ordinary ray by separating one from the other and differentiating the actual path lengths taken thereby, before recombining them. An interleaver constructed with the virtual waveplates of the present invention can be substantially a-thermal and potentially chromatic dispersion free.

Abstract: The present invention relates to a multi-stage non-blocking optical switch matrix having failure protection. The optical switch includes failure protection in the form of a capacity to provide an alternative route for any connection, including rearrangeable protection to provide alternative routes for multiple connections, as required, and to permit replacement of any failed submatrix module without service interruption. The present invention provides both internal and external protection from system failure in a multi-stage optical switch matrix by providing interconnected modules in a first external stage. The modules are interconnected by rerouting ports for redirecting signals from an input/output port on one external switch module to another external switch module. Protection is further provided through a center stage having a number of center stage switch modules, fully connected to the external modules, equal to twice the number of input/output ports and rerouting ports on an external module.

Abstract: A system for wavelength locking i.e. for maintaining a frequency of an optical signal to within predetermined limits has means for splitting part of the controlled optical signal into at least three sub-beams of which one is a reference beam and two others are provided to an optical element having a periodic output response and to a filter having a monotonic output response. The three detected outputs are analyzed and processed to determine accurately the wavelength of the optical signal and to produce a correcting signal if it is not within the predetermined limits.

Abstract: An optical device comprises a dispersion element, a reflector, and an angle-to-offset (ATO) element. The angle-to-offset (ATO) element has optical power. The dispersion element is positioned in or near a focal plane of the ATO element and adapted to separate an input wavelength division multiplexed (WDM) light beam received from an input port of the optical device into two or more channel light beams. The reflector is positioned in or near a focal plane of the ATO element and arranged to receive the channel light beams from the dispersion element via the ATO element. The reflector is designed to reflect at least one of the channel light beams toward a respective output port of the optical device. With this arrangement, the dispersion element, reflector and ATO element cooperate to optically demultiplex the input WDM light beam.

Abstract: An electrooptic waveplate for changing the state of polarization of light passing therethrough is disclosed. The waveplate provides a substantially constant birefringence when the principle birefringent axes of the electrooptic waveplate are rotated. The waveplate is an electro-optical material having two principle orthogonal birefringent axes that are rotable when suitable voltages are applied. Two related different voltages are applied along sequential or contiguous regions along the length L of the electo-optical waveplate for providing a controllable and varying electric field along the length L, such that retardance of the waveplate of the length L remains substantially constant while the birefringent axes of the elecrooptic waveplate are rotated by varying the voltages. The two different voltages have a phase relationship or a phase and magnitude relationship therebetween.

Abstract: Automated manufacturing in the fiber optics industry has introduced a series of new problems due to the small size of the parts being assembled and the precise optical alignments required. However, processes requiring the manual assembly of parts using glue are slowly being replaced by automated processes involving the laser welding of metallically encased optical parts. Unfortunately, almost every step in the process causes a small degree of misalignment, which may cause the device to fall below transmission standards. The present invention provides a method of assembling an optical device which includes special steps that involve re-aligning the elements in the optical device after other steps in the method have caused a misalignment. In particular, the method of the present invention includes testing the alignment of the optical elements at several stages throughout the assembly process, and applying addition asymmetric welds to the finished product to improve the transmission results.

Abstract: A 1½×2 optical switch has two GRIN lenses, each lens having two ports on its respective outward end face. The switch has a transmissive wedge-shaped switching element disposed between the GRIN lenses. When the switching element is disposed in the path between the GRIN lenses, a single connection is established between a port of the first GRIN lens and a port of the second GRIN lens, while light is prevented from coupling between the remaining ports.

Abstract: The present invention relates to an optical coupling between an end of an optical fibre and an end of a lens, which provides a reliable joint with a determined spacing and angular orientation. The optical coupling permits movement of the end of the optical fibre relative to the lens in at least two alignment directions. Advantageously, the present invention permits movement of the end of the optical fibre relative to the end of the lens in a direction perpendicular to the optical axis of the lens, before the optical coupling is secured. The optical fibre within an optical fibre tube/ferrule and the lens are secured within separate sleeves and the sleeves bonded together. The end of the optical fibre and the end of the lens are optically aligned before being secured in place relative to each other. Alternatively, the invention provides similar advantages in coupling two lenses to one another via separate sleeves they are contained within.

Abstract: The present invention relates to a micro-electromechanical optical attenuator and a method of operating the same. In prior art attenuators, the attenuation obtained from a deflection angle does not change uniformly over a range of interest. In addition, over a range of interest the required voltage to obtain a desired deflection changes as a nonlinear function. The cause of the poor control of prior art attenuators can be viewed graphically by examining the attenuation as a function of deflection, and the angle of deflection as a function of voltage. These functions combine to produce a very unstable voltage to attenuation response function. The present invention has found that by operating an electrostatic drive of a reflective optical attenuator in order to attain a low loss state with the mirror in a fully deflected position, the drive voltage can be reduced to increase attenuation in a very stable nearly linear attenuation vs. drive voltage response. The non-linearity of the attenuation vs.

Abstract: An optical waveguide device has a hybrid core and a cladding. A first waveguide having a glass core is coupled to a polymer waveguide disposed adjacent and parallel to the first waveguide such that the respective cores are contiguous in a coupling region. The polymer is a thermo-optically active polymer. A heater is provided over the coupling region and the refractive index of the polymer is varied by applying heat to the region. By application of sufficient heat, the refractive index of the polymer can be changed to approach the refractive index of the cladding whereby the device acts as a simple glass waveguide. In the absence of heat, the device acts as a MMI coupler.