Abstract: An apparatus capable of operating as an interleaver, a deinterleaver, a filter, or some combination thereof is described. An optical device that can be configured to multiple different optical components. In one embodiment, the optical device can be configured to operate as a single double-pass interlayer/deinterleaver, as two single-pass interleaver/deinterleavers, or as one or more filters. In one embodiment, the optical device has ports on two or more planes and a birefringent element that occupies the two or more planes. Connections between the two or more planes can be made by walk-off crystals internal to the optical device or between ports by connections that are external to the optical device to configure the optical device.

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 method and apparatus for optically isolating multiple core optical fibers while at the same time substantially reducing polarization mode dispersion, is disclosed. A multiple core fiber is optically coupled to optical birefringent elements, reciprocal and non-reciprocal rotators, and through a lens assembly to a multiple core optical fiber output.

Abstract: Interleaver/deinterleavers for combining/separating optical channels. An interleaver/deinterleaver is “folded” when an optical signal follows an optical path that passes through a birefringent element multiple times. Double-pass refers to optical signals following a (folded) path through the birefringent element twice. Multi-pass refers to optical signals following a (folded) path through the birefringent element multiple times. When operating as a deinterleaver, the interleaver/deinterleaver separates an optical signal (e.g., WDM signal) into subsets of optical signals (e.g., even and odd ITU channels). When operating as an interleaver, the interleaver/deinterleaver mixes subsets of optical signals into a multiplexed optical signal. The interleaver/deinterleaver can be used to increase the bandwidth of an optical network. For example, the interleaver/deinterleaver can be used to interface components designed for a first channel spacing (e.g.

Abstract: A method and device is disclosed for dispersion compensation of an optical signal having periodic dispersion within a multi-channels system. For example interleaved optical channels often exhibit dispersion having a characteristic that is repeated in adjacent channels. By providing a periodic device that allows for polarization dependent routing of an interleaved signal to allow for multiple passes of said signal through a multi-cavity GT etalon, having a free-spectral range that corresponds to the channel spacing, the dispersion in the interleaved signal can be lessened and practically obviated or balanced to a desired level. This invention provides a device and method to achieve that end.

Abstract: An optical isolator coupled to a thermally expanded multiple core fiber. The thermally expanded multiple core fiber having at least one input core and one output core. The optical isolator to propagate light from an input core to an output core, while inhibiting the propagation of light from an output core to an input core of the thermally expanded multiple core fiber. The fiber cores having expanded mode field diameters that may facilitate coupling to the optical isolator and reduce component size in the optical isolator.

Abstract: The isolator core having a walk-off crystal, a non-reciprocal rotator coupled to the walk-off crystal, and a reciprocal rotator coupled to the walk-off crystal.

Abstract: The invention provides an optical attenuator having a pair of substantially parallel mirrors that attenuate an optical signal based, at least in part, on the rotation angle of the mirrors. When the pair or mirrors is in a predetermined position, an input optical signal is directed from an input port to an output port with a minimum insertion loss. As the pair of mirrors is rotated, the optical signal is shifted parallelly, which provides increased insertion loss and an attenuated signal at the output port. The pair of mirrors can be rotated, for example, with a stepper motor, or other device.

Abstract: A method of assembling an optical device for coupling optical fibers to a corresponding number of input/output ports of a stack of optical elements includes utilizing at least one controllable multi-state optical element to selectively switch the optical coupling among the ports. The controllable multi-state element is one element within a stack of polarization-manipulating elements having a configuration that allows the condition of the multi-state element or elements to dictate the optical coupling among the ports. In the preferred embodiment, the multi-state element is a Faraday rotator. The method may be used in either or both of a quality control application or a fiber-to-port alignment application. In the quality control operation, the stack of polarization-manipulating elements is tested to verify proper operation with respect to separating and selectively recombining polarization components of input beams.

Abstract: A multiple port reflection based circulator using a thermally expanded multiple core fiber. The circulator includes optical components to separate, rotate, and combine orthogonally polarized components of light in order to propagate light in one direction among consecutive cores of the fiber. The first and last cores of the fiber also being consecutive cores. The thermally expanded multiple core fiber enabling coupling to the circulator without the use of lenses.

Abstract: An optical fiber having a thermally expanded multiple core section. One such multiple core section may be fabricated by fusing together non-etched multiple fiber claddings resulting in the multiple cores having expanded mode fields that are positioned in close proximity to each other in a common cladding, without signal coupling between the cores. The close proximity of the cores having expanded mode fields may allow for tighter alignment of light waves propagated from one core to other cores.

Abstract: An optical nonreciprocal apparatus, preferably an optical isolator, and a method of isolating propagation of light signals from multiple input optical fibers to multiple output optical fibers utilize compact isolator chips formed by a nonreciprocal rotator assembly that is sandwiched between two walk-off crystals. The nonreciprocal rotator assembly provides 90.degree. rotation of polarization components of forward propagating light beams, while providing 0.degree. rotation for rearward propagating light beams. In one embodiment, the optical nonreciprocal apparatus includes two isolator chips between an array of lenses to provide two-stage optical isolator. Preferably, the walk-off crystals in the second isolator chip provide displacement of aligned polarization components of forward propagating light beams in a direction that is perpendicular to the walk-off directions of the walk-off crystals in the first isolator chip.

Abstract: A method of fabricating split optical elements includes fixing a number of optical members in a side-by-side arrangement such that abutting optical members have different optical characteristics with respect to manipulating polarization components of light. In the preferred embodiment, the optical members are fixed to a transparent substrate by an optically transparent epoxy and the optical members are walk-off crystals having oppositely directed walk-off directions. The arrangement of optical members is segmented to form discrete optical elements comprising first and second portions supported on a segment of the transparent substrate. The first and second portions exhibit different optical characteristics with respect to manipulating polarization components. In one embodiment, the arrangement is segmented by dicing the optical members in a lengthwise direction in a first series of cuts and dicing the optical members in a widthwise direction in a second series of cuts.

Abstract: A miniature three-port optical circulator that comprises a first input/output (I/O) port, a second I/O port complementary to the first I/O port, and a second walk-off crystal located between the first I/O port and the second I/O port. The first I/O port includes a light coupling assembly, a first walk-off crystal and a split polarization rotator arranged in order along the optical axis. The light coupling assembly comprises a capillary and two optical fibers. The optical fibers are secured side-by-side in the bore of the capillary. The optical fibers each have a diameter of one half of the diameter of the bore. The cores of the optical fibers are separated from one another in a separation direction by a separation distance. The first walk-off crystal is located to receive the light beams and has a first walk-off direction perpendicular to the separation direction. The split polarization rotator is mounted adjacent the first walk-off crystal and has a positive half and a negative half.

Abstract: An optical subassembly and a method for mixing polarization components of light signals utilize an arrangement of walk-off crystals and half-wave plates. The optical subassembly can serve as a building block for fabricating a variety of optical devices, such as optical circulators, switches and filters. Preferably, the optical subassembly is utilized in conjunction with optical fibers having thermally expanded cores. The optical elements of the subassembly are arranged such that the optical subassembly is able to separate polarization components of two light beams and recombine them to form two new light beams. Each new light beam is formed by combining one polarization component of the first original light beam with a polarization component of the other original light beam. Various arrangements of walk-off crystals and half-wave plates can be utilized to construct the optical subassembly in accordance with the invention.

Abstract: A nonreciprocal optical device, preferably an optical circulator, and a method of transferring optical signals utilize a compensating lens coupled optically to a focusing lens. The compensating lens operates to correct misalignments caused by the focusing lens. The focusing lens and the compensating lens provide efficient coupling of optical fibers. Preferably, the compensating lens has a forward face with a number of flat surfaces that can refract light in a desired manner. In a first embodiment, two compensating lenses in optical series between two focusing lenses are utilized. In a second embodiment, only one compensating lens is utilized, but a mirror assembly is introduced so that polarization components of a light beam propagate through the compensating lens twice. In the first embodiment, the circulatory functions are accomplished by two optical assemblies and a shift plate.

Abstract: An optical assembly, such as a circulator, for selectively coupling first and third input/output windows at a forward end with a second input/output window at a rearward end includes a first group of optical elements that establish a desired orientation of polarization components for first and third beams that are respectively introduced via the first and third windows. In the preferred embodiment, the desired orientation is one in which the orthogonal polarization components of the third beam are shifted to locations on opposite sides of aligned polarization components of the first beam. A second functionally related group of optical elements functions as a polarization-dependent isolator for coupling the first beam to the second window and coupling an input beam from the second window to the rearward face of the first group of optical elements such that a rearwardly propagating beam from the second window is coupled to the third window.

Abstract: A compact, 2.times.n(n=1 or 2), polarization-independent optical component that comprises a first I/O port, a second I/O port and a polarization-changing optical element located between the first I/O port and the second I/O port. The second I/O port is optically aligned with the first I/O port. The first I/O port includes a serial arrangement of a first opposed walk-off crystal pair and a second opposed walk-off crystal pair, each opposed walk-off crystal pair comprising two walk-off crystals having opposite walk-off directions, the walk-off directions of the walk-off crystals of the first opposed walk-off crystal pair defining a first direction of rotation, the walk-off directions of the walk-off crystals of the second opposed walk-off crystal pair defining a second rotational direction, opposite to the first rotational direction.

Abstract: A switching element that selectively couples a first optical path to a second optical path through an index-matching fluid includes a tapering region along each of the optical paths to achieve high coupling efficiency at both ends of substrate waveguides that form portions of the two optical paths. The two substrate waveguides are separated by a gap that is filled with the index-matching fluid in order to optically couple the two waveguides. The ends of the waveguides located at the gap have relatively large cross sectional areas to promote high coupling efficiency across the gap. For example, the cross sectional dimensions may be approximately 16 .mu.m.times.8 .mu.m at the interior ends of the two substrate waveguides. On the other hand, the exterior ends have significantly smaller cross sectional areas in order to promote high coupling efficiency to optical fibers. For example, the cross sectional dimensions of an external end may be 8 .mu.m.times.8 .mu.m.

Abstract: An optical assembly, particularly for use as an optical circulator or optical isolator, includes utilizing an array of parallel thermally expanded core (TEC) fibers for transmitting light signals into and receiving light signals from an array of optical elements that is both polarization-dependent and non-reciprocal with respect to displacement of light propagating in opposite directions. In the preferred embodiment, the TEC fibers are precisely aligned using silicon V-groove techniques. Also in the preferred embodiment, focusing is used to improve the performance of the optical assembly. A microlens array reconverges the light energy of a polarization component that is propagating through the optical assembly separately from its associated polarization component. The array of microlenses may be formed into the glass substrate by diffusing ions through a photolithographic mask.