Abstract: The invention relates to waveguiding structures in planar lightwave circuit devices that include a transition region between a slab waveguide and channel waveguides to reduce optical coupling loss. In particular star couplers and arrayed waveguide gratings incorporating the transition region of the present invention demonstrate reduced insertion loss. By creating a transition region composed of transverse rows intersecting the output waveguide array, where the rows have equal dimensions and the effective refractive index is controlled by increasing the spacing width gradually from row to row, an adiabatic transition is created from slab waveguide to channel waveguide array. This structure provides low insertion loss within practical manufacturing tolerances. In addition, the present invention has found that by incorporating the transition region of the present invention into an AWG, the reduced insertion loss can be controlled as uniform insertion loss across the channels.

Abstract: The invention relates to optical communications using techniques for providing efficient high speed polarization bit interleaving. One common architecture for high-speed time-division-multiplexing employs two modulators having a same bit rate, wherein two separately modulated streams of data bits are combined into a high-speed single serial stream of data bits, instead of providing a single higher-cost higher-speed modulator. The present invention has found with the availability of fast data modulators, that polarization bit interleaving can be employed more efficiently for higher speed data transmission in optical network systems by providing an optical modulator including a single data modulator, rather than multiplexing different data streams from different modulators.

Abstract: The invention relates to optical communications using techniques for providing efficient high speed polarization bit interleaving. One common architecture for high-speed time-division-multiplexing employs two modulators having a same bit rate, wherein two separately modulated streams of data bits are combined into a high-speed single serial stream of data bits, instead of providing a single higher-cost higher-speed modulator. The present invention has found with the availability of fast data modulators, that polarization bit interleaving can be employed more efficiently for higher speed data transmission in optical network systems by providing an optical modulator including a single data modulator, rather than multiplexing different data streams from different modulators.

Abstract: An optical device having a first substrate having a fast optical axis and a slow optical axis and a first end and a second substrate having a fast optical axis and a slow optical axis and a second end, the second end is positioned adjacent to the first end such that the fast optical axis of the first substrate is coupled to the slow optical axis of the second substrate and the slow optical axis of the first substrate is coupled to the fast optical axis of the second substrate, thereby permitting an optical signal to pass between the first and second substrates. The first substrate and the second substrate have substantially equal length to thereby substantially eliminate polarization dispersion.

Abstract: A digital optical switch and a method for digital optical modulation are disclosed. The digital optical switch is comprised of an optical waveguide having an input control region, a connection region, and a separation region, and a generator which generates a smoothly varying electric field in an input control region of said optical waveguide and a substantially constant electric field in said separation region of said optical waveguide. The optical waveguide may be either an x-shaped optical waveguide or a y-shaped optical waveguide.

Abstract: A hybrid optical switching-fabric architecture, for implementation via Y-branch switching elements, comprises an 8.times.8 array (100) of eighty Y-branch switching elements (110) configured as a Benes outer layer (105) consisting of two columns (105a, 105b) of four 2.times.2 networks (103) and an active-splitter/active-combiner inner layer (106) consisting of one column of two 4.times.4 active-splitter/active-combiner networks (104).

Abstract: A three or more section reverse .DELTA..beta. directional coupler designed to operate at a number of coupling lengths (L/l) selected from a region of a corresponding switching diagram where the cross and bar state switching curves are approximately parallel to each other and to the vertical axis, the vertical axis defining numbers of coupling lengths, or from a region of corresponding process sensitivity plots for the cross and bar states where the cross and bar state voltage curves are both approximately of zero slope. A number of these directional couplers form an optical switching array and a number of arrays form a system or network for switching optical signals each of which are capable of operation with uniform cross and bar state voltages at low crosstalk levels.

Abstract: A leadframe-based optical assembly is disclosed which is suitable for use with either transmitter or receiver optical assemblies. The leadframe includes a number of separate sections, each leadframe section being associated with a separate optical assembly. A particular leadframe section includes a first contact lead with an aperture therethrough such that the active region of the optical may be aligned with the aperture. A first electrical connection is made between the first lead and the optical device surface containing the active region. The remaining electrical connection is provided by a second contact lead which is wire bonded to the opposing surface of the optical device. A fiber section (fiber-containing ferrule) is attached to the opposite side of the leadframe in the vicinity of the first contact aperture to provide coupling between the optical fiber and the active region. Lensed fibers and/or semiconductor optical devices may be used to increase coupling efficiency.

Abstract: A groove is disposed in a substrate longitudinally along the outside radius of a bent integrated optical waveguide to constrain the mode of optical energy propagating therein such that the optical energy that would normally be radiated is confined to the waveguide, thereby reducing transmission loss through the bend. Further, to reduce coupling loss between an integrated optical waveguide and an optical fiber, two grooves are disposed longitudinally along either side of the integrated optical waveguide to constrain the mode of optical energy propagating in the waveguide to approximate the mode of the optical energy propagating in the optical fiber. To further reduce both bend and coupling losses, the ends of the grooves bend away from the waveguide.

Abstract: An array connector for optical fibers is disclosed which utilizes a plurality of grooves formed in the array substrate to hold the fibers. The connector is to be used with fibers having at least one sectional view substantially flattened side, where polarization maintaining fibers may be formed to assume this shape. The grooves are formed to have a relatively flat bottom surface so that the flattened side of the fiber is positioned to coincide with this flat bottom surface. The grooves themselves may have any desired cross section. A coverplate with corresponding grooves may be utilized to form an interlocking structure to prevent any lateral movement by the fibers. When used in association with polarization maintaining fibers, the connector of the present invention will preserve the polarization through the connection by preventing any axial angular motion. The connector may be used to align a plurality of fibers with another plurality of fibers or, alternatively, with a plurality of optical waveguides.

Abstract: An arrangement for providing optical coupling between a pair of substrates is disclosed. The arrangement is capable of providing automatic alignment in the lateral direction, that is, the direction perpendicular to the direction of optical signal flow along the surface of the optical substrate. In accordance with the teachings of the present invention, an interlocking system of alignment grooves and alignment ridges are utilized to prevent this unwanted motion and aid in alignment between the two pieces. In particular, an alignment ridge, or ridges, are formed on the top surface of a first substrate and are disposed to be parallel with a plurality of optical waveguides formed in the first substrate. The corresponding alignment grooves are formed in the second substrate, where this substrate may contain a plurality of fibers held in associated v-grooves. Waveguide-to-waveguide communication is achieved by forming alignment ridges on a pair of waveguide containing substrates.

Abstract: An optical fiber-to-waveguide coupler is disclosed which automatically aligns five of the six possible degrees of freedom associated with the alignment process. Silicon v-grooves (22) are used to hold the fibers (24) in place in the silicon substrate (20), but in contrast to prior art arrangements, the silicon substrate overlaps the top surface (12) of the waveguide substrate (14). A cover plate (26) disposed over the silicon substrate is cut and polished so that the endface of the cover plate (28) lies in the same plane as the ends of the fibers (30). When the endface of the cover plate is butted against the endface (16) of the waveguide substrate, and the silicon v-grooves have been etched to the proper predetermined depth, five of the six degrees of freedom are automatically aligned.

Abstract: A laser or other source of radiant electromagnetic energy removes optically transparent material (e.g., LiNbO.sub.3) to form various structures. To enhance coupling the radiant energy to the optical material, a layer of an ablative absorber (e.g., a metal or organic material) can be used. Alternately, the radiant source can be initially operated above a threshold that causes removal of a surface layer of the optical material. After selectively thus removing a surface layer of the optical material, subsequent sub-threshold applications of radiant energy remove additional optical material due to a change in the underlying material, rendering it more absorptive at the wavelength of the electromagnetic energy. Optical devices, including waveguides, can be formed, as well as isolation grooves, alignment structures, etc.

Abstract: The specification describes a technique for etching titanium using EDTA compounds. It is especially useful for selective etch processes such as those used to form titanium diffused waveguides in lithium niobate crystals.