Abstract: An optical device is provided which includes a slab waveguide and at least one input waveguide coupled to a first side of the slab waveguide. The device also includes a plurality of output waveguides coupled to a second side of the slab waveguide. The slab waveguide has a segmented transition region that includes a plurality of waveguiding regions spaced apart from one other by at least one discrete sector.

Abstract: A method and apparatus is provided for reformatting or interleaving a WDM signal that includes a plurality of optical channels having a first bandwidth and a first channel spacing. The method begins by receiving the WDM signal and dividing it into first and second subsets of optical channels each having a second channel spacing. Next, the first subset of optical channels are divided into third and fourth subsets of optical channels each having a third channel spacing. In addition, the second subset of optical channels is divided into fifth and sixth subsets of optical channels each having a fourth channel spacing. The third and fifth subsets of optical channels are combined to generate a first output WDM signal, while the fourth and sixth subsets of optical channels are combined to generate a second output WDM signal.

Abstract: A method and apparatus provides a WDM optical signal having a plurality of channels with a pair-wise orthogonal polarization state. The method begins by receiving a plurality of unpolarized optical wavelengths defining a plurality of optical channels separated by a prescribed channel spacing. A polarization wavelength dependent shift is imparted to the optical wavelengths, which is substantially equal to a particular fraction of the prescribed channel spacing.

Abstract: A method and apparatus provides a WDM optical signal having a plurality of channels with a pair-wise orthogonal polarization state. The method begins by receiving a plurality of unpolarized optical wavelengths defining a plurality of optical channels separated by a prescribed channel spacing. A polarization wavelength dependent shift is imparted to the optical wavelengths, which is substantially equal to a particular fraction of the prescribed channel spacing.

Abstract: An optical device is provided which includes a slab waveguide and at least one input waveguide coupled to a first side of the slab waveguide. The device also includes a plurality of output waveguides coupled to a second side of the slab waveguide. The slab waveguide has a segmented transition region that includes a plurality of waveguiding regions spaced apart from one other by at least one discrete sector.

Abstract: A method and apparatus is provided for reformatting or interleaving a WDM signal that includes a plurality of optical channels having a first bandwidth and a first channel spacing. The method begins by receiving the WDM signal and dividing it into first and second subsets of optical channels each having a second channel spacing. Next, the first subset of optical channels are divided into third and fourth subsets of optical channels each having a third channel spacing. In addition, the second subset of optical channels is divided into fifth and sixth subsets of optical channels each having a fourth channel spacing. The third and fifth subsets of optical channels are combined to generate a first output WDM signal, while the fourth and sixth subsets of optical channels are combined to generate a second output WDM signal.

Abstract: In accordance with the invention, an optical router for an optical communications system comprises a pair of transmissive Echelle gratings having their grating surfaces coupled by a waveguide grating. The arrangement provides for substantial design freedom in that the dispersive parameters include the shapes of the first and second Echelle gratings as well as the path length difference among the waveguides. Moreover the device eliminates any need for reflective surfaces in the Echelle gratings.

Abstract: An optical add-drop multiplexer (ADM) 60 avoids waveguide crossings by being constructed in the form of a Mach-Zehnder interferometer having a demultiplexer/multiplexer (demux/mux) pair 300, 400 in each of its arms. Each demux/mux pair is interconnected by coherent connecting paths 70, 80 having heating elements 65, 66 for increasing the path length of selected connecting paths. Waveguide optical couplers 61, 62 having asymmetric transfer functions are used at the input and output of the ADM. These couplers cooperate with the activated heating elements to add and/or delete a selected optical channel to/from an optical transmission path. Each coherent connecting path includes a number of waveguides. The end-to-end transmission characteristic of the ADM through each individual waveguide has a Gaussian shape. These Gaussian shapes are designed intersect at their −3 dB wavelengths so that the end-to-end transmission characteristic of the ADM is flat.

Abstract: The present invention teaches a novel technique for properly aligning the various channel positions of an optical signal splitter/combiner device, such as a DWDM, and associated optical transmitter(s), often a laser. In particular, the described technique establishes and utilizes feedback links between the operating temperature of the splitter/combiner and the operating temperature or operating current of the transmitter(s) to accurately manipulate the wavelengths of these devices in a manner that results in accurate alignment of the device wavelengths to the desired grid of channel positions, &lgr;0, &lgr;1, &lgr;2, &lgr;3, . . . , &lgr;n. Furthermore, by providing this active alignment or tracking scheme, the techniques of the present invention allows optical systems to more effectively operate at smaller channel spacings, i.e. ≦ about 50 GHz between adjacent channel positions, and with larger number of channels per device, i.e. ≧ about 32 channels.

Abstract: The present invention teaches a novel technique for properly aligning the various channel positions of an optical signal splitter/combiner device, such as a DWDM, and associated optical transmitter(s), often a laser. In particular, the described technique establishes and utilizes feedback links between the operating temperature of the splitter/combiner and the operating temperature or operating current of the transmitter(s) to accurately manipulate the wavelengths of these devices in a manner that results in accurate alignment of the device wavelengths to the desired grid of channel positions, &lgr;0, &lgr;1, &lgr;2, &lgr;3, . . . , &lgr;n. Furthermore, by providing this active alignment or tracking scheme, the techniques of the present invention allows optical systems to more effectively operate at smaller channel spacings, i.e. ≦about 50 GHz between adjacent channel positions, and with larger number of channels per device, i.e. ≧about 32 channels.

Abstract: The present invention teaches a novel technique for reducing the temperature-related spectrum shifts in optical devices, particularly waveguide grating routers (WGR). In general, the present invention modifies a portion of the length of at least one waveguide within an optical device in a manner that stabilizes the wavelength spectrum passing therethough even when exposed to temperature variations. More specifically, by knowing how the refractive index of a certain material changes with temperature variations as compared to that of common waveguide materials, such a silica, one may employ the teachings of the present invention to precisely modify the nature of the optical path through which a signal travels to fully compensate for any temperature-related wavelength spectrum shift. In other words, be able to produce an optical device with a plurality of waveguides each of which is appropriately modified so that any optical signal passing therethrough has the same wavelength at any two given temperatures.

Abstract: Optical devices, such as wavelength routers, having a plurality of waveguides of differing lengths, with improved independence to temperature fluctuations. Improved temperature independence is achieved by varying the cross-section of the device waveguides. Cross-section variation can be implemented in one or more of the following ways: selectively applying a temperature-compensating material (e.g., a polymer) over portions of the waveguides, and/or varying the dimensions and/or compositions of the materials used in the waveguides, either along each waveguide or between waveguides or both. By carefully designing the devices, the temperature effects resulting from the different lengths of the different waveguides can be compensated to produce a relatively temperature-independent device.

Abstract: In accordance with the invention, an optical multiplexer includes at least one reconfigurable add-drop unit that can add-drop one channel out of a large set by switching the light path through one of a set of fixed add-drop filters. Reconfiguration is done by switching from the add-drop filter path to a bypass path, changing to a different add-drop filter and then switching back. The phase delay of the bypass path is adjusted to maintain nearly maximum transmission during switching. The selection among add-drop filters is done by sliding an integrated optic chip with the set of add-drop filters between input and output waveguides. The reconfigurable add-drop multiplexer unit is latchable, passive between reconfigurations, and has low intrinsic insertion loss. Plural units in series can add/drop plural channels.

Abstract: An add/drop multiplexer (ADM) 100 includes an optical demultiplexer 200 and an optical multiplexer 300 that are connected in series. The optical multiplexer and the optical demultiplexer each include a number of corresponding passbands, which means that the central wavelengths of the multiplexer's passbands are approximately equal to the central wavelengths of the demultiplexer's passbands. The performance of the ADM is improved by making the edges of corresponding passbands complementary to each other. In one illustrative design, the transmission of the demultiplexer decreases at its passband edges as the wavelength moves away from its central wavelength, whereas the transmission of the multiplexer increases as the wavelength moves away from its central wavelength. The resultant cascaded passband of the pair is wider than the passband of the demultiplexer alone, thereby increasing the number of ADMs in a chain for the same performance.

Abstract: An optical interconnection device has a passive control mechanism for substantially eliminating thermal effects on optical properties of the apparatus Specifically, the interconnection apparatus includes a control material coupled to an optical circuit substrate, wherein the control material has a thermal expansion coefficient that is different than a substrate thermal expansion coefficient. In response to an increase or decrease an ambient temperature, the control material thermally expands or contracts at a different rate than the substrate to create a non-planar substrate distortion transmitted to the core portion, thereby creating a temperature independent optical path length within the optical core portion.

Abstract: An optical multiplexer/demultiplexer 500 comprises first and second star couplers 41, 42 that are interconnected by a number of optical waveguides 430 of unequal length (i.e., a grating). The multiplexer/demultiplexer functions to distribute optical signals in a first-wavelength region .lambda..sub.A (around 1550 nm) from one input port 401 of the first star coupler 41 to individual output ports 426 of the second star coupler 42 according to wavelength. The first star coupler includes at least one other input port 402 for receiving optical signals in a second wavelength region .lambda..sub.B (around 1310 nm) to be broadcast to all output ports of the second star coupler. In order to properly broadcast the optical signals in the second wavelength region, a power splitter 50 is connected in series with the other input port(s) of the first star coupler. The combined width w.sub.1 of the output port(s) of the power splitter is greater than the width w.sub.

Abstract: A computer system and method provide a CAD tool by which a mask for an application specific optical integrated circuit, chip, or wafer may be generated both easily and quickly. The method involves the step of receiving the design for an optical circuit with the circuit design including at least one optical component. Each optical component in the optical circuit is defined by one or more geometric shapes, such as a trapezoid, rectangle, or an arcuate polygon. The method further includes the step of retrieving parameters which define the manufacturing standard by which the optical circuit will be fabricated as well as parameters which define the optical components in the optical circuit. Based on the parameters and the geometric shapes, a plot is generated which forms a mask layout for the optical circuit. The mask layout can then be viewed by a graphical editor whereby a designer can receive visual confirmation that the mask layout accurately portrays the desired optical circuit, chip, or wafer.

Abstract: A dense waveguide division multiplexer (DWDM) is integrated on a single chip with a plurality of tunable attenuators that are connected in series to the output waveguides of the DWDM in order to equalize the power level on the output waveguides. In the preferred embodiment, the attenuators are thermo-optic Mach-Zehnder interferometer (TMZs) with a tunable range of 0 to 6 dB and a response time of approximately 1-10 milliseconds (ms). A heat sink is attached to the back of the chip to dissipate the heat from the TMZs and to reduce thermal crosstalk. In order to achieve a 3 dB loss on one of the output waveguides via the corresponding TMZ attenuator, approximately 0.25 W is required. In an alternative embodiment, the attenuators are variable stress Mach-Zehnder interferometers (VSMZs).

Abstract: A comb splitting system demultiplexes and/or multiplexes a plurality of optical signal channels at various wavelengths. The comb splitting system has at least two interconnected successive stages of wavelength division multiplexers (WDMs). The first stage comprises a Fourier filter that communicates bands of channels to respective WDMs of the second stage via suitable optical paths. Each of the bands has a plurality of the individual channels that are separated by at least one other of the channels. Each second stage WDM, which is allocated to a particular band, is interconnected to respective optical paths for carrying one or more individual channels. Furthermore, in accordance with a significant feature of the present invention, the passband width and periodicity (i.e., free spectral range) associated with the first stage Fourier filter are smaller than the passband width and periodicity associated with the second stage WDMs.

Abstract: This invention relates to a novel design for a low-loss optical power splitter, in particular Y-branch types resulting from chemical vapor deposition (CVD) fabricated silica waveguides. More specifically, the present invention utilizes mode matching of the fundamental modes between the input and the output waveguides of a splitter to optimize the splitters operational performance. The optical power splitter of the present invention comprising an input waveguide region having a predetermined width (W) and capable of transmitting optical energy having a fundamental mode E.sub.1.sup.0. Additionally, the splitter includes at least two output waveguide regions positioned to receive at least a portion the optical energy from the input waveguide region wherein the output waveguide regions each have predetermined widths (w) and are capable of transmitting optical energy having a fundamental mode E.sub.2.sup.