Patent Application
20100054655
This disclosure relates in general to optics and more particularly to a dynamic reconfigurable optical interconnect system.
Optical interconnects are likely replacements for traditional electrical interconnects between components on circuit boards. Unlike electrical interconnects, optical interconnects provide little or no signal propagation delay. In addition, optical interconnects provide for a significant increase to the available bandwidth of board-level interconnects.
Traditional optical interconnects employ predefined optical paths between data ports on various components. These paths typically consist of fixed optical channel waveguides that are formed on a substrate. These paths are dedicated paths that may only be utilized by the two data ports to which they connect. This results in an inflexible architecture for optical routing and chip-to-chip communication.
The present disclosure provides a dynamic reconfigurable optical interconnect system that substantially eliminates or reduces at least some of the disadvantages and problems associated with previous methods and systems.
According to one embodiment, an optical interconnect system includes an integrated circuit, at least one optical modulator, and a slab waveguide. The optical modulator is coupled to the integrated circuit and receives an input light beam from a light source and data from a source device and generates a modulated output light beam. The slab waveguide is coupled to the optical modulator and includes at least one input waveguide microlens, a plurality of output waveguide microlenses, and at least one deflector prism. The input waveguide microlens focuses the modulated output light beam from the modulator into a collimated light beam. The deflector prism is coupled to the integrated circuit, receives the collimated light beam from the input waveguide microlens, and deflects the collimated light beam toward one of the output waveguide microlenses according to an input voltage.
Technical advantages of certain embodiments may include a reduction in wiring density requirements for a circuit board, a decrease in the number of active elements required to interconnect optical ports on a circuit board, a reduction in the cost of the overall system, and/or an increase in overall system performance. Other advantages may include higher flexibility for optical signal routing, a reduction in the crosstalk between optical channels, and an increase in system bandwidth. Embodiments may eliminate certain inefficiencies such as requiring a dedicated optical channel waveguide between every optical data port on a circuit board. Some embodiments may also eliminate the need for additional multiplexing devices in order to provide wavelength multiplexing capabilities.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions, and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages.
For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
In operation, data source 110 outputs data to optical interconnect 120 via electrical data link 150. Optical interconnect 120 receives this data, along with a CW light beam from CW light source 140. Optical interconnect 120 generates a modulated light beam from the input CW light beam that corresponds to the data received from source device 110. This modulated light beam is then transmitted to one or more receiving devices 130 via optical links 160.
Optical interconnect 205 includes a main IC 210, a modulator 230, an input waveguide microlens 250, a deflector prism 240, a slab waveguide 220, and one or more output waveguide microlenses 290. Optical interconnect 205 could be utilized as optical interconnect 120, discussed above in connection with
Main IC 210 is coupled to modulator 230 and deflector prism 240. Main IC 210 is an example of source device 110 discussed above in connection with
In operation, CW light source 140 produces a CW light beam 260 and transmits it to modulator 230 in optical interconnect 205. CW light source 140 may be a laser, or any other device that produces a CW light beam. Modulator 230 receives CW light beam 260 and produces a modulated output light beam 270 corresponding to a data input. The data input may be from Main IC 210 or a modulator driver IC as described above. Modulator 230 transmits modulated output light beam 270 to input waveguide microlens 250 in slab waveguide 220. Input waveguide microlens 250 receives modulated output light beam 270 and generates a collimated light beam 280. Input waveguide microlens 250 transmits collimated light beam 280 to deflector prism 240. Deflector prism 240 receives collimated light beam 280 and directs it to an output waveguide microlenses 290 via slab waveguide 220. Each output waveguide microlens 290 is optically coupled to, and transmits the received collimated light beam 280 to, a receiving device 130.
Receiving devices 130 include optical detectors (not shown) which receive optical signals and convert them into electrical signals. In some embodiments, receiving devices 130 may additionally include filters (not shown) for filtering desirable wavelengths of light out of collimated light beam 280. Receiving device 130 may be, for example, an IC that is surface-mounted on a circuit board including the same circuit board as optical interconnect 205. If receiving device 130 is surface-mounted on a circuit board, 45 degree reflection mirrors (not shown) may be used to vertically redirect collimated light beam 280 to the optical detectors in receiving devices 130. Once collimated light beam 280 is converted into electrical signals by an optical detector, receiving device 130 then may process the data that was modulated onto collimated light beam 280.
Modulator 230 may be any optical modulator including, but not limited to, a typical electro-optic modulator. In one embodiment, for example, modulator 230 may be constructed of channel waveguides that are formed with three polymer layers: a lower cladding, an upper cladding, and a core layer in between the upper and lower cladding layer. The core layer may consist of an electro-optic material whose refractive index may be adjusted according to a voltage bias. Such modulators have been previously disclosed and are well known in the art. Modulator 230 may be optically coupled to input waveguide microlens 250 inside slab waveguide 220 in a variety of ways including, but not limited to, optical fibers and waveguides. In some embodiments, modulator 230 may simply be located adjacent to slab waveguide 220 and transmit output light beam 270 to input waveguide microlens 250 through air.
As noted above, modulated output light beam 270 travels from modulator 230, through input waveguide microlens 250 and deflector prism 240, and ultimately to an output waveguide microlens 290 via slab waveguide 220. Slab waveguide 220 may consist of three layers: a lower cladding layer, a core layer, and an upper cladding layer. Light travels through the core layer of slab waveguide 220 which may be constructed of a polymer or any material that allows light to propagate. The core layer and the cladding layers may be formed by various processes including, but not limited to, spin coating and thermal curing. The material of the core layer of slab waveguide 220 also has electro-optic properties that allow its refractive index to change when an electric field is applied. This change in refractive index almost instantaneously affects the light traveling through the core layer and enables deflector prism 240 to deflect collimated light beam 280 in a lateral direction in order to direct it to an output waveguide microlenses 290.
Input waveguide microlens 250 and one or more output waveguide microlenses 290 may be formed inside the core layer of slab waveguide 220 by various techniques. In one embodiment, plasma etching may be used to remove portions of the core layer of slab waveguide 220 in order to form lens-shaped cavities. A dispensing process may then be used to fill in the cavities with lens material fill-in in order to form input waveguide microlens 250 and one or more output waveguide microlenses 290.
To form the deflector prism 240 portion inside slab waveguide 220, two metal electrodes may be placed between the core and cladding layers of slab waveguide 220: one between the lower cladding layer and the core layer, and the other between the core layer and upper cladding layer. One of the electrodes may be in the shape of a prism and/or a triangle and both electrodes may be formed by processes including, but not limited to, sputtering and wet etching through patterned photoresist. Alternatively, the electrodes may be placed on the outside of the cladding layers so the cladding layers rather than the electrodes are adjacent to the core layer. In such an embodiment, the light passing through the core layer has less interaction with the metal electrodes and therefore less optical loss due to metal absorption will occur. Applying a voltage to the electrodes will change the refractive index of the core layer inside deflector prism 240 (the core material between the two electrodes that is made of electro-optic material) and thus cause the deflection of collimated light beam 280 in a lateral direction. Applying different voltages to the electrodes will cause the light to deflect in different directions.
In this manner, different voltages may be applied to deflector prism 240 in order to dynamically redirect collimated light beam 280 to different output waveguide microlenses 290. This provides a substantial improvement over existing optical interconnects. Typically, light beams travel from devices such as modulator 230 to devices such as output waveguide microlens 290 via channel waveguides. Channel waveguides provide only static connections between two optical devices. This embodiment, however, provides a way to dynamically control the destination of collimated light beam 280 by adjusting the voltage input to deflector prism 240. This provides improved flexibility, a decrease in the number of active elements required to interconnect optical ports on a circuit board, and a reduction in the cost of the overall system.
While the embodiment in
Dynamic reconfigurable optical interconnect system 300 operates similarly to dynamic reconfigurable optical interconnect system 200, described above in reference to
Dynamic reconfigurable optical interconnect system 300 provides significant advantages over typical static optical interconnects. In typical static optical interconnects, each optical connection requires a dedicated optical path including a separate light source and detector. For example, in a system with three ICs on one side of the substrate and three ICs on the other side of the substrate, a total of eighteen dedicated optical paths would be required to connect an input and output port on each device to the other three devices on the other side of the substrate. Each one of these dedicated optical paths would require a separate light source and detector. By utilizing the embodiments in this disclosure, however, the required components to implement the system would be greatly reduced since only one dynamic reconfigurable optical interconnect system 300 would be required for each direction of communications across the substrate. As a result, there is a significant reduction in the cost of the system, a reduction in the complexity of the system, and an overall increase in the design flexibility.
Another advantage of dynamic reconfigurable optical interconnect system 300 is provided by slab waveguide 220. Unlike typical optical interconnect systems that employ waveguide crossings and bends in order to create optical paths between devices, dynamic reconfigurable optical interconnect system 300 employs slab waveguide 220 which provides for the non-blocking crossing of collimated light beams 280. This significantly reduces and limits the crosstalk between optical channels that is present in typical optical interconnect systems.
In another embodiment, multiple CW light sources 140 with different wavelengths λ may be utilized to create an optical interconnect with wavelength multiplexing capabilities. For example,
This embodiment provides many advantages over typical planar multiplexing devices. One advantage is that this embodiment may be fabricated using ordinary fabrication techniques. Typical planar multiplexing devices require very sophisticated fabrication techniques due the high requirements for dimensional accuracy. In addition, typical planar multiplexing devices are static and do not allow for reconfiguration. This embodiment, however, provides for a highly configurable and flexible switching system. In this embodiment, the multiplexing of signals can be turned on and off by adjusting the voltage to deflector prism 240. In addition, a different number of inputs may be multiplexed together depending on the required operation.
While particular embodiments have been described in detail, numerous changes, substitutions, variations, alterations and modifications may be ascertained by those skilled in the art, and it is intended that the present disclosure encompass all such changes, substitutions, variations, alterations and modifications as falling within the spirit and scope of the appended claims.
With reference now to
While a particular optical interconnect method 500 has been described, it should be noted that certain steps may be rearranged, modified, or eliminated where appropriate. Additionally, while certain embodiments have been described in detail, numerous changes, substitutions, variations, alterations and modifications may be ascertained by those skilled in the art, and it is intended that the present disclosure encompass all such changes, substitutions, variations, alterations and modifications as falling within the spirit and scope of the appended claims.
