The invention relates generally to optical circuits and, more particularly, to a method and apparatus for conveying optical signals in a flexible package.
In recent years, processor speeds have increased while electronics packages have decreased in size. The increased processor speeds and decreased package size have enabled tremendous increases in digital data rate capabilities, thus enabling miniaturization of high-speed digital devices such as cell phones, camcorders, laptop and desktop computers, and digital televisions, as examples. In addition, because of the tighter space requirements and miniaturization, the processors and components are typically fabricated on small printed circuit boards or multi-layer flexible circuits. In a cell phone application, for instance, the components may be placed on a multiple layer flexible circuit so that a hinge may be formed between two halves of the circuit, thus enabling the cell phone to be opened and closed using the flexible nature of the circuit at the hinge, while enabling components to be placed on a single circuit.
In order to convey these tremendous rates of digital data in affordable and manufacturable devices, different solutions have been applied in the industry that include electronics-only and optical configurations that are typically mounted on a flex circuit or a board having a multi-layer flexible circuit therebetween. For instance, in an electronics-only solution, multiple parallel paths may be built into a multi-layer flexible circuit that enable high rates of digital data to be conveyed simultaneously and in parallel. As the number of parallel paths increases, so too does the capability for high-speed data transmission. However, such configurations also may increase the propensity for cross-talk and electromagnetic interference (EMI) in the parallel portions of the circuit. One option includes an electrical micro-coax, which becomes lossy, expensive and less flexible as frequency increases. Further, as the number of parallel paths increases, circuit cost and complexity increase as well. Thus, in such solutions, though circuits may meet the data rate needs, a trade off may be made in terms of manufacturing cost and yield, as well as performance and signal interference due to the parallel data transmissions.
Solutions using optical components may decrease the propensity for cross-talk, because optical signals typically do not emit EMI, nor are the optical components typically subject to EMI interference from other electrical components. The solutions that include optical devices typically include optical connectors with driving electronics on a main board or multiple separate optical transceiver modules. In such configurations, although the amount of cross-talk may be decreased when compared to an electronics-only solution, such configurations may find limited application because of the additional power requirements and space/packaging requirements for driving electronics or transceivers. In addition, such configurations typically may not be tested in the fabrication process until a final assembly is complete. For instance, in a cell phone application, when installing optical components, the optical links may not be tested or testable until the cell phone is at or near its final stage of manufacture. Thus, failure of a component may not be uncovered until late in the manufacturing process, resulting in costly trouble-shooting and re-work, or costly disposal of the entire device, including the transmitting and receiving components thereof.
Therefore, it would be desirable to design an apparatus and method providing increased data rate capabilities in digital electronics devices, while decreasing package size, power requirements, cross-talk, and overall manufacturing costs.