Design and Analysis of Free-Space Optical Interconnects

Student: Eng Swee Goh

Supervisor: Aleksandar Rakic

Category: Engineering Thesis Project - Communications

The continual development of more complex and efficient communication and computing systems has increased the demand of faster routing of information between elements such as chips and boards. With electronic interconnects fast approaching their limits, optical techniques seemed to be the best viable alternative. Free-Space Optical interconnects (FSOIs) seemed to be able solve the present data transfer bottleneck in high-speed computers and provide a key to the creation of a new architecture for the next generation of information processing systems.

All FSOI designs consist of two essential components they are the source and the detector. This thesis explores the integration of these devices with free-space optics into a system environment. One of the proposed interconnect solutions incorporate the use of macroscopic optics and micro optics. This combination is known as “Hybrid system”. Aberrations could be reduced or eliminated by improving the system geometry and steering the beams across the optical axis at the centre of the optical system. The introduction of prism optical elements can also be used to redirect the beams for board to board interconnections within a bay in hybrid systems.

Diffraction effects, which limits the performance of FSOI in the most significant way, was investigated and the received encircled energy was analysed at the detector of different channels in a hybrid system. Crosstalk an issue that affects channel optical signal-to-noise ratio (OSNR) and channel density was found to be higher in the centre channel than the corner channels in a three by three array VCSEL. It was also found that by designing a symmetric FSOI model with the location of the effective system aperture at the centre of the optical system, distortion could be eliminated.

Thesis Document (PDF)

Poster Presentation (PDF)