Active alignment for a free-space optical backplane

uture high-performance digital computing systems will demand extremely high throughput backplanes to meet massive connectivity requirements between computing subsystems. This thesis begins by analyzing the characteristics of high-performance electronic backplanes and argues that electronic backplanes face fundamental cost/performance limitations which free-space optical backplanes can overcome provided key problems such as maintaining mechanical alignment in an industrial setting are resolved. An analysis of misalignment mechanisms indicates that active alignment is a powerful solution to the problem of optical alignment. A review of active alignment in other optical systems such as compact disk players and telescopes is then conducted.;The central part of this thesis presents the theoretical design, simulation, fabrication and testing of a novel active alignment demonstrator system based on Risley Beam Steerers. The demonstrator features a quadrant detector which detects the misalignment error between the centre of a spot of light and the centre of the quadrant detector. This misalignment error is then used by a new algorithm to calculate the rotational displacement required for the two Risley Beam Steerers to steer the spot of light to the centre of the quadrant detector. This experimental system contains all the necessary optics, optomechanics, electronics, and computer hardware and software required to demonstrate the task of centering the spot. The experimental results indicate that any spot misaligned by up to 160...