Design and Tolerancing of Planar Optoelectronic Systems Utilizing Diffractive Optics.
The use of diffractive optics in free-space optical interconnect applications has been shown to provide superior performance for distances over 1 mm. However, problems due to packaging (alignment, heat dissipation, etc.) and optoelectronic/electronic integration issues has limited their use in commercial applications. This work studies some fundamental design and alignment issues related to both space variant and space invariant systems. The design of space variant systems is shown to be more complex requiring high level system placement algorithms and component-level design methods to minimize the diffraction losses. The design method depends greatly on the type of illumination in the system, either Gaussian or uniform. It is shown that Gaussian illumination better conserves the optical power at the expense of smaller distances. It is also shown that in most cases for uniform illumination, iterative techniques are required in order to optimize the optical throughput. The effects of misalignments on system performance is discussed and a method is developed to calculate the optical throughput of a space variant system with arbitrary misalignments. This method is then used to conduct studies into misalignment sensitivity and tolerance design given system level specifications. A tolerancing design of space variant systems with board-level interconnect distances (~15 cm) shows that using current technology that free-space optical interconnect systems can be commercially viable. However, special design techniques will likely be required in order to meet typical wavelength variations of laser diodes. A similar study for space invariant systems is undergone. Since space invariant systems do not have significant diffraction effects inside the system, standard optical design software are utilized to design and study the optical throughput losses due to misalignments. A method based on the point spread function is shown to be able to calculate the optical throughput for general misaligned space invariant systems. This is again used to study misalignment effects on the system with the result that most misalignments are less constrained when compared to the space variant case. However, three rotational misalignments are shown to have a greater impact on the optical throughput.
- Pub Date:
- January 1995
- Engineering: Electronics and Electrical; Physics: Optics