In this paper we give an overview of the fabrication and assembly induced performance degradation of an intra-multi-chip-module free-space optical interconnect, integrating micro-lenses and a deflection prism above a dense opto-electronic chip.
The proposed component is used to demonstrate the capabilities of an accurate micro-optical rapid prototype technique, namely the Deep Proton Writing (DPW).
To evaluate the accuracy of DPW and to assess whether our assembly scheme will provide us with a reasonable process yield, we have built a simulation framework combining mechanical Monte Carlo analysis with optical simulations. Both the technological requirements to ensure a high process yield, and the specifications of our in-house DPW technology are discussed. Therefore, we first conduct a sensitivity analysis and we subsequently simulate the effect of combined errors using a Monte Carlo simulation. We are able to investigate the effect of a technology accuracy enhancement on the fabrication and assembly yield by scaling the standard deviation of the errors proportionally to each sensitivity interval.
We estimate that 40% of the systems fabricated with DPW will show an optical transmission efficiency above -4.32 dB, which is -3 dB below the theoretical obtainable value.
We also discuss our efforts to implement an opto-mechanical Monte Carlo simulator. It enables us to address specific issues not directly related with the micro-optical or DPW components, such as the influence of glueing layers and structures that allow for self-alignment, by combining mechanical tolerancing algorithms with optical simulation software. More in particular we determined that DPW provides ample accuracy to meet the requirements to obtain a high manufacturing yield.
Finally, we shortly highlight the basic layout of a completed demonstrator. The adhesive bonding of opto-electronic devices in their package is subject to further improvement to enhance the tilt accuracy of the devices with respect to the optical interconnect modules.