Flexible pillars for displacement compensation in optical chip assembly

In chip-to-chip optical interconnect systems with surface mounted light-sources and detectors, thermal and mechanical effects can cause lateral displacements of the assembled devices. These displacements can result in optical signal losses that can critically deteriorate the bit-error-rate of the digital system. We demonstrate that, for a given loss budget of 1 dB, the use of flexible optical pillars with 150-μm height and 50-μm diameter can double the lateral displacement tolerance from about 15 to 30 μm. The pillars fabricated from Avatrel polymer form an air-free path between the light source and the substrate and cause maximum optical power losses less than 0.2 dB.