Packaging-enhanced optical fiber-chip interconnect with enlarged grating coupler and multimode fiber

TL;DR

This paper introduces a packaging-enhanced optical fiber-chip interconnect using enlarged grating couplers and multimode fibers, significantly improving alignment tolerance and reliability for lab-on-a-chip systems.

Contribution

It proposes a novel large-area grating coupler design combined with multimode fibers, achieving higher spatial tolerance and simplifying fiber-to-chip connections.

Findings

Achieved 10.2 μm and 17.3 μm in-plane spatial tolerance.

Tolerance is at least 2.49 and 3.33 times larger than small area couplers.

Experimental results align well with theoretical predictions.

Abstract

Optical I/O plays a crucial role in the lifespan of lab-on-a-chip systems, from preliminary testing to operation in the target environment. However, due to the precise alignments required, efficient and reliable fiber-to-chip connections remain challenging, yielding inconsistent test results and unstable packaged performance. To overcome this issue, for use in single mode on-chip systems, we propose the incorporation of area-enlarged grating couplers working in conjunction with multimode fibers. This combination enables simpler, faster, and more reliable connections than the traditional small area grating coupler with single-mode fiber. In this work, we experimentally demonstrate a 3dB in-plane (X, Y) spatial tolerance of (10.2 {\mu}m, 17.3 {\mu}m) for the large area configuration, being at least (2.49, 3.33) times that of the small area one, and agreeing well with theoretical calculations. The simple concept is readily applicable to a range of photonic systems where cheaper more robust optical I/O is desired.