Polymer Spot Size Expanders for High Efficiency Optical Coupling in Optical Interconnection

Abstract

Improving the low coupling efficiency due to spot size differences remains a challenge for achieving high bit-rate optical interconnections. To solve this problem, the test spot size expander device is fabricated using UV-curable resin on the end face of a fiber with a high numerical aperture. The expanded spot size of 9.38 μm from the original 3.2 μm at a wavelength of 1.55 μm and the maximum coupling efficiency with a single mode fiber of –1.19 dB are achieved. In addition, the –3 dB tolerance of the coupling efficiency along the vertical optical axis was ±4.1 µm.