Structure of 25-Gb/s Optical Engine for QSFP Enabling High-Precision Passive Alignment of Optical Assembly

Abstract

We propose a novel structure for optical assembly that enables high-precision passive alignment assembly process for our flexible printed circuit -- based optical engine. The optical engines are fabricated with less than 7 µm of misalignment between optical devices and polymer waveguides. This high-precision alignment suppresses the optical coupling losses to an average of 2.9 dB for the transmitter side and, 1.6 dB for the receiver side. The optical engines are installed to a high-volume product of 100 Gb/s quad small form-factor pluggable (QSFP) optical transceivers. The QSFP demonstrated clear eye opening and error-free operation at 100Gb/s with high yield rate thanks to the low-coupling loss resulting from the high-precision alignment of optical devices.