Highly Compact and Efficient Four-Mode Multiplexer Based on Pixelated Waveguides

Abstract

An ultra-compact mode multiplexer for TE0, TE1, TE2 and TE3 modes is proposed and demonstrated experimentally. The device is realized via pixelated waveguides with a footprint of only $5.4\times 6~\mu \,\,\text{m}^{2}$ . The measured insertion loss of the multiplexer is less than 1.5 dB. The inter-mode crosstalk is ~−20 dB at 1550 nm and below −14.6 dB from 1510 nm – 1570 nm. The fabrication and temperature tolerance of the device are investigated. The device can well tolerate the nanohole diameter variation of ±10 nm and the temperature variation of 100 K. The compactness of the proposed mode multiplexer enables potential applications in densely integrated multimode photonic circuits.