On-chip multi-dimensional multiplexing communication using tapered adiabatic micro-ring resonators

Abstract

Multi-dimensional multiplexing plays a vital role in on-chip optical communication for enhancing capacity density. However, the mode (de)multiplexer based on multimode interferometer is generally wavelength dependent, which brings a non-negligible conundrum to fabricate multi-dimensional (de)multiplexers. Herein, we propose an on-chip multi-dimensional (de)multiplexer by designing a tapered adiabatic micro-ring resonator (TAMR), and perform a 4-mode bending transmission via a pixelated meta-structure. The TAMR is designed with a negligible wavelength dependence because of non-coherent superposition (No-coherent superposition mechanism based on directional coupling avoids the coherent superposition of light-waves, which will not reduce the working bandwidth.of device.), but employs the periodic energy exchange of evanescent wave between two waveguides to achieve an equal phase velocity for the fundamental and higher-order modes (mode conversion), where a micro-ring resonator array is exploited for resonance frequency selection. A pixelated meta-structure implemented by writing nano airholes in the silicon slab is employed for addressing the mode distortion induced by the bending of transverse electric (TE) modes. Consequently, we construct a 12-channel multi-dimensional (de)multiplexer composed of 3 wavelengths and 4 TE modes. We show that all the channels are successfully (de)multiplexed with crosstalk less than − 19 dB, and bit error rates lower than 3.8 × 10−3 at the signal to noise ratio of 17 dB.