An On-Chip Triplexer Based on Silicon Bragg Grating-Assisted Multimode Interference Couplers

A silicon triplexer based on Bragg grating-assisted multimode interference (MMI) couplers is designed and experimentally demonstrated. Compared with the conventional MMI-based triplexers, the device length is not required to be the common multiple of beat length of different wavelengths. The simulated bandwidth is over 100 nm for 1310-nm band with the 3-D finite-different time-domain method. Experimental results of the fabricated on-chip triplexer show extinction ratios higher than 15 dB and insertion losses around 1 dB in all output ports. The total device size is only
$5.4 \times 453\,\,\mu \text{m}^{\mathrm {\mathbf {2}}}$
, which is the smallest size over the experimentally demonstrated triplexers ever reported.