Compact CWDM interleaver based on an interfering loop containing a one-dimensional Fabry-Perot cavity.

We propose and experimentally demonstrate a compact silicon photonic interleaver based on an interfering loop containing a 1D Fabry-Perot (FP) cavity for coarse wavelength division multiplexing (CWDM) applications. The interleaver consists of a directional coupler and a FP cavity designed to minimize the channel crosstalk. Instead of using an off-chip optical circulator, the reflection light of the interleaver can be separated from the input by placing two identical interleavers in a Mach-Zehnder interferometer (MZI) structure for practical applications. We also study the impacts of fabrication errors of the MZI structure. The fabricated device has a footprint of 64  μm×70  μm and a channel spacing of ∼19  nm. The maximum crosstalk is -16  dB in a wavelength range from 1508 nm to 1590 nm.