Ultra-Broadband Interleaver for Extreme Wavelength Scaling in Silicon Photonic Links

We demonstrate an ultra-broadband silicon photonic interleaver capable of interleaving and de-interleaving frequency comb lines over a 125 nm bandwidth in the extended C- and L-bands. We use a ring-assisted asymmetric Mach Zehnder interferometer to achieve a flat-top passband response while maintaining a compact device footprint. The device has a 400 GHz free spectral range to divide an optical frequency comb with 200 GHz channel spacing into two output groups, each with a channel spacing of 400 GHz, yielding a potential capacity of 78 total wavelength-division multiplexed channels between 1525 nm and 1650 nm. This device represents an important step towards realizing highly parallel integrated optical links with broadband frequency comb sources within the silicon photonics platform.