Fabrication of 1 × N integrated power splitters with arbitrary power ratio for single and multimode photonics

Abstract

Compact power splitters are essential components in integrated optics. While 1 × 2 power splitters with uniform splitting are widely used, a 1 × N splitter with arbitrary number N of ports and arbitrary splitting ratio is yet to be demonstrated. In this work we address this problem. We fabricate and characterise 1 × N integrated power splitters that provide fully arbitrary splitting ratios. The core of our design is represented by an array of N non-equally spaced waveguides fabricated on a silicon nitride-on-insulator wafer. Any arbitrary 1 × N splitting ratio can be achieved by properly setting the array length and the dimension of the (N–1) nano-gaps between the adjacent waveguides. Most importantly, at variance with state-of-the-art solutions, our devices can be designed for arbitrary splitting of higher-order modes. In this manuscript we provide the first experimental demonstration of 1 × N arbitrary splitting ratio for both the fundamental modes (TE00 and TM00) and the TE01 mode, here up to N = 5 ports. With a footprint of 20 μm2/port, a bandwidth up to 70 nm and an excess losses <0.2 dB, our devices set a new benchmark for optical power splitters in both standard single-mode photonics as well as in the emerging integrated multimode photonics technology, and may therefore boost key photonic applications, from optimal power distribution and equalization up to signal processing operations.

Keywords

• integrated photonics
• power splitting
• multimode
• silicon nitride