Rapid adiabatic couplers with arbitrary split ratios for broadband DWDM interleaver application

TL;DR

This paper presents a compact, broadband rapid adiabatic coupler with arbitrary split ratios, enabling scalable DWDM interleavers with low crosstalk over a wide wavelength range, suitable for integrated photonics.

Contribution

The authors demonstrate a novel design of rapid adiabatic couplers with arbitrary split ratios, achieving broadband operation and high scalability for DWDM applications.

Findings

Power split ratios within ±3% over 160 nm bandwidth.

Achieved < -20 dB crosstalk for 8-channel DWDM interleaver.

Maintains crosstalk below -10 dB across 40 channels with 100 GHz spacing.

Abstract

We experimentally demonstrate a compact and broadband rapid adiabatic couplers (RACs) with arbitrary power split ratios, achieved through the combination of translational offset and waveguide width control. Fabricated RACs of four different target split ratios show power splitting within $\pm$3% of the design target over a 160 nm wavelength range. Using these RACs, we implement an 8-channel dense wavelength division multiplexing (DWDM) interleaver exhibiting < -20 dB crosstalk for the center 8 channels with flat-top passbands. Over a broader wavelength range, the design maintains crosstalk below -10 dB across more than 40 channels with 100 GHz spacing, demonstrating the broadband capability and scalability of RAC-based photonic integrated circuits.