A Digital Optical Switch Based on a Thermally Tuned Multimode Waveguide Grating Filter

TL;DR

This paper introduces a robust, low-power digital optical switch based on a thermally tuned multimode waveguide grating filter, capable of operating across wide voltage ranges with high performance and simplified digital control.

Contribution

The paper presents a novel thermally tuned MWG filter switch with wide voltage tolerance, reduced power consumption, and compatibility with digital signals, improving practicality and efficiency.

Findings

Operates across two voltage ranges with a 0.6 V margin

Reduces power consumption by two-thirds to 6 mW

Offers low insertion loss, high extinction ratio, and fast switching

Abstract

All-optical switching technology is a key solution to the future energy crisis in AI computing, where the performance of optical switches plays a critical role. Conventional integrated optical switches typically suffer from poor robustness to voltage fluctuations, fabrication variations, and temperature drifts. These limitations necessitate complex high-precision real-time calibration and control circuits, which greatly restrict their practical use. This paper presents a digital optical switch based on a thermally tuned multimode waveguide grating (MWG) filter. The switch maintains its on- and off-states across two voltage ranges: 0-0.7 V and 1.1-1.7 V, with a wide operating voltage margin of 0.6 V. It also exhibits excellent robustness to fabrication variations and temperature drifts. By introducing an innovative combination of positive dispersion and parabolic apodization design, the power consumption is reduced by two-thirds, reaching a maximum of only 6 mW. Owing to its low power consumption and wide voltage range, the device can be directly driven by digital signals, allowing for a simplified driver circuitry and a significant reduction in both energy use and overall cost. In addition, the switch offers low insertion loss (<0.5 dB), high extinction ratio (>20 dB), and fast switching (300 {\mu}s), demonstrating excellent overall performance and promising application prospects.