Tunable reflection/transmission switching using multimode interference with phase-change material.

Area of Science:

• Photonics and Materials Science
• Integrated Optics
• Non-volatile Optical Switching

Background:

• Non-volatile optical switches are crucial for developing programmable photonic integrated circuits.
• Efficient light routing and signal processing are essential for advanced optical communication systems.

Purpose of the Study:

• To propose and demonstrate a novel 2x2 photonic switch utilizing Sb$_{2}$S$_{3}$ phase transitions.
• To investigate the performance of the switch in terms of insertion loss, crosstalk, and bandwidth.
• To explore the potential for multi-level tuning and applications in reconfigurable photonic signal processing.

Main Methods:

• Fabrication of a photonic switch based on an Sb$_{2}$S$_{3}$-embedded multimode interference waveguide crossing.
• Utilizing Sb$_{2}$S$_{3}$ phase transitions triggered by total internal reflection for light path switching.
• Incorporating subwavelength tooth structures on reflecting facets to engineer optical field distribution via gradient-index effect.

Main Results:

• Achieved low insertion loss of 0.61 dB.
• Demonstrated low crosstalk below -21 dB over a 300 nm bandwidth.
• Confirmed stable device operation through fabrication tolerance analysis.
• Successfully achieved multi-level tuning of the power splitting ratio.

Conclusions:

• The proposed Sb$_{2}$S$_{3}$-embedded photonic switch is a promising component for non-volatile operation in programmable photonic integrated circuits.
• The device exhibits excellent optical performance, including low loss and crosstalk.
• Potential applications in reconfigurable photonic signal processing are highlighted due to its tunable power splitting capabilities.