High-Efficiency Cladding-Free Thermo-Optic Modulators via 1T'-MoTe₂/Silicon Waveguides

Area of Science:

• Photonics and Optoelectronics
• Materials Science
• Integrated Optics

Background:

• Silicon photonics relies on efficient optical modulators for communication and sensing.
• Conventional thermo-optic modulators face trade-offs between thermal efficiency and optical loss.
• Existing designs using metallic or graphene heaters have limitations in scalability and performance.

Purpose of the Study:

• To develop a high-efficiency thermo-optic Mach-Zehnder modulator (TO-MZM) using 1T -MoTe₂/silicon hybrid waveguides.
• To overcome the limitations of conventional TO modulators, particularly in thermal efficiency and optical loss.
• To demonstrate a scalable and CMOS-compatible solution for next-generation optical modulators.

Main Methods:

• Fabrication of 1T -MoTe₂/silicon hybrid waveguides on silicon-on-insulator (SOI) substrates.
• In situ integration of 1T -MoTe₂ films for improved thermal transfer.
• Characterization of modulator performance at a 1550 nm telecommunication wavelength.

Main Results:

• Achieved a heating efficiency of 82.73 K·μm³/mW.
• Demonstrated an optimized phase-tuning efficiency of 0.396 π·mW^-1 with low optical loss.
• Successfully implemented the modulator in a 16-channel optical phased array for 30° beam steering.

Conclusions:

• The 1T -MoTe₂/silicon hybrid waveguide TO-MZM offers superior performance compared to existing electrically controlled TO-MZMs.
• The design provides a scalable, energy-efficient solution for advanced optoelectronic systems, including LiDAR.
• This work paves the way for next-generation silicon photonic devices with enhanced functionality and efficiency.