Hybrid Graphene-Silicon Based Polarization-Insensitive Electro-Absorption Modulator with High-Modulation Efficiency...

Area of Science:

• Photonics and Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Conventional optical modulators are limited to single-polarization states, hindering high-capacity on-chip optical interconnects.
• Achieving polarization-insensitive modulation is crucial for next-generation optical communication systems.
• Graphene-silicon hybrid structures offer potential for advanced modulator designs due to tunable optical properties.

Purpose of the Study:

• To propose and demonstrate a hybrid graphene-silicon-based polarization-insensitive electro-absorption modulator (EAM).
• To enhance light-graphene interaction for improved modulation efficiency and bandwidth.
• To achieve high-performance modulation suitable for on-chip optical interconnects.

Main Methods:

• Fabrication of a hybrid graphene-silicon waveguide using multi-deposited and multi-transferred methods.
• Optimization of waveguide dimensions to maximize light interaction with graphene in the intense field region.
• Characterization of modulation efficiency, modulation depth, insertion loss, and bandwidth for both polarizations.

Main Results:

• Achieved polarization-insensitive modulation with a modulation efficiency (ME) of ~1.11 dB/µm and a discrepancy < 0.006 dB/µm.
• Demonstrated an EAM with a length of 20 µm exhibiting a modulation depth (MD) > 22 dB and insertion loss < 0.23 dB at 1.55 µm for both polarizations.
• Obtained an ultra-broad bandwidth exceeding 300 nm while maintaining MD > 20 dB and MD discrepancy < 2 dB.

Conclusions:

• The proposed hybrid graphene-silicon EAM overcomes the polarization limitation of conventional modulators.
• The device offers superior modulation efficiency, ultra-broad bandwidth, and low insertion loss, making it ideal for high-capacity on-chip optical interconnects.
• This work paves the way for advanced photonic integrated circuits and optical communication systems.