100 GHz micrometer-compact broadband monolithic ITO Mach-Zehnder interferometer modulator enabling 3500 times higher...

Area of Science:

• Photonics and Materials Science
• Integrated Optics
• Semiconductor Devices

Background:

• Electro-optic modulators are crucial for optical transceivers and photonic integrated circuits (PICs) in machine learning and signal processing.
• Existing silicon and lithium-niobate modulators face limitations in achieving both high chip density and fast switching speeds simultaneously.
• Current-driven indium tin oxide (ITO)-based modulators present a promising avenue due to efficient light-matter interactions.

Purpose of the Study:

• To introduce novel micrometer-compact Mach-Zehnder interferometer (MZI)-based electro-optic modulators.
• To demonstrate modulators capable of exceeding 100 GHz switching rates.
• To enable high-density integration for next-generation computing and communication applications.

Main Methods:

• Integration of ITO-thin films atop photonic waveguides to create compact MZI phase shifters.
• Holistic optimization of photonic, electronic, and radio-frequency (RF) aspects of the modulator design.
• Implementation of an asymmetric MZI tuning step and dielectric thickness sweep for optimizing performance trade-offs (extinction ratio, insertion loss, and speed).

Main Results:

• Achieved efficient MZI phase shifters with a figure of merit (VπL) of 0.1 V·mm, exhibiting broadband spectral characteristics.
• Demonstrated micrometer-compact MZI modulators with switching rates exceeding 100 GHz.
• Enabled integration of over 3500 modulators in the same chip area as a single silicon MZI modulator, driven by CMOS-compatible bias voltages.

Conclusions:

• The developed ITO-based MZI modulators offer a significant advancement in modulator technology, overcoming limitations of existing silicon and lithium-niobate devices.
• These modulators provide a pathway to meet the demands for high-density, high-speed optical components in machine intelligence, edge/cloud computing, and advanced optical transceivers.
• The device represents a critical step towards realizing the full potential of photonic integrated circuits for future high-performance electronic systems.