High-performance Ge/Si electro-absorption optical modulator up to 85°C and its highly efficient photodetector...

Area of Science:

• Photonics and Optoelectronics
• Materials Science
• Semiconductor Devices

Background:

• High-bandwidth optical interconnects are crucial for modern computing.
• Germanium/Silicon (Ge/Si) heterostructures offer potential for integrated optoelectronic devices.
• Temperature stability is a key challenge for high-speed optical modulators.

Purpose of the Study:

• To investigate the high-speed performance of a Ge/Si electro-absorption modulator (EAM) over a wide temperature range.
• To evaluate the Ge/Si device's capability as a photodetector.
• To assess the suitability of Ge/Si stacked structures for integrated silicon photonics.

Main Methods:

• Fabrication of a Ge/Si EAM evanescently coupled with a silicon waveguide.
• High-speed operation testing at temperatures from 25°C to 85°C.
• Photoluminescence spectroscopy to analyze temperature-dependent bandgap energy.

Main Results:

• Demonstrated 56 Gbps high-speed operation of the Ge/Si EAM up to 85°C.
• Observed minimal bandgap energy shift with temperature, consistent with wavelength shifts.
• Confirmed dual functionality as a high-speed, high-efficiency Ge photodetector utilizing Franz-Keldysh and avalanche effects.

Conclusions:

• The Ge/Si EAM exhibits robust high-speed performance across a broad temperature range.
• The Ge/Si stacked structure is a promising platform for integrated optical modulators and photodetectors.
• This technology advancement supports the development of high-performance silicon photonic integrated circuits.