All-silicon monolithic Mach-Zehnder interferometer as a refractive index and bio-chemical sensor

Area of Science:

• Photonics
• Integrated Optics
• Biomedical Sensing

Background:

• Mach-Zehnder interferometers (MZIs) are crucial for sensing applications.
• Monolithic integration of complex photonic devices on silicon presents significant challenges.
• Broadband light sources typically require wavelength-specific detection in interferometry.

Purpose of the Study:

• To present a complete Mach-Zehnder interferometer monolithically integrated on silicon.
• To demonstrate its application as a refractive index and biochemical sensor.
• To establish the potential for real-time, in-situ monitoring.

Main Methods:

• Monolithic integration of broadband light sources, single-mode waveguides, and photodetectors on silicon.
• Photonics engineering of the MZI for wavelength-independent phase difference.
• Integration of fluidic and interconnect components for on-chip measurements.

Main Results:

• Demonstration of a complete, monolithically integrated silicon Mach-Zehnder interferometer.
• Achieved wavelength-independent phase difference enabling broadband operation.
• Successful refractive index and protein sensing with sinusoidal photocurrents.
• This is the first silicon device to achieve complete on-chip interferometry.

Conclusions:

• The developed silicon MZI sensor is suitable for real-time, in-situ refractive index and biochemical monitoring.
• The device's unique design overcomes limitations of broadband light sources in interferometry.
• This technology represents a significant advancement in integrated photonic sensing platforms.