All-silicon interferometer with multimode waveguides for temperature-insensitive filters and compact biosensors

Area of Science:

• Photonics and optical engineering
• Integrated optics
• Silicon photonics

Background:

• Mach-Zehnder interferometers (MZIs) are widely used in optical systems but are sensitive to temperature fluctuations.
• Temperature-dependent shifts in the interference pattern can degrade device performance and limit applications.
• Developing temperature-independent optical devices is crucial for stable and reliable photonic systems.

Purpose of the Study:

• To design and demonstrate a novel all-silicon Mach-Zehnder interferometer (MZI) filter that exhibits temperature independence.
• To investigate the use of multimode waveguides within the MZI to achieve athermal operation.
• To explore the application of the proposed MZI structure in compact, high-sensitivity sensing devices.

Main Methods:

• Utilized a Mach-Zehnder interferometer (MZI) architecture with two arms of equal length and width.
• Employed multimode waveguides propagating different modes with distinct effective indices to create an optical path difference (OPD).
• Experimentally demonstrated a single-channel MZI filter and characterized its temperature sensitivity and sensing capabilities.

Main Results:

• Achieved a temperature-independent MZI filter with low temperature sensitivity ranging from -20 to 10 pm/°C in the C-band.
• Verified the operational principle through experimental measurements.
• Demonstrated a compact sensor based on the single-channel MZI structure with a high sensitivity of 826 nm/RIU.

Conclusions:

• The proposed all-silicon MZI design effectively mitigates temperature-induced shifts, enabling athermal operation.
• The athermal MZI filter is suitable for stable optical signal processing in the C-band.
• The MZI structure serves as a promising platform for developing highly sensitive compact optical sensors.