Silicon Dioxide Multi-Mode Interference Spectrometers

Area of Science:

• Photonics and Spectrometry
• Materials Science and Engineering

Background:

• Multi-mode interferometer (MMI) spectrometers reconstruct spectral information by analyzing light propagation patterns within waveguides.
• Previous MMI spectrometer designs utilized SU-8 core waveguides with etched nanograss scattering surfaces.

Purpose of the Study:

• To develop a fully silicon-based MMI spectrometer for enhanced performance and material compatibility.
• To investigate the fabrication of scattering features in silica core waveguides for improved light pattern imaging.

Main Methods:

• Fabrication of a silica core MMI waveguide with scattering features created using SU-8 nanograss as an etch mask.
• Utilized reactive ion etching (RIE) to transfer the SU-8 nanograss pattern into the silica core.
• Optimized RIE parameters for precise feature creation and waveguide performance.

Main Results:

• Successfully created a fully silicon-based MMI spectrometer.
• Achieved a signal-to-noise ratio (SNR) of three at an incident light power of -68 dBm.
• The silica core MMI spectrometer demonstrated a performance improvement of nearly 6 dB compared to SU-8 core designs.

Conclusions:

• The developed silica core MMI spectrometer represents a significant advancement in micro-spectrometer technology.
• The use of silicon-based materials and optimized RIE processes enables lower incident light power requirements.
• This technology holds promise for miniaturized and efficient spectral analysis applications.