Wavelength-scale noise-resistant on-chip spectrometer

Area of Science:

• Photonics
• Nanotechnology
• Spectroscopy

Background:

• On-chip spectrometers are crucial for sensing technologies like environmental monitoring and biomedical diagnostics.
• Existing spectrometers face accuracy limitations due to small footprints and noise sensitivity.

Purpose of the Study:

• To demonstrate a wavelength-scale, CMOS-compatible on-chip spectrometer.
• To overcome accuracy constraints of previous designs using inverse-designed quasinormal modes.

Main Methods:

• Utilized inverse-designed quasinormal modes within a complex photonic resonator.
• Engineered modes to extend effective optical path length beyond physical device dimensions.
• Fabricated a spectrometer with a 3.5 wavelength lateral footprint.

Main Results:

• Achieved a spectral resolution of 10 nm in the mid-infrared band (3590-3760 nm).
• Demonstrated highly decorrelated spectral responses, theoretically optimal for minimizing noise-induced error.
• The spectrometer is suitable for molecular sensing applications.

Conclusions:

• The developed spectrometer offers a miniaturized, noise-resistant solution for on-chip sensing.
• The design is extensible to other spectral bands, enabling lab-on-a-chip devices and chemical sensors.