Sub-Nanowatt Sensitivity MMI Spectrometers With Elevated Scattering Regions

We report the design of a miniaturized spectrometer based on Multi Mode Interference (MMI waveguides) with an elevated Scattering Region (ESR) that addresses the shortcomings of previous designs by incorporating a layered waveguide structure that significantly reduces light loss at critical transition junctions. The ESR design yields a marked improvement in the signal-to-noise ratio (SNR) and maintained measurable SNR values even at extremely low input powers down to 32 picowatts at a wavelength range of 620-670 nm. By integrating these design enhancements with a previously designed machine-learning algorithm trained to recognize and analyze scattering patterns, we have expanded potential applications for spectrometer miniaturization and performance.