Compact photonic crystal spectrometer with resolution beyond the fabrication precision

We present a compact silicon photonic crystal spectrometer with a footprint of 740 × 9 µm² and excellent wavelength resolution (∼0.01 nm at single and <0.03 nm at multiple wavelength operation) across a telecom bandwidth of 10 nm. Although our design targets a wavelength resolution of 1.6 nm, within the current state-of-the-art fabrication precision of 2 nm, we achieve a resolution that exceeds these limits. This enhanced resolution is made possible by leveraging the random localization of light within the device.