Appl. Phys. Lett. 100, 231104 (2012)
Scientists in Germany and the USA have fabricated a miniature high-resolution spectrometer based on a planar array of GaP photonic crystal cavities. Each cavity outcouples light of a specific resonant wavelength to a photodetector, thus allowing the spectral signature of incoming light in a waveguide to be determined. Although this proof-of-principle device is based on a 3 × 3 or 10 × 10 array of cavities, scaling the design to match a megapixel detector array should be possible, allowing millions of wavelength channels to be monitored simultaneously. The device operates in the near-infrared around 840 nm and has a resolution of 0.3 nm. However, the researchers say that improving the fabrication quality should provide an order of magnitude increase in resolution. The design could also be extended to operation in either the visible or deep-infrared. The absence of any moving parts and the small size of the device (each photonic crystal cavity has lateral dimensions of just a few micrometres) means that it could be appealing as a tool for convenient chemical and biological analysis.
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Graydon, O. Spectrometer success. Nature Photon 6, 501 (2012). https://doi.org/10.1038/nphoton.2012.200