Strategies for high performance and scalable on-chip spectrometers

Miniature spectrometers provide promising potential for on-chip or in situ optical analysis. In recent years there has been significant progress towards reducing the size and improving the performance of these spectrometers. The workhorse is light splitting components. This work has been led primarily by the innovative use of new light analysis strategies and new nanostructured materials with the notable increase in the spectral range and resolution. This review summarizes the latest developments classified as monochromatic, modulated and computational types of miniature spectrometers according to the spectral extraction methods. Particularly, we highlight the recent advances in designing of sophisticated gratings, resonators, interferometers and photonic crystals (PCs), the emerging of novel nanostructured materials and improvement in the computational spectra reconstruction algorithms. We examine the different approaches employed to reduce size and enhance light-matter interaction of the final spectrometers, especially emphasizing the trade-off between various metrics of the spectrometer including device footprint, measurable spectral range, spectral resolution, sensitivity as well as complementary metal oxide semiconductor compatibility. We also examine potential applications of on-chip spectrometers and outlook where further developments are required.