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Miniature spectrometers are in high demand for portable optical sensing, on-chip systems, and other consumer applications, due to their small size and light weight. Recently, on-chip spectrometers, which are based on simple hardware systems, and recover unknown spectra by reconstruction algorithms, have become one of the most important research trends. Such on-chip computational spectrometers typically employ random spectral filters such as quantum dot arrays, photonic crystal arrays, and so on. However, these random spectral filters generally need expensive materials or complex preparation processes. So, the low-cost and easy-to-prepare spectral filters are pursued in developing computational spectrometers. Here we report the on-chip spectrometer using polarization-responsive filters, which are directly placed on top of a CMOS sensor. These spectral filters contain birefringent material and two polarizers and generate different transmittance spectra by the complex optical interference of them with different polarization angles. We verified the validity of this approach by simulation. This spectrometer only uses polarizers, micas, and a CMOS sensor, and has the advantages of low cost, simple preparation, and small footprint.
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