“…As a selection of alternatives to these mini grating spectrometers, we compare in this review paper four strongly miniaturized optical spectrometers ( Table 1 ): AWG devices [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ], static FP filter arrays on a charge-coupled device (CCD) or complementary metal oxide semiconductor (CMOS) sensor arrays [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ], tunable MEMS FP filter arrays [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ] on photodetector (PD) arrays, and tunable MEMS photonic crystal (PC) filters [ 61 , 70 , 71 , 72 , 73 , 74 ]. At first glance, we identify that all these alternatives are smaller in size and reveal higher resolutions, as well as smaller FWHM than the grating spectrometers.…”