“…However, the development of on-chip spectrometers based on photonic integrated circuits (PICs) has shown great promise in the sense that they can offer low-cost, portable, and robust spectroscopy, along with low power consumption and high reliability . In recent decades, a myriad of on-chip spectrometer devices have been demonstrated based on different operating schemes, such as dispersive optics using arrayed waveguide gratings (AWGs), − echelle grating, metasurface elements, arrayed narrow-band filters, computational spectral reconstruction-based systems, and Fourier transform spectroscopy (FTS). Dispersive spectrometers, often called grating spectrometers or scanning spectroscopy, splits the wavelengths of input light into separate spectral ranges and collects each wavelength individually.…”