This impetus has led to the rapid development of miniatured spectrometers implemented on metasurfaces 6, micro-opto-electro-mechanical systems (MOEMS) 7, and photonic integrated circuits (PIC) 8, 9, 10. There is an ever-growing demand for portable, handheld, and even wearable spectrometers in many emerging applications, such as intelligent health monitoring 4 and portable optical coherent tomography 5. Nevertheless, the extensive use of benchtop spectrometers for in situ measurements is severely limited by their bulky sizes, sensitivity to platform vibration, and relatively high power consumption. Conventional benchtop spectrometers, which rely on dispersive gratings or movable components, can provide high spectral resolutions and broad working bandwidths under the laboratory condition. The optical spectrometer has been utilized as a potent analytical tool in many scientific and industrial applications, including but not limited to material characterization 1, medical imaging 2, and remote environmental monitoring 3. Spectrometry is the technology for detecting intensity information in the spectral domain. An ultralarge wavelength-channel capacity of 2501 is supported by a single spatial channel within an ultrasmall footprint (≈60 × 60 μm 2), which represents, to the best of our knowledge, the highest channel-to-footprint ratio (≈0.69 μm −2) and spectral-to-spatial ratio (>2501) ever demonstrated to date. An ultrahigh resolution of 100 nm far exceeding the narrow FSR. Experimental results demonstrate that this approach can resolve any arbitrary spectra with discrete, continuous, or hybrid features. Thus, unknown input spectra can be retrieved by solving a linear inverse problem with iterative optimizations. Fourier analysis reveals that each left singular vector of the transmission matrix is mapped to a unique frequency component of the recorded output signal with a high sideband suppression ratio. When tuning over a single FSR, each wavelength channel is encoded with a unique scanning trace, which enables the decorrelation over the whole bandwidth spanning multiple FSRs. We tailor the dispersion of mode splitting in a photonic molecule to identify the spectral information at different FSRs. In this paper, we propose and demonstrate a ground-breaking spectrometer design beyond the resolution-bandwidth limit. Typically, a high resolution requires long optical paths, which in turn reduces the free-spectral range (FSR). ![]() ![]() ![]() The miniaturization of integrated spectrometers faces the challenge of an inherent trade-off between spectral resolutions and working bandwidths. The chip-scale integration of optical spectrometers may offer new opportunities for in situ bio-chemical analysis, remote sensing, and intelligent health care.
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