Breaking the resolution-bandwidth limit of chip-scale spectrometry by harnessing a dispersion-engineered photonic molecule  

作　　者：Hongnan Xu Yue Qin Gaolei Hu Hon Ki Tsang 

机构地区：[1]Department of Electronic Engineering,The Chinese University of Hong Kong,Shatin,New Territories,Hong Kong SAR,China

出　　处：《Light(Science & Applications)》2023年第3期475-488,共14页光（科学与应用)（英文版）

基　　金：Innovation and Technology Fund(MRP/066/20).

摘　　要：The chip-scale integration of optical spectrometers may offer new opportunities for in situ bio-chemical analysis,remote sensing,and intelligent health care.The miniaturization of integrated spectrometers faces the challenge of an inherent trade-off between spectral resolutions and working bandwidths.Typically,a high resolution requires long optical paths,which in turn reduces the free-spectral range(FSR).In this paper,we propose and demonstrate a ground-breaking spectrometer design beyond the resolution-bandwidth limit.We tailor the dispersion of mode splitting in a photonic molecule to identify the spectral information at different FSRs.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.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.Thus,unknown input spectra can be retrieved by solving a linear inverse problem with iterative optimizations.Experimental results demonstrate that this approach can resolve any arbitrary spectra with discrete,continuous,or hybrid features.An ultrahigh resolution of<40 pm is achieved throughout an ultrabroad bandwidth of>100 nm far exceeding the narrow FSR.An ultralarge wavelength-channel capacity of 2501 is supported by a single spatial channel within an ultrasmall footprint(≈60×60μm^(2)),which represents,to the best of our knowledge,the highest channel-to-footprint ratio(≈0.69μm^(−2))and spectral-to-spatial ratio(>2501)ever demonstrated to date.

关 键 词：RESOLUTION dispersion LIMIT 

分 类 号：O657.3[理学—分析化学]