Loss-induced phase transition in mid-infrared plasmonic metamaterials for ultrasensitive vibrational spectroscopy

Abstract

Metamaterials have proven their ability to possess extraordinary physical properties distinct from naturally available materials, leading to exciting sensing functionalities and applications. However, metamaterial-based sensing applications suffer from severe performance limitations due to noise interference and design constraints. Here, we propose a dual-phase strategy that leverages loss-induced different Fano-resonant phases to access both destructive and constructive signals of molecular vibration. When the two reverse signals are innovatively combined, the noise in the detection system is effectively suppressed, thereby breaking through the noise-related limitations. Additionally, by utilizing loss optimization of the plasmon-molecule coupling system, our dual-phase strategy enhances the efficiency of infrared energy transfer into the molecule without any additional fabrication complex, thereby overcoming the trade-off dilemma between performance and fabrication cost. Thanks to the pioneering breakthroughs in the limitations, our dual-phase strategy possesses an overwhelming competitive advantage in ultrasensitive vibrational spectroscopy over traditional metamaterial technology, including strong signal strength (×4), high sensitivity (×4.2), effective noise suppression (30%), low detection limit (13 ppm), and excellent selectivity among CO2, NH3, and CH4 mixtures. This work not only opens the door to various emerging ultrasensitive detection applications, including ultrasensitive in-breath diagnostics and high-information analysis of molecular information in dynamic reactions, but also gains new insights into the plasmon-molecule interactions in advanced metamaterials. (Figure presented.).