Frequency tunable coherent perfect absorption and lasing in radio-frequency system for ultrahigh-sensitive sensing

Abstract

A coherent perfect absorption-lasing (CPAL) point in non-Hermitian physics systems has infinite output amplitudes (or quality factor) theoretically and has been utilized for applications. However, practical implementation of CPAL systems faces extreme challenges because of the deviations of electronic components from ideal values, which makes it difficult to attain the CPAL state. Moreover, the amplitude-based output is easily interfered by noises or environments and is inferior as compared to frequency shift-based sensing. Through the investigation of the effects of component deviations on general CPAL systems, we propose an eigenstate tuning method specifically tailored for radio-frequency (RF) CPAL systems. The method enables the realization of CPAL states at any desired frequency with dynamic ranges of signal amplitudes exceeding 60 dB experimentally or to work at a frequency shift-based sensing. Then, a CPAL-based RF sensor system is developed for verification, showing an ultrahigh sensitivity of 1.9 dB/10 fF by measuring output coefficient variation or 9.4 MHz/pF by measuring frequency shift, significantly broadening the application scope of CPAL systems.