Magnetic-dipolar-mode Fano resonances for microwave spectroscopy of high absorption matter

TL;DR

This paper introduces a novel microwave sensing method utilizing magnetic-dipolar-mode Fano resonances to accurately characterize high-absorption biological liquids, overcoming limitations of traditional resonant techniques.

Contribution

It presents an innovative approach combining microwave perturbation and Fano resonance effects with magnetic-dipolar quantum dots for high-absorption material spectroscopy.

Findings

Achieved precise measurement of high-loss liquids' resonant frequencies.

Demonstrated narrow Lorentzian peaks enable accurate characterization.

Applicable to biological liquids with high absorption.

Abstract

Study of interaction between high absorption matter and microwave radiated energy is a subject of great importance. Especially, this concerns microwave spectroscopic characterization of biological liquids. Use of effective testing methods to obtain information about physical properties of different liquids on the molecular level is one of the most important problems in biophysics. However, the standard methods based on the microwave resonant techniques are not sufficiently suitable for biological liquids because the resonance peak in a resonator with high-loss liquids is so broad that the material parameters cannot be measured correctly. Although molecular vibrations of biomolecules may have microwave frequencies, it is not thought that such resonant coupling is significant due to their low energy compared with thermal energy and the strongly dampening aqueous environment. This paper presents an innovative microwave sensing technique for different types of lossy materials, including biological liquids. The technique is based on the combination of the microwave perturbation method and the Fano-resonance effects observed recently in microwave structures with embedded magnetic-dipolar quantum dots. When frequency of the magnetic-dipolar-mode (MDM) resonance is not equal to the cavity resonance frequency, one gets Fano transmission intensity. With tuning, by a bias magnetic field, the MDM resonance frequency to the cavity resonance frequency, one observes a Lorentz line shape. Use of an extremely narrow Lorentzian peak allows exact probing the resonant frequency of a cavity loaded by a high-lossy-material sample. For different kinds of samples, one has different frequencies of Lorentzian peaks. This gives a picture for precise spectroscopic characterization of high absorption matter in microwaves.