A novel approach to Fabry\u2013P\xe9rot-resonance-based lens and demonstrating deep-subwavelength imaging

Md. Anzan-Uz-Zaman,Shin Hur,Duck-Gyu Lee,Kyungjun Song

doi:10.1038/s41598-020-67409-4

Md. Anzan-Uz-Zaman, Shin Hur + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-67409-4

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Abstract

During our research, we explored a novel way to represent subwavelength imaging and derived a transmission equation to explicate the FP (Fabry–Pérot) resonance phenomena. Subsequently, using analysis and observation, we performed deep-subwavelength imaging. Both numerically and experimentally, imaging with super-resolution was achieved at deep subwavelength scale of λ/56.53 with a lens thickness 212 mm. Our results also showed that by increasing lens thickness, higher resolution can be achieved. Moreover, via a single source study, we showed the full width at half maximum range and predicted the size of smallest detectable object. We also observed that with a greater lens thickness, finer features could be detected. These findings may open a new route in near-field imaging for practical applications such as biometric sensors, ultrasonic medical equipment, and non-destructive testing.

Highlights

During our research, we explored a novel way to represent subwavelength imaging and derived a transmission equation to explicate the FP (Fabry–Pérot) resonance phenomena
In 1873, Ernst Abbe made an observation that the minimum resolvable distance for a wave is /(2NA), where NA is the numerical aperture, which is equal to n · sin θ1
Several other reports[11,12,13,14,15,16] can be found on using a negative index material (NIM), an ɛ-negative material (ENG), or a μ-negative material (MNG) to overcome the diffraction limit for electromagnetic waves. These reports show that a NIM is not an essential condition for achieving subwavelength imaging

Summary

Introduction

We explored a novel way to represent subwavelength imaging and derived a transmission equation to explicate the FP (Fabry–Pérot) resonance phenomena. In the year of 2011, Zhu et al.[37] provided the eminent transmission equation using the resemblance of acoustic wave to light through 1D slit and demonstrated deep-subwavelength imaging with the highest resolution of λ/50 by creating a highly anisotropic medium and using Fabry–Pérot (FP) resonance. Due to the dependence on thickness, the lens becomes bulky for low-frequency imaging To overcome this, another type of anisotropic acoustic metamaterial has been reported based on the resonant tunneling m ethod[38,39,40]. In present paper, unlike the conventional theory[37], we used a novel approach named as three-medium model which is not adapted from the EM counterpart, rather from acoustic regime and, may provide a fresh perspective to derive the transmission equation of FP-resonance-based lens. We hope that the findings presented here will facilitate researchers to apply the lens for practical purposes

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