High-Precise Measurement of Optical Rotatory Dispersion Based on Weak Value Amplification

Jingyi Shao,Zhiyou Zhang,Yurong Liu,Jiacheng You,Yuyuan Wang,Yu He,Lan Luo

doi:10.1109/jphot.2021.3094588

Abstract

Chiroptical signals (generally very weak) play significant roles in chiral discrimination that bring great benefits in biochemistry, pharmacy, chemical, and so on. But, high-precise chiroptical detection is still a challenge. In this paper, a high-precise measurement of optical rotatory dispersion (ORD) based on weak value amplification (WVA) is presented. We proposed ORD detection method with parameter separation: by introducing complex coupling strength and dimensionless parameter “intensitiy contrast ratio” pointer, the ORD is only associated with the imaginary part of the weak value while circular dichroism (CD) is only associated with the real part. By designing a suitable WVA scheme, the ORD and CD can be measured separately. In the experiment, the reliability of the parameter separation method for ORD measurement is verified, and the precision reach the order of $10^{-6}$ rad. This method has a broad application prospect in biomedical sensing, medicine, chemical analysis and other fields.

Highlights

Chiral molecules, whose mirror images cannot coincide with themselves, always play a significant role in biochemistry, pharmacy, and so on
Qiu et al proposed a precision method based on weak measurements using the spin Hall effect of light (SHEL) as a probe, and the optical rotatory (OR) angle can be estimated with a precision of 0.2 mdeg[41]
We proposed a parameter separation method based on weak value amplification (WVA) for chiroptical signals detection: by introducing complex coupling strength and dimensionless parameter ”intensitiy contrast ratio (ICR)” pointer, the optical rotatory dispersion (ORD) is only associated with the imaginary part of the weak value while circular dichroism (CD) signal is only associated with the real part by designing a suitable WVA scheme, the ORD and CD can be measured separately

Summary

Introduction

Chiral molecules, whose mirror images cannot coincide with themselves, always play a significant role in biochemistry, pharmacy, and so on. Existing optical methods for detecting the chiral molecules, such as force chemical microscopy[1], chromatography[2], piezoelectric sensors[3], and fluorescence[4], have their limitations. Qiu et al proposed a precision method based on weak measurements using the spin Hall effect of light (SHEL) as a probe, and the optical rotatory (OR) angle can be estimated with a precision of 0.2 mdeg[41]. We proposed a parameter separation method based on WVA for chiroptical signals detection: by introducing complex coupling strength and dimensionless parameter ”intensitiy contrast ratio (ICR)” pointer, the ORD is only associated with the imaginary part of the weak value while CD signal is only associated with the real part by designing a suitable WVA scheme, the ORD and CD can be measured separately. The reliability of parameter separation for ORD measurement is verified, and the precision reach the order of 10−6 rad

Theoretical Model

The Experimental Results

Conclusions