Ultrasensitive refractive index sensor with rotatory biased weak measurement

TL;DR

This paper introduces a rotatory biased weak measurement technique that significantly enhances the sensitivity and resolution of refractive index sensors, achieving an optimal resolution of 4×10⁻⁷ RIU and demonstrating high responsiveness in biological detection.

Contribution

The paper proposes a novel rotatory biased weak measurement scheme that improves refractive index sensor sensitivity and resolution beyond standard methods.

Findings

Achieved an enhanced refractive index sensitivity of 13605 nm/RIU.

Demonstrated an optimal refractive index resolution of 4×10⁻⁷ RIU.

Validated high response to IgG concentration with a detection limit of 15 ng/mL.

Abstract

A modified weak measurement scheme, rotatory biased weak measurement, is proposed to significantly improve the sensitivity and resolution of the refractive index sensor on a total reflection structure. This method introduces an additional phase in the post-selected procedure and generates an extinction point in the spectrum distribution. The biased post-selection makes smaller coupling strength available, which leads to an enhancement of phase sensitivity and refractive index sensitivity. In rotatory biased weak measurement, we achieve an enhanced refractive index sensitivity of 13605 nm/RIU compared to 1644 nm/RIU in standard weak measurement. The performance of sensors with different sensitivity is analyzed, and we find the optimal refractive index resolution of sensors increases with sensitivity. In this work, we demonstrate an optimal refractive index resolution of $4\times10^{-7}$ RIU on a total reflection structure. The rabbit anti-mouse IgG and mouse IgG binding reaction experiments demonstrate that our system has a high response to the concentration of IgG in a wide range and the limit of detection is 15 ng/mL. The improvements in this work are helpful to the optimizations of other optical sensors with weak measurement.