# Cavity enhanced terahertz fingerprint detection with ultrahigh sensitivity

## TL;DR

This paper introduces a cavity-enhanced terahertz detection scheme that significantly improves sensitivity for fingerprint identification, achieving detection of nanometer-scale samples with high precision.

## Contribution

The novel cavity-based approach amplifies terahertz transmission decay, enabling ultrahigh sensitivity detection of substances like { extalpha}-lactose at sub-wavelength scales.

## Key findings

- Detection sensitivity is 500 times higher than traditional methods.
- Successfully detected 7nm { extalpha}-lactose, 1/80000 of the wavelength.
- Scheme retains substance identification capabilities.

## Abstract

We report a new scheme of realizing terahertz fingerprint detection with ultrahigh sensitivity. Instead of using the direct absorption of terahertz through a bare sample in the regular transmission scheme, a cavity mode resonating at the characteristic frequency of the sample is used and due to the high dependence of the cavity mode transmission on the material loss, an amplified transmission decaying is observed when the sample is loaded into the cavity. Furthermore, this scheme retains the feature of substance identification. A one-dimensional photonic crystal cavity is used as the example for the detection of {\alpha}-lactose and an efficient detection of 7nm {\alpha}-lactose can be achieved, which corresponds to 1/80000 of the free space wavelength at the characteristic frequency of 0.529THz, exhibiting sensitivity 500 times higher than the regular method.

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Source: https://tomesphere.com/paper/1706.01976