Reconfigurable sensor can detect particles 0.001 times the wavelength of light

In recent years, advances in photonics and materials science have led to remarkable breakthroughs in sensor technology, pushing the boundaries of what can be detected and measured. Among these innovations, non-Hermitian physics has emerged as a crucial area of ​​research, offering new ways to manipulate light and improve the sensitivity of sensors.

A recent study published in Advanced Photonic Nexus reports a breakthrough in this area, presenting a new type of sensor that exploits exceptional points (EP) to achieve unprecedented levels of sensitivity.

This study presents a highly sensitive and reconfigurable sensor based on a unique localized surface plasmon (LSP) resonator. The exceptional points are unique spectral singularities where the eigenvalues ​​and their corresponding eigenvectors converge, significantly increasing the sensitivity of optical sensors.

Traditional EP-based sensors, such as whispered gallery mode (WGM) microtoroids, have demonstrated increased sensitivity over conventional sensors. However, these sensors face limitations: their EPs are fixed after manufacturing, making fine adjustments difficult, and they often operate in a narrow frequency range, struggling to detect very small particles due to constraints in perturbation force and excitation efficiency.

The new sensor design addresses these issues by integrating spoofed LSP resonators, which simulate the behavior of localized surface plasmons and provide greater flexibility. Suspended above a microstrip line and coupled with two movable Rayleigh scatterers, this configuration allows dynamic reconfiguration of EP states over a wide frequency range. This adaptability makes the sensor more robust to manufacturing imperfections and improves its ability to detect extremely small particles.

The main features of the new sensor are:

• Reconfigurability: Tunable Rayleigh scatterers enable dynamic shaping and reconfiguration of EPs, improving sensor accuracy and flexibility.

• Improved perturbation strength: Confining electromagnetic fields to the resonator surface significantly increases sensitivity to perturbations from surrounding particles.

• Multipole mode excitation: The design supports various plasmon resonance modes, expanding the operational bandwidth and detection range of the sensor.

This advancement represents a significant leap forward in sensor technology, delivering exceptional sensitivity to detect particles as small as 0.001 times the wavelength of light and opening up new possibilities for applications in scientific research and industry.