Topological Darkness in Optical Heterostructures: Prediction and Confirmation

Area of Science:

• Photonics and optical physics
• Condensed matter physics
• Materials science

Background:

• Topological darkness is a novel optical phenomenon characterized by complete light absorption or zero reflection/transmission.
• It is associated with topologically nontrivial phase singularities, offering unique optical properties.
• Understanding and predicting topological darkness is crucial for developing advanced optical devices.

Purpose of the Study:

• To propose and validate an algorithm for predicting and confirming topological darkness in optical heterostructures.
• To investigate the occurrence of topological darkness in ultrathin palladium (Pd) films on a composite substrate.
• To demonstrate the utility of this phenomenon in topological photonics and biosensing.

Main Methods:

• Development of an algorithm combining optical measurements with Fresnel equations.
• Fabrication of ultrathin Pd films on a silicon/silicon dioxide/chromium (Si/SiO2/Cr) substrate.
• Application of the algorithm to experimental data to identify points of topological darkness.

Main Results:

• The study successfully identified four distinct points of topological darkness in the ultrathin Pd films.
• The proposed algorithm effectively predicts and confirms the presence of topological darkness.
• Experimental validation was achieved using a specific heterostructure configuration.

Conclusions:

• The developed algorithm provides a reliable method for detecting topological darkness.
• The findings pave the way for novel applications in topological photonics.
• This research contributes to the advancement of label-free optical biosensing through phase interrogation.