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Excitons Enabled Topological Phase Singularity in a Single Atomic Layer.

Guoteng Ma1, Wanfu Shen1,2, Daniel Soy Sanchez1

  • 1State Key Laboratory of Precision Measuring Technology and Instruments, School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.

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|September 11, 2023
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Summary
This summary is machine-generated.

Researchers demonstrate topologically protected phase singularities (PSs) in single-atom layers of transition metal dichalcogenide (TMDC) monolayers. These PSs enable ultra-thin, highly sensitive biosensors for refractive index detection and bacteria identification.

Keywords:
excitonslabel-free biosensorsmonolayerphase singularitytopological zero-reflectiontransition metal dichalcogenides

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Area of Science:

  • Condensed Matter Physics
  • Photonics
  • Nanotechnology

Background:

  • Phase singularities (PSs) exhibit unique Heaviside phase jump behavior, crucial for topological modes in condensed matter physics.
  • Applications in photonics and ultrasensitive sensors highlight the importance of PSs.
  • Exciton resonances in materials offer potential for generating novel topological phenomena.

Purpose of the Study:

  • To demonstrate the universal existence of topologically protected PSs in single-atom layers.
  • To explore the use of transition metal dichalcogenide (TMDC) monolayers for generating these PSs.
  • To investigate the application of TMDC-based PSs in refractive index biosensing.

Main Methods:

  • Coating TMDC monolayers on a nonabsorptive semi-infinite substrate.
  • Utilizing exciton resonances for PS generation without plasmonic or resonator assistance.
  • Employing refractive index matching for transparent substrates.

Main Results:

  • Achieved topologically protected PSs in single-atom-layer TMDC monolayers.
  • Demonstrated zero reflection and a perfect Heaviside π-phase jump at strong light absorptions.
  • Developed TMDC monolayer-based PSs exhibiting high phase sensitivity (10^4 degrees/RIU) for biosensing, including bacteria detection.

Conclusions:

  • TMDC monolayers provide a platform for creating ultra-thin, topologically protected PS devices.
  • The developed PSs offer a novel approach for flat singular optics.
  • This work paves the way for advanced label-free biosensing technologies with single-atomic-layer sensitivity.