Dual-Phase Singularity at a Single Incident Angle with Spectral Tunability in Tamm Cavities

Area of Science:

• Nanophotonics
• Plasmonics
• Optical Sensing

Background:

• Phase singularity, a sudden phase change at reflection zero, is typically observed at large incident angles (>50 degrees) in nanophotonic systems.
• Achieving multiple phase singularities at a single incident angle is a significant challenge in optical research.

Purpose of the Study:

• To experimentally demonstrate dual-phase singularity at lower incident angles.
• To explore the potential of a tunable Tamm plasmon polariton (TPP) cavity for achieving dual-phase singularity.
• To propose a TPP cavity-based hydrogen sensor and investigate the impact of dual-phase singularity on sensing sensitivity.

Main Methods:

• Fabrication of a tunable TPP cavity using a gold-coated ultralow-loss phase change material Sb2S3-based distributed Bragg reflector.
• Excitation of narrowband TPP resonances for both s- and p-polarizations across a wide range of incident angles.
• Experimental demonstration of dual-phase singularity at lower incident angles due to differing zero-reflection wavelengths for s- and p-polarized TPP resonances.
• Proposal and analysis of a TPP cavity-based hydrogen sensor.

Main Results:

• Experimental confirmation of dual-phase singularity at lower incident angles using the developed TPP cavity.
• Observation of narrowband TPP resonances from normal to wide angles of incidence for both s- and p-polarizations.
• Demonstration of improved sensitivity in a proposed hydrogen sensor utilizing dual-phase singularity.
• Experimental realization of spectrally tunable dual-phase singularity at lower incident angles in a metal-free Tamm cavity.

Conclusions:

• The tunable TPP cavity enables dual-phase singularity at lower incident angles, overcoming previous limitations.
• Dual-phase singularity offers enhanced sensitivity for singular phase-based sensing applications, as demonstrated with a hydrogen sensor.
• The development of spectrally tunable dual-phase singularity in metal-free cavities broadens the applicability of this phenomenon.