Study explores topological teleportation of light

Far-field properties of light from isotropic light sources near the topological junction metasurface. (A) Far-field radiation pattern from a series of isotropic emitters evenly located inside the device region from x = −5 to 5 μm at z = 0 |Ey|2. (B and C) Normalized localization envelope function f( x) and spatial Fourier transform F(kx) for emission angle θ in empty space. (D) Position-wave vector uncertainty relationship of the leaky JR state with respect to the bandgap dimension g. Credit: Science Advancesdoi: 10.1126/sciadv.add8349

Nanophotonic light emitters are compact and versatile devices with far-reaching applications in applied physics. In a new report released now Science AdvancesKi Young Lee and a physics and engineering research team in China and the UK have proposed developing a high efficiency topological beam emitter structure with adaptive beamforming capability, submicron footprint size.

The proposed device facilitated a highly desirable and efficient microlight emitter for sensing a variety of applications including displays, solid-state light sensing, optical interconnects, and telecommunications.

Photonic topological phenomena

Topological interface states have extremely high robustness to environmental disturbances with unique physical properties. Many researchers in the fields of mathematics and photonics have extensively investigated photonic topological phenomena because of their promise in telecommunications, data processing and sensor applications.

In this work, Lee and colleagues investigated novel far-field optical properties associated with non-Hermitian topological photonics. They demonstrated how a topological coupling metasurface of two guided-mode resonance gratings can serve as efficient submicron-scale light emitters with high quantum efficiency and adaptive beamforming capability.

During the experiments, the team used a junction containing two different guided-mode resonance gratings directly adjacent to each other in the absence of an aperture. Leaky Jackiw-Rebbi (JR) condition at the port in such builds; This corresponds to a historically important model of relativity – it emits a narrow beam of light. The process was driven by cavity-quantum electrodynamic coupling and electromagnetic funneling effects. The team investigated a basic topological theory of beam emission and performed rigorous numerical analyzes during the study.

Topolojik ışık hüzmesiScience Advancesdoi: 10.1126/sciadv.add8349″/>

Key features of the leaky JR state in a topological link metasurface. (A) Diagram of a topological connection consisting of two different thin-film subwavelength gratings. (B) Angle dependent reflection spectra for the left unit cell in topological phase (left), right unit cell in trivial phase (right), and junction points (middle). (C) λJR = electric field amplitude of the leaky JR state at a wavelength of 633 nm, Ey. We use the finite element method (Comsol Multiphysics) for this calculation. Credit: Science Advancesdoi: 10.1126/sciadv.add8349

Leakage radiation from the Jackiw-Rebbi (JR) state

Lee et al. investigated the leaky JR state localized on a photonic topological junction metasurface, in which the structure retains a high-index film. Under certain conditions, first-order diffraction from the JR state led to beam leakage radiation towards the surrounding background, collecting the characteristic features of stray radiation during operation.

Based on the narrow beam emission associated with the leaky JR state, the team investigated the emission characteristics of light sources near the topological junction. They used the finite element method to calculate the radiation pattern showing a narrow beam propagating in the optical far field. The team then explained the possibility of designing a suitable structure where the two grating regions would have the same Dirac mass to achieve the ideal symmetry of the emitted beam.

During these experiments, narrow beam emission from isotropic light sources followed the exact diffraction characteristics of radiation leakage from the JR state. The team also evaluated external sources for the proposed irradiation effect, which they achieved by introducing modifications to the experimental setup, including a reduced index contrast and vertically coupled multilayer waveguides, among other modifications.

Topolojik ışık hüzmesiScience Advancesdoi: 10.1126/sciadv.add8349″/>

Purcell enhancement of electromagnetic funnel and internal sources. (A) Optical power flow (time-averaged Poynting vector 〈S〉t; red arrows) distribution for a topological junction with a bandgap size g = 40 nm relative to the near-field density distribution (gray level density). (B and C) Optical power flux (xP = 1 and 2 µm) induced by a single isotropic source at 1 and 2 µm from the junction. (D) Source location (xP) dependent far-field intensity distribution in an observation plane 3.5 μm above the grating surface as a function of xP. (E) Purcell factor distribution compared to the near-field intensity distribution associated with JR status. Credit: Science Advancesdoi: 10.1126/sciadv.add8349

Topolojik ışık hüzmesiScience Advancesdoi: 10.1126/sciadv.add8349″/>

Flat top beam generation with Dirac mass control. (A) Dirac mass m(x) distribution for flat top beam production. m′ = −0.634 has three plateaus at 0 and +0.635 μm−1, and the associated JR state intensity profiles and radiated beam profiles are plotted together as a reference. (B) Electric field density |Ey|2 model from the structure design based on the Dirac mass distribution in (A). The device structure in this simulation has three grid regions with different fill factors at F=0.264, 0.46 and 0.7, corresponding to the three Dirac mass plateaus. Credit: Science Advancesdoi: 10.1126/sciadv.add8349

adaptive beamforming

The concept of beamforming is important to many general applications of light sources. The described topological teleportation effect provides the possibility to edit the beamform directly from the source. The scientists explained the Dirac mass distribution needed to create the expected beam profile.

For example, to create a flat top beam, the zero Dirac mass region can be extended along the desired width and around the attachment point of the device. The results of guided-mode resonance Dirac mass regulation can efficiently facilitate beamforming applications.


In this way, Ki Young Lee and colleagues proposed a topological coupling metasurface for efficient beam emission. By integrating junction-quantum electrodynamics coupling with electromagnetic funneling effects, they simulated the characteristic field distributions of a leaky Jackiw-Rabbi state at the junction to obtain efficient light beams from internal emitters.

The proposed architecture is important for the creation of efficient microlight emitters for strong localization, high quantum efficiency, and adaptive beamforming capability. These properties are important for numerous applications, including the development of image pixels, laser processing and telecommunications applications. The proposed devices are also capable, in principle, of acting as efficient optical detectors due to their scope to act as time-reversed emitters. The scientists suggest further optimization of the study results to develop new optical effects and companion device applications to overcome current technical limits.

More information:
Ki Young Lee et al., Topological light beam, Science Advances (2022). DOI: 10.1126/sciadv.add8349

Alexander Cerjan et al., Experimental realization of the Weyl exceptional ring, Nature Photonics (2019). DOI: 10.1038/s41566-019-0453-z

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