Tuning and switching effects of quasi-BIC states combining phase change materials with all-dielectric metasurfaces

Abstract

Emission enhancement of quantum emitters is particularly relevant in the development of single-photon sources, which are key elements in quantum information and quantum communications. All-dielectric metasurfaces offer a route towards strong enhancement of local density of optical states via engineering of high quality factor optical modes. In particular, the recently proposed concept of quasi-bound states in the continuum (quasi-BIC) allows for precise control of such resonances in lattices with an asymmetric unit cell. Still, the spectral band of emission enhancement is usually fixed by the geometric parameters of the metasurface. Here, we propose to utilize phase change materials to tune the properties of light-emitting metasurfaces designed to support quasi-BIC states in the telecom wavelength range. In our design, a thin layer of a phase change material, which provides strong contrast of refractive index when switched from the amorphous to the crystalline state, is located on top of the resonators made of amorphous silicon (a-Si). Depending on the selected phase change material, we numerically demonstrate different functionalities of the metasurface, In particular, for low-loss Sb2Se3 we evidence spectral tuning effects, whereas for Ge2Sb2Te5, we report an “on”/“off” switching effect of the quasi-BIC resonance. Furthermore, we investigate the influence of the crystallization fraction and the asymmetry parameter of the metasurface on the results. This work provides concrete design blueprints for switchable metasurfaces, offering new opportunities for nanophotonics devices or integrated photonic circuits.

Real-time monitoring of polarization state deviations with dielectric metasurfaces

“…33 Furthermore, one can also employ various physical mechanisms to tune the metasurface transmission, 34 for example, using liquid crystals 35 or phase-change materials in combination with quasi-bound state in continuum (quasi-BIC) resonances. 36,37 We anticipate that our work will support the development of a new class of ultracompact and ultrasensitive flat meta-optical devices for a broad range of applications, including advanced sensing, imaging, and metrology in both classical and quantum photonics.…”

“…In the future, tilting the metasurface could serve as additional possibility to tune the polarization transformations 33 . Furthermore, one can also employ various physical mechanisms to tune the metasurface transmission, 34 for example, using liquid crystals 35 or phase-change materials in combination with quasi-bound state in continuum (quasi-BIC) resonances 36 , 37 …”

Phase‐Change Perovskite Microlaser with Tunable Polarization Vortex

“…Recent realizations of BIC modulation via electrical, optical, or acoustical signals have been limited to on-off state switching or wavelength tuning of the state. [1,[6][7][8][9][10][11] Dynamic switching between BICs with different topological charges, a degree of freedom not yet unlocked, would offer new opportunities for switchable metasurfaces, integrated active nanophotonic devices, and tunable vector beams.…”

“…Functional metasurfaces relying on phase-change media like chalcogenides, [10][11][12][13][14] metal-oxides, [15] and liquid crystals [9,16] offer solutions for dynamically tunable devices in a compact footprint. [17] However, while conventional phase-change media are widely exploited in passive reflective and transmissive devices, they are not suitable for active light emitting devices like lasers, due to the lack of optical gain.…”

Tunable High-Q Resonance Based on Hybrid Phase-Change Metasurfaces

“…In particular, the refractive index of GST makes a large change through the phase transition. Based on the variation in the refractive index, GST has been combined with metasurfaces to generate numerous tunable optical devices. − Recently, a few studies have demonstrated the tunable BICs by combining metasurfaces with semiconductor or polymer . However, the wavelength shift of quasi-BIC resonance is small (less than 20 nm) in these studies, , due to the little variation in the refraction index of semiconductor and polymer.…”