Tunable Duplex Metalens Based on Phase-Change Materials in Communication Range

Abstract

Metalenses recently have attracted attention because of their more compact size in comparison with conventional lenses; they can also achieve better optical performance with higher resolution. Duplexer is an interesting function of a metalens that can distinguish different sources and divide them into two parts for specific purposes. In this article, we design tunable duplex metalenses with phase-change material Ge2Sb2Te5 for the first time. Two types of special unit cells are designed to modulate the incident lights, and four metalenses are designed based on the two types of unit cells. Specific phase profiles are calculated for different sections of metalens in which the corresponding unit cells are settled; accordingly, the metalenses can focus the incident lights at any positions according to our design. Moreover, the metalenses become selectable via tuning the state of phase-change material, which means that the output light field can be actively controlled. The proposal of our tunable duplex metalenses will offer new opportunities for active three-dimensional imaging or optical coding.

Actively Tunable Metalens Array Based on Patterned Phase Change Materials

“…Compared with conventional lens, metalens possess a smaller size due to a meta-unit induced abrupt phase shift for its phase distribution. Recently, many researchers have been dedicated to improving the optical performance of metalens, for example, focusing several discrete wavelengths at the same position [15,16]; achromatic focusing at a continuous broadband [17,18]; multi-focus for different wavelengths or polarized light [19,20]; and tunable ability utilizing stretchable materials, liquid metal, or phase change materials [20][21][22][23]. All of these contributions have explored an exciting field to replace conventional lens with metalens to obtain better optical performance and higher integration.…”

“…When the GST is tuned between two states, the corresponding permittivity will be changed simultaneously, which can be used to realize active control. Due to its remarkable tuning abilities such as high stability and fast switch speed [29,30], GST has been applied in many novel tunable nano-photonic devices such as multi-wavelength duplex metalens, dipole-quadrupole (DQ) Fano resonance (FR) induced lateral force, beam steering, filter, color control, and ultraviolet/high-energy-visible resonances by combining with metasurfaces [20,[31][32][33][34][35][36], which has proved to be the great potential of GST. Nevertheless, the research for tunable metalens array using phase change materials has not been explored yet.…”

High-Efficiency, Broadband, Near Diffraction-Limited, Dielectric Metalens in Ultraviolet Spectrum

“…Metasurfaces have stirred up a spree of research interest in recent years due to their brilliant performance in the field of electromagnetic wave manipulation [1][2][3][4][5][6][7][8][9]. Metasurfaces are based on some well-designed subwavelength scale arrays of resonators to manipulate the amplitude, phase, propagation direction, and polarization of light to nanoscale resolution at an ease [10][11][12][13][14][15][16][17][18][19], making them an appropriate option for miniaturization and integration of photonic systems.…”

Polarization Insensitive, Broadband, Near Diffraction-Limited Metalens in Ultraviolet Region

“…On the other hand, metasurfaces that are ultra-thin optical structures have appeared to provide a substantial way, by discrete phase changes over the subwavelength scale, to control the amplitude, phase and polarization of the light [2][3][4] to realize optical functionalities by their planar structure [5] such as meta-holograms [6], axicons metalenses [7], antireflection coatings color filters [8], color imaging [9,10], optical vortex generators and polarizers [11,12] and numerous novel photonic devices and systems [13]. Metasurfaces have gained substantial interest in the past few years [14,15] in having the ability to replace the bulky, expensive, low-efficiency optical components [7,16] and provide a gateway towards the miniaturization of the optical devices and components [17,18]. Moreover, metasurfaces are greatly desired in integrated optics and electronic circuits, portals, and mobile devices.…”