Abstract
Phased-array metasurfaces have been extensively used for wavefront shaping of coherent incident light. Due to the incoherent nature of spontaneous emission, the ability to similarly tailor photoluminescence remains largely unexplored. Recently, unidirectional photoluminescence from InGaN/GaN quantum-well metasurfaces incorporating one-dimensional phase profiles has been shown. However, the possibility of generating arbitrary two-dimensional waveforms—such as focused beams—is not yet realized. Here, we demonstrate two-dimensional metasurface axicons and lenses that emit collimated and focused beams, respectively. First, we develop off-axis meta-axicon/metalens equations designed to redirect surface-guided waves that dominate the natural emission pattern of quantum wells. Next, we show that photoluminescence properties are well predicted by passive transmission results using suitably engineered incident light sources. Finally, we compare collimating and focusing performances across a variety of different light-emitting metasurface axicons and lenses. These generated two-dimensional phased-array photoluminescence waveforms facilitate future development of light sources with arbitrary functionalities.
Highlights
Phased-array metasurfaces have been extensively used for wavefront shaping of coherent incident light
We show how spontaneous emission properties can be predicted via transmission measurements with engineered incident light sources
We demonstrate that metalenses focus the emitted PL at the designed focal lengths with beam widths that are inversely proportional to the numerical aperture
Summary
Phased-array metasurfaces have been extensively used for wavefront shaping of coherent incident light. We compare collimating and focusing performances across a variety of different light-emitting metasurface axicons and lenses These generated two-dimensional phased-array photoluminescence waveforms facilitate future development of light sources with arbitrary functionalities. Subsequent studies of luminescent metasurfaces have mostly comprised uniform arrays that modify and enhance spectra and directivity using resonant nanoantenna structures that are subwavelength in all dimensions[23,24,25,26,27,28] These demonstrations lack the 2π phase range, amplitude control, and spatially extended phasing needed to achieve the robust wavefront control typical of passive metasurfaces. We demonstrate that metalenses focus the emitted PL at the designed focal lengths with beam widths that are inversely proportional to the numerical aperture These results pave the way for new light sources where photons can be generated and redirected within the same compact space
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