Anti-Hermitian photodetector facilitating efficient subwavelength photon sorting

Abstract

The ability to split an incident light beam into separate wavelength bands is central to a diverse set of optical applications, including imaging, biosensing, communication, photocatalysis, and photovoltaics. Entirely new opportunities are currently emerging with the recently demonstrated possibility to spectrally split light at a subwavelength scale with optical antennas. Unfortunately, such small structures offer limited spectral control and are hard to exploit in optoelectronic devices. Here, we overcome both challenges and demonstrate how within a single-layer metafilm one can laterally sort photons of different wavelengths below the free-space diffraction limit and extract a useful photocurrent. This chipscale demonstration of anti-Hermitian coupling between resonant photodetector elements also facilitates near-unity photon-sorting efficiencies, near-unity absorption, and a narrow spectral response (∼ 30 nm) for the different wavelength channels. This work opens up entirely new design paradigms for image sensors and energy harvesting systems in which the active elements both sort and detect photons.

Spectral, spatial and polarization-selective perfect absorbers with large magnetic response for sensing and thermal emission control

“…As each nanoslit is independent of each other, one can create multi-band absorbers as far as each nanoslit is capable of absorbing all the incident light in one period. Thus, the structure can find applications in spatial and spectral light separation [47]. Our simulation shows that two spectra that are separated by more than 1μm in wavelength can also be sorted by designing the structure appropriately.…”

“…Previously [47], a bi-grating structure was proposed to achieve spectrally-selective absorption of incident light at two different wavelengths in each of the two slits. By using TM 1 guided mode and far-field coupling of the scattered fields from the two slits, the large absorption and thus the near-unity light sorting efficiency were reported.…”

Near-field resonant photon sorting applied: dual-band metasurface quantum well infrared photodetectors for gas sensing

“…Because each deep subwavelength cavity has an absorption cross section much larger than its geometrical area [13][14][15][16][17], each cavity realizes nearly perfect absorption of light at its resonance wavelength, without significant interference from its counterpart. Sorting efficiencies, the fraction of the absorption in the resonant cavity over the total absorption in the two cavities, as high as 95% have been observed [9,12,18].…”

Subwavelength pixelated CMOS color sensors based on anti-Hermitian metasurface

“…Anti-Hermitian (AH) systems have recently gained increasing attention due to their unique ability to increase the selectivity of resonant devices 4,5 , which are uniquely positioned to address both optical and electrical crosstalk, enabling pixels with subwavelength dimensions, promising for future optoelectronic systems. At the AH-coupling condition, the absorption profiles become sharpened to the extent that the overlap in absorption spectra, also known as crosstalk, becomes negligible 4 .…”

“…Till now, AH systems were mostly studied in the fields of quantum optics and nuclear physics, with other crosstalk mitigation schemes proposed for all-dielectric systems [6][7][8] . Anti-Hermitian coupling has been recently employed in micro-and nanophotonics with potential technological applications in photovoltaics, imaging, and display systems 4,5,[9][10][11][12] . However, current state-of-the-art AH systems have been restricted to a single spatial dimension, limited color channels, and lacked electrical integration with complementary metal-oxide-semiconductor (CMOS) compatible materials, which has hindered their adoption in practical settings.…”