arXiv subjects

Michael Kelzenberg

Publications and source records attributed to Michael Kelzenberg.

4 recordsLinked to original sources

arXiv2026

Electro-optic modulation of coherent and incoherent mid-IR radiation in two-dimensional arrays

Light in the mid-infrared (mid-IR) spans wavelengths from 3-8 $μ$m and is important to many applications such as gas sensing and thermal imaging. Due to materials challenges, there is currently a lack of mid-IR reconfigurable optical elements. Here, we present an electrically addressable metasurface for modulation of coherent and incoherent mid-IR radiation in two spatial dimensions. Our device achieves optical modulation due to the field-effect free-carrier depletion in a lightly doped ($10^{19}$ cm$^{-3}$) film of indium-tin-oxide (ITO) coupled to a gap plasmon resonator. By addressing 32 individual elements across the metasurface, we first demonstrate tunable diffraction of coherently reflected mid-IR light. Next, we introduce a scalable perimeter-addressed driving scheme for tunable diffraction in two dimensions. Finally, we demonstrate modulated emissivity with spatially reconfigurable two-dimensional patterns at elevated temperatures. This work advances the development of solid-state reflective beam-steering devices in the mid-IR and manipulation of thermally emitted incoherent radiation.

physics.optics↗

arXiv2025

Experimental demonstration of corrugated nanolaminate films as reflective light sails

Achieving laser-driven, reflective, relativistic light sails would represent a tremendous breakthrough for humankind, allowing us to advance our understanding of the solar system and deep space far beyond what we know from space probes, telescopes, and objects passing near Earth. Numerous sail film designs have been proposed, but none have been demonstrated that satisfy all of the stringent optical, mechanical, and mass budget constraints. Here we overcome this challenge by experimentally demonstrating a novel class of optically-optimized nanolaminate sails with strong and flexible hexagonally-corrugated microstructures. Our prototypes, fabricated from alumina and molybdenum disulfide using scalable semiconductor processing techniques, feature ultra-low areal densities of <1 g/m^2 and achieve experimentally-measured reflectivities of >50% and absorptivities of <4% within the Doppler-shifted laser wavelength range corresponding to accelerating to a fifth the speed of light. Moreover, we analyze reflectivity, strength, and mass constraints to show that our sails have the potential to achieve greater maximum velocities than other sail designs in the literature. Broadly, our films mark a significant leap forward toward plausible relativistic interstellar propulsion for intragalactic exploration

physics.optics↗

arXiv2022

A Lightweight Space-based Solar Power Generation and Transmission Satellite

We propose a novel design for a lightweight, high-performance space-based solar power array combined with power beaming capability for operation in geosynchronous orbit and transmission of power to Earth. We use a modular configuration of small, repeatable unit cells, called tiles, that each individually perform power collection, conversion, and transmission. Sunlight is collected via lightweight parabolic concentrators and converted to DC electric power with high efficiency III-V photovoltaics. Several CMOS integrated circuits within each tile generates and controls the phase of multiple independently-controlled microwave sources using the DC power. These sources are coupled to multiple radiating antennas which act as elements of a large phased array to beam the RF power to Earth. The power is sent to Earth at a frequency chosen in the range of 1-10 GHz and collected with ground-based rectennas at a local intensity no larger than ambient sunlight. We achieve significantly reduced mass compared to previous designs by taking advantage of solar concentration, current CMOS integrated circuit technology, and ultralight structural elements. Of note, the resulting satellite has no movable parts once it is fully deployed and all beam steering is done electronically. Our design is safe, scalable, and able to be deployed and tested with progressively larger configurations starting with a single unit cell that could fit on a cube satellite. The design reported on here has an areal mass density of 160 g/m2 and an end-to-end efficiency of 7-14%. We believe this is a significant step forward to the realization of space-based solar power, a concept once of science fiction.

astro-ph.IM↗

arXiv2019

A new metal transfer process for van der Waals contacts to vertical Schottky-junction transition metal dichalcogenide photovoltaics

Two-dimensional transition metal dichalcogenides are promising candidates for ultrathin optoelectronic devices due to their high absorption coefficients and intrinsically passivated surfaces. To maintain these near-perfect surfaces, recent research has focused on fabricating contacts that limit Fermi-level pinning at the metal-semiconductor interface. Here, we develop a new, simple procedure for transferring metal contacts that does not require aligned lithography. Using this technique, we fabricate vertical Schottky-junction $WS_2$ solar cells with Ag and Au as asymmetric work function contacts. Under laser illumination, we observe rectifying behavior and open-circuit voltage above 500 mV in devices with transferred contacts, in contrast to resistive behavior and open-circuit voltage below 15 mV in devices with evaporated contacts. One-sun measurements and device simulation results indicate that this metal transfer process could enable high-specific-power vertical Schottky-junction transition metal dichalcogenide photovoltaics, and we anticipate that this technique will lead to advances for two-dimensional devices more broadly.

physics.app-ph↗