arXiv subjects

Arka Majumdar

Publications and source records attributed to Arka Majumdar.

At least 37 records · Page 2Linked to original sources

arXiv2025

Deterministic Printing of Single Quantum Dots

The unique optical properties of quantum dots (QDs), size-tunable emission and high quantum yield, make them ideal candidates for applications in secure quantum communication, quantum computing, targeted single-cell and molecular tagging, and sensing. Scalable and deterministic heterointegration strategies for single QDs have, however, remained largely out of reach due to inherent material incompatibilities with conventional semiconductor manufacturing processes. To advance scalable photonic quantum device architectures, it is therefore crucial to adopt placement and heterointegration strategies that can address these challenges. Here, we present an electrohydrodynamic (EHD) printing model, single particle extraction electrodynamics (SPEED) printing, that exploits a novel regime of nanoscale dielectrophoretics to print and deterministically position single colloidal QDs. Using QDs solubilized in apolar solvents, this additive, zero-waste nanomanufacturing process overcomes continuum fluid surface energetics and stochastic imprecision that limited previous colloidal deposition strategies, achieving selective extraction and deposition of individual QDs at sub-zeptoliter volumes. Photoluminescence and autocorrelation function (g(2)) measurements confirm nanophotonic cavity-QD integration and single-photon emission from single printed QDs. By enabling deterministic placement of single quantum dots, this method provides a powerful, scalable, and sustainable platform for integrating complex photonic circuits and quantum light sources with nanoscale precision.

physics.optics↗

arXiv2025

Electrically reconfigurable nonvolatile transmissive metasurface in visible

The synergy between metasurfaces and non-volatile phase change materials (PCMs) has created many reconfigurable photonic devices for applications in optical memory, optical computing and optical communications. But these advances have been limited to the infrared wavelengths due to the high loss of PCMs in the visible regime. Here we demonstrate a nonvolatile visible metasurface that is electrically reconfigurable using wide bandgap PCM Sb2S3. Our device supports a resonant mode at 610 nm, a wavelength largely under-explored for PCM-based metasurfaces. By incorporating only a 20 nm thick layer of Sb2S3, we experimentally demonstrate a resonance tuning range of 16 nm. Reversible switching of the metasurface is accomplished in situ using a carefully engineered, ultrathin doped silicon micro-heater. Our work paves the way for integrating PCMs into visible-frequency systems, particularly for human-centric applications such as augmented and virtual reality displays.

physics.optics↗

arXiv2025

Neural Tangent Knowledge Distillation for Optical Convolutional Networks

Hybrid Optical Neural Networks (ONNs, typically consisting of an optical frontend and a digital backend) offer an energy-efficient alternative to fully digital deep networks for real-time, power-constrained systems. However, their adoption is limited by two main challenges: the accuracy gap compared to large-scale networks during training, and discrepancies between simulated and fabricated systems that further degrade accuracy. While previous work has proposed end-to-end optimizations for specific datasets (e.g., MNIST) and optical systems, these approaches typically lack generalization across tasks and hardware designs. To address these limitations, we propose a task-agnostic and hardware-agnostic pipeline that supports image classification and segmentation across diverse optical systems. To assist optical system design before training, we estimate achievable model accuracy based on user-specified constraints such as physical size and the dataset. For training, we introduce Neural Tangent Knowledge Distillation (NTKD), which aligns optical models with electronic teacher networks, thereby narrowing the accuracy gap. After fabrication, NTKD also guides fine-tuning of the digital backend to compensate for implementation errors. Experiments on multiple datasets (e.g., MNIST, CIFAR, Carvana Masking) and hardware configurations show that our pipeline consistently improves ONN performance and enables practical deployment in both pre-fabrication simulations and physical implementations.

cs.CV↗

arXiv2025

Mixed Precision Photonic Computing with 3D Electronic-Photonic Integrated Circuits

We propose advancing photonic in-memory computing through three-dimensional photonic-electronic integrated circuits using phase-change materials (PCM) and AlGaAs-CMOS technology. These circuits offer high precision (greater than 12 bits), scalability (greater than 1024 by 1024), and massive parallelism (greater than 1 million operations) across the wavelength, spatial, and temporal domains at ultra-low power (less than 1 watt per PetaOPS). Monolithically integrated hybrid PCM-AlGaAs memory resonators handle coarse-precision iterations (greater than 5-bit most significant bit precision) through reversible PCM phase transitions. Electro-optic memristive tuning enables fine-precision updates (greater than 8-bit least significant bit precision), resulting in over 12-bit precision for in-memory computing. The use of low-loss PCM (less than 0.01 dB per cm) and electro-optical tuning yields memristive optical resonators with high Q-factors (greater than 1 million), low insertion loss, and low tuning power. A W by W photonic tensor core composed of PCM-AlGaAs memresonators performs general matrix multiplication (GEMM) across W wavelengths from optical frequency combs, with minimal crosstalk and loss. Hierarchical scaling in the wavelength domain (K) and spatial domain (L) enables this system to address high-dimensional (N) scientific partial differential equation (PDE) problems in a single constant-time operation, compared to the conventional quadratic-time (N squared) computational complexity.

physics.optics↗

arXiv2025

Scalable Ion Fluorescence Collection Using a Trap-Integrated Metalens

A scaled trapped-ion quantum computer will require efficient fluorescence collection across a large area. Here we propose and demonstrate a compact monolithically integrated system featuring a metalens fabricated on the backside of a surface ion trap. A 40$\times$100 $μ$m aperture enables a simulated point-source collection efficiency of 0.91% and a measured point-source detection efficiency of 0.58%. Increasing the aperture area to 40$\times$600 $μ$m boosts the simulated collection efficiency to 3.17%$-$comparable to that of a conventional objective with a numerical aperture of 0.35. Further improvements are possible by co-optimizing the electrode and aperture geometry. An undercut of the electrode substrate at the aperture ensures a large distance between the ion and dielectric substrate without compromising collection efficiency. The metalens directly collimates the collected fluorescence, eliminating the need for a high numerical aperture objective. An array of such readout zones will offer a compact, scalable solution for high-fidelity parallel readout in next-generation trapped-ion quantum processors.

quant-ph↗

arXiv2025

Compact broadband thermal absorbers based on plasmonic fractal metasurfaces

The ability to efficiently absorb thermal radiation within a small material volume is crucial for the realization of compact and high spatial resolution thermal imagers. Here we propose and experimentally demonstrate a compact plasmonic metasurface for broadband absorption in the 6 to 14 microns wavelength range. As opposed to previous works, our metasurface leverages strongly localized electromagnetic modes to achieve high absorption within a compact form factor. We numerically investigate the spectral response of finite arrays of fractals and show that the absorption enhancement provided by arrays with greater than 6x6 fractals covering a total area of only 30x30 microns squared is similar to that of an infinitely periodic array. Furthermore, we experimentally validate our metasurface's absorption enhancement and demonstrate a good qualitative agreement between the measured and simulated spectral responses. Owing to its ability to achieve broadband absorption enhancement in a compact footprint, our metasurface provides new avenues for the realization of next generation infrared sensors and bolometers.

physics.optics↗

arXiv2025

NEO-PGA: Nonvolatile electro-optically programmable gate array

Programmable photonic integrated circuits (PICs) offer a unique opportunity to create a flexible platform, akin to electronic field programmable gate array (FPGA). These photonic PGAs can implement versatile functionalities for applications ranging from optical interconnects to microwave photonics. However, state-of-the-art programmable photonics relies predominantly on volatile thermo-optic tuning, which suffers from high static power consumption, large footprints, and thermal crosstalk. All these dramatically limit the gate density and pose a fundamental limit to the scalability. Chalcogenide-based phase-change materials (PCMs) offer a superior alternative due to their nonvolatility and substantial optical contrast, though challenges such as optical loss, and bit precision severely limited their application in large-scale PICs. Here, we demonstrate precise, multi-bit, low-loss tuning of the emerging PCM Sb2Se3 using a closed-loop, "program-and-verify" method. Electrically reconfigurable PCM-integrated silicon photonic gates are implemented on a 300mm silicon photonic platform, using circulating and forward Mach-Zehnder interferometer (MZI) meshes. In the circulating mesh, we realize broadband optical switching fabrics and high-Q coupled resonators with unprecedented local control of coupling rates, which further enable exploration of coupled-cavity systems. The forward mesh supports self-configurable MZIs that sort two orthogonal beams to different ports. These results showcase a new type of scalable photonic PGA enabled by PCMs, offering a pathway toward general-purpose, on-chip programmable photonic systems.

physics.optics↗

arXiv2025

Near-visible low power tuning of nematic-liquid crystal integrated silicon nitride ring resonator

The development of compact, low-power, and high-performance integrated photonic phase shifters is critical for advancing emerging technologies such as light detection and ranging (LiDAR), optical information processing and quantum applications. Liquid crystal (LC)-based phase shifters offer a promising solution thanks to their large refractive index contrast and their low power consumption. However, it remains challenging to incorporate LCs into integrated photonics and the operating wavelength has been limited to near infrared. Here, we demonstrate a liquid-crystal-based phase shifter operating at 780 nm, a relevant wavelength for cold atom-based quantum applications, by incorporating nematic LCs (E7) into a silicon nitride (SiN) ring resonator. Our device achieves 2pi phase modulation with very low power of 2.1 nW and low driving voltages of 7 V with exceptionally low Vpi times L (half wave voltage times length) value of 0.014 V-cm, enabling precise control over light propagation in a compact footprint. This work marks a significant step toward realizing low-power, compact, and efficient LC integrated photonic circuits based on SiN platform for next-generation LiDAR and quantum optical systems.

physics.optics↗

arXiv2025

Electrically reconfigurable nonvolatile flatband absorbers in the mid-infrared with wide spectral tuning range

While recent advances in reconfigurable photonics have provided new avenues for manipulating light on the subwavelength scale, on-demand control of infrared absorption remains elusive. Here, we experimentally demonstrate a plasmonic metasurface based on the phase change material Ge2Sb2Te5 with in-situ electrically-switchable infrared absorption in the 3-5 microns wavelength range. Unlike traditional infrared microstructures based on volatile phase change materials, our device does not require the external stimuli to be continuously applied in order to maintain a given optical state, thus enabling zero static power operation. Furthermore, the 400x deep-subwavelength field localization supported by our device not only allows robust tuning of its spectral response but also makes its absorptivity independent of the angle of incidence, thus enabling a flatband behavior. We conduct switching of our device using rapid thermal annealing and reversible switching using electrical pulses over 26 cycles. Our device provides new avenues for infrared absorption control and serves as a steppingstone for the next generation of mid-wave infrared photonics.

physics.optics↗

arXiv2025

Collaborative On-Sensor Array Cameras

Modern nanofabrication techniques have enabled us to manipulate the wavefront of light with sub-wavelength-scale structures, offering the potential to replace bulky refractive surfaces in conventional optics with ultrathin metasurfaces. In theory, arrays of nanoposts provide unprecedented control over manipulating the wavefront in terms of phase, polarization, and amplitude at the nanometer resolution. A line of recent work successfully investigates flat computational cameras that replace compound lenses with a single metalens or an array of metasurfaces a few millimeters from the sensor. However, due to the inherent wavelength dependence of metalenses, in practice, these cameras do not match their refractive counterparts in image quality for broadband imaging, and may even suffer from hallucinations when relying on generative reconstruction methods. In this work, we investigate a collaborative array of metasurface elements that are jointly learned to perform broadband imaging. To this end, we learn a nanophotonics array with 100-million nanoposts that is end-to-end jointly optimized over the full visible spectrum--a design task that existing inverse design methods or learning approaches cannot support due to memory and compute limitations. We introduce a distributed meta-optics learning method to tackle this challenge. This allows us to optimize a large parameter array along with a learned meta-atom proxy and a non-generative reconstruction method that is parallax-aware and noise-aware. The proposed camera performs favorably in simulation and in all experimental tests irrespective of the scene illumination spectrum.

physics.optics↗

arXiv2025

Free Space Few-Photon Nonlinearity in Critically Coupled Polaritonic Metasurfaces

Few-photon optical nonlinearity in planar solid-state systems is challenging yet crucial for quantum and classical optical information processing. Polaritonic nonlinear metasurfaces have emerged as a promising candidate to push the photon number down -- but have often been hindered by challenges like the poor photon-trapping efficiency and lack of modal overlap. Here, we address these issues in a self-hybridized perovskite metasurface through critical coupling engineering, and report strong polaritonic nonlinear absorption at an ultra-low incident power density of only 519 W/cm2 (2 orders of magnitude lower than the state of art in free-space planar devices), with an estimated photon number of 6.12 per cavity lifetime. Taking advantage of a quasi-bound-state-in-the-continuum design with asymmetry-controlled quality-(Q)-factor, we systematically examine the Q-dependent device nonlinearity and determine the optimal cavity critical coupling condition. With the optimized device, we demonstrate at 6 Kelvin a tunable nonlinear response from reverse saturable absorption to saturable absorption at varying pump powers, with a maximal effective nonlinear absorption coefficient up to 29.4+-5.8 cm/W (6 orders of magnitude larger than unpatterned perovskites) at 560 nm wavelength. In addition, the cavity-exciton detuning dependent device response is analyzed and well explained by a phase-space-filling model, elucidating the underlying physics and the origin of giant nonlinearity. Our study paves the way towards practical flat nonlinear optical devices with large functional areas and massive parallel operation capabilities.

physics.optics↗

arXiv2025

Nanocavity-Enhanced Second-Harmonic Generation from Colossal Quantum Dots

Colloidal quantum dots (QDs) are an attractive medium for nonlinear optics and deterministic heterogeneous integration with photonic devices. Their intrinsic nonlinearities can be strengthened further by coupling QDs to low mode-volume photonic nanocavities, enabling low-power, on-chip nonlinear optics. In this paper, we demonstrated cavity-enhanced second harmonic generation via integration of colossal QDs with a silicon nitride nanobeam cavity. By pumping the cavity-QD system with an ultrafast pulsed laser, we observed a strong second harmonic generation from the cavity-coupled QD, and we estimate an enhancement factor of ~3,040. Our work, coupled with previously reported deterministic positioning of colossal QDs, can enable a scalable QD-cavity platform for low-power nonlinear optics.

physics.optics↗

arXiv2025

Singleshot Multispectral Imaging via a Chromatic Metalens Array

Real time, singleshot multispectral imaging systems are crucial for environment monitoring and biomedical imaging. Most singleshot multispectral imagers rely on complex computational backends, which precludes real time operations. In this work, we leverage the spectral selectivity afforded by engineered photonic materials to perform bulk of the multispectral data extraction in the optical domain, thereby circumventing the need for heavy backend computation. We use our imager to extract multispectral data for two real world objects at 8 predefined spectral channels in the 400 to 900 nm wavelength range. For both objects, an RGB image constructed using extracted multispectral data shows good agreement with an image taken using a phone camera, thereby validating our imaging approach. We believe that the proposed system can provide new avenues for the development of highly compact and low latency multispectral imaging technologies.

physics.optics↗

arXiv2025

Heteroepitaxial growth of highly anisotropic $Sb_{2}Se_{3}$ films on GaAs

The epitaxial integration of anisotropic materials with mainstream cubic semiconductors opens new routes to advanced electronic and photonic devices with directional properties. In this work, we synthesize heteroepitaxial thin films of orthorhombic "quasi-1D" $Sb_{2}Se_{3}$ on cubic GaAs(001) using molecular beam epitaxy. Traditionally, the synthesis of anisotropic films with low symmetry materials is challenging due to multiple grain orientations that form. On a macroscopic scale, such a film tends towards isotropic properties, even if individual grains possess anisotropic responses. We achieve epitaxial $Sb_{2}Se_{3}$ grains on pristine homoepitaxial GaAs templates at low temperatures of 180-200 °C. With the $Sb_{2}Se_{3}$ 1D axis aligned in-plane to GaAs [110] and the primary van der Waals direction lying out-of-plane, we find a birefringence of 0.2 between in-plane orthogonal directions and a giant out-of-plane birefringence greater than 1 at telecom wavelengths. Growth at higher temperatures up to 265 °C yields $Sb_{2}Se_{3}$ of an unusual in-plane rotated texture that further enhances the in-plane optical index anisotropy to 0.3.

cond-mat.mtrl-sci↗

arXiv2025

End-to-end metasurface design for temperature imaging via broadband Planck-radiation regression

We present a theoretical framework for temperature imaging from long-wavelength infrared thermal radiation (e.g. 8-12 $μ$m) through the end-to-end design of a metasurface-optics frontend and a computational-reconstruction backend. We introduce a new nonlinear reconstruction algorithm, ``Planck regression," that reconstructs the temperature map from a grayscale sensor image, even in the presence of severe chromatic aberration, by exploiting blackbody and optical physics particular to thermal imaging. We combine this algorithm with an end-to-end approach that optimizes a manufacturable, single-layer metasurface to yield the most accurate reconstruction. Our designs demonstrate high-quality, noise-robust reconstructions of arbitrary temperature maps (including completely random images) in simulations of an ultra-compact thermal-imaging device. We also show that Planck regression is much more generalizable to arbitrary images than a straightforward neural-network reconstruction, which requires a large training set of domain-specific images.

physics.optics↗

arXiv2024

Computational metaoptics for imaging

Metasurfaces -- ultrathin structures composed of subwavelength optical elements -- have revolutionized light manipulation by enabling precise control over electromagnetic waves' amplitude, phase, polarization, and spectral properties. Concurrently, computational imaging leverages algorithms to reconstruct images from optically processed signals, overcoming limitations of traditional imaging systems. This review explores the synergistic integration of metaoptics and computational imaging, "computational metaoptics," which combines the physical wavefront shaping ability of metasurfaces with advanced computational algorithms to enhance imaging performance beyond conventional limits. We discuss how computational metaoptics addresses the inherent limitations of single-layer metasurfaces in achieving multifunctionality without compromising efficiency. By treating metasurfaces as physical preconditioners and co-designing them with reconstruction algorithms through end-to-end (inverse) design, it is possible to jointly optimize the optical hardware and computational software. This holistic approach allows for the automatic discovery of optimal metasurface designs and reconstruction methods that significantly improve imaging capabilities. Advanced applications enabled by computational metaoptics are highlighted, including phase imaging and quantum state measurement, which benefit from the metasurfaces' ability to manipulate complex light fields and the computational algorithms' capacity to reconstruct high-dimensional information. We also examine performance evaluation challenges, emphasizing the need for new metrics that account for the combined optical and computational nature of these systems. Finally, we identify new frontiers in computational metaoptics which point toward a future where computational metaoptics may play a central role in advancing imaging science and technology.

physics.optics↗

arXiv2024

Computed tomography using meta-optics

Computer vision tasks require processing large amounts of data to perform image classification, segmentation, and feature extraction. Optical preprocessors can potentially reduce the number of floating point operations required by computer vision tasks, enabling low-power and low-latency operation. However, existing optical preprocessors are mostly learned and hence strongly depend on the training data, and thus lack universal applicability. In this paper, we present a metaoptic imager, which implements the Radon transform obviating the need for training the optics. High quality image reconstruction with a large compression ratio of 0.6% is presented through the use of the Simultaneous Algebraic Reconstruction Technique. Image classification with 90% accuracy is presented on an experimentally measured Radon dataset through neural network trained on digitally transformed images.

cs.CV↗

arXiv2024

Opportunities and Challenges of Solid-State Quantum Nonlinear Optics

Nonlinear interactions between single quantum particles are at the heart of any quantum information system, including analog quantum simulation and fault-tolerant quantum computing. This remains a particularly difficult problem for photonic qubits, as photons do not interact with each other. While engineering light-matter interaction can effectively create photon-photon interaction, the required photon number to observe any nonlinearity is very high, where any quantum mechanical signature disappears. However, with emerging low-dimensional materials, and engineered photonic resonators, the photon number can be potentially reduced to reach the quantum nonlinear optical regime. In this review paper, we discuss different mechanisms exploited in solid-state platforms to attain quantum nonlinear optics. We review emerging materials and optical resonator architecture with different dimensionalities. We also present new research directions and open problems in this field.

physics.optics↗