arXiv subjects

Ali Najjar Amiri

Publications and source records attributed to Ali Najjar Amiri.

5 recordsLinked to original sources

arXiv2026

Collective Radiative Enhancement of Rare-Earth Ions in Lithium Niobate via Engineered LargeArea Nanohole Arrays

Conventional approaches to light-matter interactions rely on engineering photonic density of states. More recently, tailoring the spatial geometry of atoms or emitters themselves has emerged as a powerful and complementary route to control collective radiative properties. Here we experimentally realize a geometry-engineered ensemble of rare-earth ions by fabricating a periodic array of subwavelength gold nanoholes on lithium niobate implanted with thulium ions, forming a semi-two-dimensional array of quantum emitters embedded in a high-index crystalline thin film. The hybrid structure can simultaneously support localized and lattice plasmon resonances from the metallic array and collective atomic resonances from the ion ensemble. Using time-resolved photoluminescence and temperature-dependent measurements, we observe enhanced radiative emission attributed to collective atomic effects mediated by the nanohole lattice, distinct from single-emitter Purcell enhancement. Our results demonstrate a new regime of light-matter interaction opening a pathway toward broadband and scalable, geometry-controlled quantum optical interfaces in solid-state platforms.

physics.optics↗

arXiv2025

Universal on-chip polarization handling with deep photonic networks

We propose a novel design paradigm for arbitrarily capable deep photonic networks of cascaded Mach-Zehnder Interferometers (MZIs) for on-chip universal polarization handling. Using a device architecture made of cascaded Mach-Zehnder interferometers, we modify and train the phase difference between interferometer arms for both polarizations through wide operation bandwidths. Three proof-of-concept polarization handling devices are illustrated using a software-defined, physics-informed neural framework, to achieve user-specified target device responses as functions of polarization and wavelength. These devices include a polarization splitter, a polarization-independent power splitter, and an arbitrary polarization-dependent splitter to illustrate the capabilities of the design framework. The performance for all three devices is optimized using transfer matrix calculations; and their final responses are verified through 3D-FDTD simulations. All devices demonstrate state-of-the-art performance metrics with over 20 dB extinction, and flat-top transmission bands through bandwidths of 120 nm. In addition to the functional diversity enabled, the optimization for each device is completed in under a minute, highlighting the computational efficiency of the design paradigm presented. These results demonstrate the versatility of the deep photonic network design ecosystem in polarization management, unveiling promising prospects for advanced on-chip applications in optical communications, sensing, and computing.

physics.optics↗

arXiv2025

On-chip arbitrary dispersion engineering with deep photonic networks

We demonstrate the design and optimization of on-chip arbitrary dispersion profiles using deep photonic networks constructed from custom-designed Mach-Zehnder interferometers. These photonic networks employ optimizable waveguide tapers, enabling precise engineering of wavelength-dependent dispersion profiles. We experimentally demonstrate a proof-of-concept two-port photonic network that exhibits a highly nonintuitive triangular dispersion profile over the wavelength range of 1.54 $μ\mathrm{m}$ to 1.58 $μ\mathrm{m}$ while simultaneously achieving a flat-band transmission with an insertion loss of less than 0.7 dB. We also illustrate the potential of multi-port photonic networks to enhance design freedom for more complex and customizable dispersion profiles, enabling new possibilities for on-chip dispersion engineering.

physics.optics↗

arXiv2024

Enhanced Imaging of Electronic Hot Spots Using Quantum Squeezed Light

Detecting electronic hot spots is important for understanding the heat dissipation and thermal management of electronic and semiconductor devices. Optical thermoreflective imaging is being used to perform precise temporal and spatial imaging of heat on wires and semiconductor materials. We apply quantum squeezed light to perform thermoreflective imaging on micro-wires, surpassing the shot-noise limit of classical approaches. We obtain a far-field temperature sensing accuracy of 42 mK after 50 ms of averaging and show that a $256\times256$ pixel image can be constructed with such sensitivity in 10 minutes. We can further obtain single-shot temperature sensing of 1.6 K after only 10 $\mathrm{μs}$ of averaging enabling dynamical study of heat dissipation. Not only do the quantum images provide accurate spatio-temporal information about heat distribution, but the measure of quantum correlation provides additional information, inaccessible by classical techniques, that can lead to a better understanding of the dynamics. We apply the technique to both Al and Nb microwires and discuss the applications of the technique in studying electron dynamics at low temperatures.

quant-ph↗

arXiv2023

Deep Photonic Networks with Arbitrary and Broadband Functionality

Growing application space in optical communications, computing, and sensing continues to drive the need for high-performance integrated photonic components. Designing these on-chip systems with complex and application-specific functionality requires beyond what is possible with physical intuition, for which machine learning-based design methods have recently become popular. However, as the expensive computational requirements for physically accurate device simulations last a critical challenge, these methods typically remain limited in scalability and the optical design degrees of freedom they can provide for application-specific and arbitrary photonic integrated circuits. Here, we introduce a highly-scalable, physics-informed framework for the design of on-chip optical systems with arbitrary functionality based on a deep photonic network of custom-designed Mach-Zehnder interferometers. Using this framework, we design ultra-broadband power splitters and a spectral duplexer, each in less than two minutes, and demonstrate state-of-the-art experimental performance with less than 0.66 dB insertion loss and over 120 nm of 1-dB bandwidth for all devices. Our presented framework provides an essential tool with a tractable path towards the systematic design of large-scale photonic systems with custom and broadband power, phase, and dispersion profiles for use in multi-band optical applications including high-throughput communications, quantum information processing, and medical/biological sensing.

cs.ET↗