arXiv subjects

Jack A. Smith

Publications and source records attributed to Jack A. Smith.

5 recordsLinked to original sources

arXiv2026

Chip-scale nanostructured chaotic billiards for broadband speckle spectrometry

Computational on-chip spectrometers are emerging as a powerful platform for portable spectral analysis, combining photonic integration with advanced signal processing to enable a wide range of in-situ sensing applications. We propose a broadband reconstructive spectrometer based on wave chaos in a stadium microresonator with a nanostructured scattering layer for full-area speckle readout. Wavelength dependent interference within the chaotic microresonator encodes the spectral information into a spatial intensity pattern that can be computationally inverted to reconstruct the input spectra. The optimal fabrication parameters of the SU-8 polymer nanostructured layer yield a surface roughness of 176nm and a root mean square thickness of ~2um. We experimentally validate our spectrometer at visible and infrared wavelengths, with resolutions of 43pm at 630nm and 8.2pm at 1550nm. The spectral reconstruction is demonstrated for single and multiple narrowline sources as well as for a broadband (~1nm) pulsed laser source. The broad experimental validation and compact footprint (0.05mm2) establishes our chaotic microresonator-based speckle spectrometer as a robust and versatile platform for high-resolution, on-chip spectral sensing.

physics.optics↗

arXiv2025

Robust Physical Encryption and Unclonable Object Identification in Classical Optical Networks using Standard Integrated Photonic Components

Spectral complexity is a useful resource in physical device identification, disorder-enhanced spectroscopy, and machine learning, but is often achieved in chip-scale devices at the expense of propagation loss, scalability, or reconfigurability. In this work, we demonstrate that device specific spectral complexity can be achieved using completely standardized photonic building blocks. Using a waveguide Mach-Zehnder interferometer internally loaded with two sets of non-concentric dual ring resonators, we demonstrate the generation of unclonable keys for one-time pad encryption which can be reconfigured on the fly by applying small voltages to on-chip thermo-optic elements. With this method, we access a keyspace larger than 12 Tb for a single device with simple, single-mode waveguide input and output coupling. Using two devices at either end of a communication channel, we show that an eavesdropper tapping the channel fibre link would be unable to recover the same spectrum measured at either end of the link, providing physical encryption for key distribution. Furthermore, being purely classical, this form of secure communications does not require quantum photonic sources or detectors, and can therefore be easily integrated into pre-existing telecommunication architectures.

physics.optics↗

arXiv2025

On-chip wave chaos for photonic extreme learning

The increase in demand for scalable and energy efficient artificial neural networks has put the focus on novel hardware solutions. Integrated photonics offers a compact, parallel and ultra-fast information processing platform, specially suited for extreme learning machine (ELM) architectures. Here we experimentally demonstrate a chip-scale photonic ELM based on wave chaos interference in a stadium microcavity. By encoding the input information in the wavelength of an external single-frequency tunable laser source, we leverage the high sensitivity to wavelength of injection in such photonic resonators. We fabricate the microcavity with direct laser writing of SU-8 polymer on glass. A scattering wall surrounding the stadium operates as readout layer, collecting the light associated with the cavity's leaky modes. We report uncorrelated and aperiodic behavior in the speckles of the scattering barrier from a high resolution scan of the input wavelength. Finally, we characterize the system's performance at classification in four qualitatively different benchmark tasks. As we can control the number of output nodes of our ELM by measuring different parts of the scattering barrier, we demonstrate the capability to optimize our photonic ELM's readout size to the performance required for each task.

physics.optics↗

arXiv2024

Transfer printing micro-assembly of silicon photonic crystal cavity arrays: beating the fabrication tolerance limit

Photonic crystal cavities (PhCCs) can confine optical fields in ultra-small volumes, enabling efficient light-matter interactions for quantum and non-linear optics, sensing and all-optical signal processing. The inherent nanometric tolerances of micro-fabrication platforms can induce cavity resonant wavelength shifts two-orders of magnitude larger than cavity linewidths, prohibiting fabrication of arrays of nominally identical devices. We address this device variability by fabricating PhCCs as releasable pixels that can be transferred from their native substrate to a receiver where ordered micro-assembly can overcome the inherent fabrication variance. We demonstrate the measurement, binning and transfer of 119 PhCCs in a single session, producing spatially ordered arrays of PhCCs, sorted by resonant wavelength. Furthermore, the rapid in-situ measurement of the devices enables measurements of the PhCCs dynamic response to the print process for the first time, showing plastic and elastic effects in the seconds to hours range.

physics.optics↗

arXiv2022

Photonic integration of lithium niobate micro-ring resonators onto silicon nitride waveguide chips by transfer-printing

The heterogeneous integration of lithium niobate photonic waveguide devices onto a silicon nitride waveguide platform via a transfer-printing approach has been demonstrated for the first time. A fabrication process was developed to make free-standing lithium niobate membrane devices compatible with back-end integration onto photonic integrated circuits. Micro-ring resonators in membrane format were lithographically defined by using laser direct writing and plasma dry etching. The lithium niobate micro-ring resonators were then transferred from their host substrate and released onto a silicon nitride waveguide chip. An all-pass ring resonator transmission spectrum was obtained in the 1.5 μm to 1.6 μm wavelength range, with a measured loaded Q-factor larger than 32000.

physics.optics↗