AbstractPhysical unclonable function (PUF) has emerged as a promising and important security primitive for use in modern systems and devices, due to their increasingly embedded, distributed, unsupervised, and physically exposed nature. However, optical PUFs based on speckle patterns, chaos, or ‘strong’ disorder are so far notoriously sensitive to probing and/or environmental variations. Here we report an optical PUF designed for robustness against fluctuations in optical angular/spatial alignment, polarization, and temperature. This is achieved using an integrated quasicrystal interferometer (QCI) which sensitively probes disorder while: (1) ensuring all modes are engineered to exhibit approximately the same confinement factor in the predominant thermo-optic medium (e. g. silicon), and (2) constraining the transverse spatial-mode and polarization degrees of freedom. This demonstration unveils a new means for amplifying and harnessing the effects of ‘weak’ disorder in photonics and is an important and enabling step toward new generations of optics-enabled hardware and information security devices.

We consider the problem of efficiently coupling light into a recently proposed all-dielectric subdiffraction waveguide exhibiting an ultra-small mode area (An ∼ 10−3 λ 0 2 ), more than one order of magnitude lower than a diffraction limited strip waveguide (An ∼ 10−2 λ 0 2 ). Two prospective coupling solutions are compared with respect to coupling efficiency, fabrication tolerance, and optical bandwidth. The strategy based on adiabatic mode evolution is shown to be superior with respect to fabrication tolerance as it preserves ≥99% efficiency under +/- 10 nm critical dimension (CD) variations, whereas the directional coupling approach achieves only ≥60% efficiency for the same CD errors. Similar results are obtained with respect to optical bandwidth, with the nominal adiabatic mode evolution and directional coupling based designs achieving >95% efficiency over wavelength ranges of >200 nm and ∼50 nm respectively. The superior performance of the adiabatic design requires a coupler length in the range L ≈ 100–250 µm. The results yield a high performance, compact, and straightforward design solution for efficiently interfacing between conventional diffraction limited waveguides and all-dielectric subdiffraction waveguides with an ultra-small mode area.

We demonstrate the uniqueness, unclonability and secure authentication of N = 56 physical unclonable functions (PUFs) realized from silicon photonic moiré quasicrystal interferometers. Compared to prior photonic-PUF demonstrations typically limited in scale to only a handful of unique devices and on the order of 10 false authentication attempts, this work examines > 103 inter-device comparisons and false authentication attempts. Device fabrication is divided across two separate fabrication facilities, allowing for cross-fab analysis and emulation of a malicious foundry with exact knowledge of the PUF photonic circuit design and process. Our analysis also compares cross-correlation based authentication to the traditional Hamming distance method and experimentally demonstrates an authentication error rate AER = 0%, false authentication rate FAR = 0%, and an estimated probability of cloning below 10−30. This work validates the potential scalability of integrated photonic-PUFs which can attractively leverage mature wafer-scale manufacturing and automated contact-free optical probing. Such structures show promise for authenticating hardware in the untrusted supply chain or augmenting conventional electronic-PUFs to enhance system security.

Optically resonant all-dielectric nanostructures attractively exhibit reduced losses compared to their plasmonic counterparts; however, achieving strong field enhancements at the nanoscale, especially within solid-state media, has remained a significant challenge. In this work, we demonstrate how subwavelength modifications to a conventional silicon nanodisk enable strong sub-diffractive and polarization dependent field enhancements in devices supporting Mie resonances, including anapole-like modes. We examine the electromagnetic properties of both individual and arrayed “diabolo nanodisks,” which are found to exhibit |E|2/|E0|2 enhancements in the range ∼102–104, in the high index medium, depending on geometrical considerations. In addition to supporting a localized electric field “hot-spot” similar to those predicted in diabolo nanostructured photonic crystal cavities and waveguide designs, we identify an anti-diabolo effect leading to a broadband “cold-spot” for the orthogonal polarization. These findings offer the prospect of enhancing or manipulating light–matter interactions at the nanoscale within an all-dielectric (metal free) platform for potential applications ranging from non-linear optics to quantum light sources, nano-sensing, nanoparticle-manipulation, and active/tunable metasurfaces.

We report the design and characterization of sub-wavelength engineered all-dielectric silicon nanodisks supporting localized field enhancements and anapoles in the near infra-red and verify the presence of the resonant mode through polarization resolved reflectance measurements.