Using porous silicon (PSi) interferometer sensors, we show the first experimental implementation of the high contrast cleavage detection (HCCD) mechanism. HCCD makes use of dramatic optical signal amplification caused by cleavage of high-contrast nanoparticle labeled reporters instead of the capture of low-index biological molecules. An approximately 2 nm reflectance peak shift was detected after cleavage of DNA-quantum dot reporters from the PSi surface via exposure to a 12.5 nM DNase enzyme solution. This signal change is 20 times greater than the resolution of the spectrometer used for the interferometric measurements, and the interferometric measurements agree with the response predicted by simulations and fluorescence measurements. These proof of principle experiments show a clear path to achieving a real-time, highly sensitive readout for a broad range of biological diagnostic assays that generate a signal via nucleic acid cleavage triggered by specific molecular binding events.

We propose LightHash, the first feasible photonic cryptographic hash function for blockchain technology using programmable photonic networks. We experimentally evaluate LightHash and assess whether photonic circuits can outperform digital competitors in latency and energy efficiency.

As blockchain technology and cryptocurrency become increasingly mainstream, photonic computing has emerged as an efficient hardware platform that reduces ever-increasing energy costs required to verify transactions in decentralized cryptonetworks. To reduce sensitivity of these verifications to photonic hardware error, we propose and experimentally demonstrate a cryptographic scheme, LightHash, that implements robust, low-bit precision matrix multiplication in programmable silicon photonic networks. We demonstrate an error mitigation scheme to reduce error by averaging computation across circuits, and simulate energy-efficiency-error trade-offs for large circuit sizes. We conclude that our error-resistant and efficient hardware solution can potentially generate a new market for decentralized photonic blockchain.

Aluminium rods with different copper sheath thicknesses were processed by severe plastic deformation at room temperature and then annealed, to join the constituent metals and produce a nanocrystalline microstructure. A study of the effects of the deformation parameters, copper cladding thickness and annealing temperature on the electrical conductivity and hardness of the conductors is reported. It is shown that an interface forms between constituents because of intermixing in the course of severe shear deformation under high hydrostatic pressure and diffusion during the subsequent annealing. The effective conductivity of the aluminium copper-clad conductor dropped after deformation, but was recovered during annealing, especially during short annealing at 200 • C, to a level exceeding the theoretically predicted one. In addition, the annealing resulted in increased hardness at the interface and copper sheath.

Photonic biosensors that use optical resonances to amplify signals from refractive index changes offer high sensitivity, real-time readout, and scalable, low-cost fabrication. However, when used with classic affinity assays, they struggle with noise from nonspecific binding and are limited by the low refractive index and small size of target biological molecules. In this Letter, we evaluate the performance of an integrated microring photonic biosensor using the high contrast cleavage detection (HCCD) mechanism, which we recently introduced. The HCCD sensors make use of dramatic optical signal amplification caused by the cleavage of large numbers of high-contrast nanoparticle reporters instead of the adsorption of labeled or unlabeled low-index biological molecules. We evaluate the advantages of the HCCD detection mechanism over conventional target-capture detection techniques with the same label and the same sensor platform, using an example of a silicon ring resonator as an optical transducer decorated with silicon nanoparticles as high-contrast reporters. In the practical realization of this detection scheme, detection specificity and signal amplification can be achieved via collateral nucleic acid cleavage caused by enzymes such as CRISPR Cas12a and Cas13 after binding to a target DNA/RNA sequence in solution.