Biblio

As more and more information systems rely sen-sors for their critical decisions, there is a growing threat of injecting false signals to sensors in the analog domain. In particular, LightCommands showed that MEMS microphones are susceptible to light, through the photoacoustic and photoelectric effects, enabling an attacker to silently inject voice commands to smart speakers. Understanding such unexpected transduction mechanisms is essential for designing secure and reliable MEMS sensors. Is there any other transduction mechanism enabling laser-induced attacks? We positively answer the question by experimentally evaluating two commercial piezoresistive MEMS pressure sensors. By shining a laser light at the piezoresistors through an air hole on the sensor package, the pressure reading changes by ±1000 hPa with 0.5 mW laser power. This phenomenon can be explained by the photoelectric effect at the piezoresistors, which increases the number of carriers and decreases the resistance. We finally show that an attacker can induce the target signal at the sensor reading by shining an amplitude-modulated laser light.

In this paper, we use selective laser melting (SLM) technology to fabricate AlNiCo magnetic materials, and the effects of laser processing parameters on the density and mechanical properties of AlNiCo magnetic materials were studied. We tested the magnetic properties of the heat-treated magnets. The results show that both laser power and scanning speed affect the forming. In this paper, the influence of laser power on the density of samples far exceeds the scanning speed. Through the experiment, we obtained the optimal range of process parameters: laser power (150 170W) and laser scanning speed (800 1000mm/s). Although the samples formed within this range have higher density, there are still many cracks, further research work should be done.

For exploiting multimode fiber optic communication networks towards physical layer security, we have trained a neural network performing mode decomposition of 10 modes. The approach is based on intensity-only camera images and works in real-time.

When vertically aligned carbon nanotube arrays (CNT forests) are heated by optical, electrical, or any other means, heat confinement in the lateral directions (i.e. perpendicular to the CNTs' axes), which stems from the anisotropic structure of the forest, is expected to play an important role. It has been found that, in spite of being primarily conductive along the CNTs' axes, focusing a laser beam on the sidewall of a CNT forest can lead to a highly localized hot region-an effect known as ``Heat Trap''-and efficient thermionic emission. This unusual heat confinement phenomenon has applications where the spread of heat has to be minimized, but electrical conduction is required, notably in energy conversion (e.g. vacuum thermionics and thermoelectrics). However, despite its strong scientific and practical importance, the existence and role of the lateral heat confinement in the Heat Trap effect have so far been elusive. In this work, for the first time, by using a rotating elliptical laser beam, we directly observe the existence of this lateral heat confinement and its corresponding effects on the unusual temperature rise during the Heat Trap effect.