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This work exploits terahertz (THz) imaging in the real-space and the spatial-frequency domain to determine nondestructively the evolution of the main characteristics of a woven glass-fiber reinforced polymer laminate in three-dimensions in situ during a tensile test. These characteristics include tow orientation and the weave period. The surface and the inner plies can be investigated with the proposed method. The results show how the tows tend to realign with the load direction. In addition, we detect a decrease in the weave period, manifesting a distortion of the surface and inner layers as the stress is increased. Contrary to conventional optical inspection, THz inspection can provide quantitative measurements in all material layers and not only on the surface. This technique could be helpful to monitor distortion and damage due to mechanical stress or defects incorporated during the manufacturing process and to validate parameters and results of draping process modeling, especially for the inner plies.

We analyze the performance of a reservoir computer based on time-delay feedback and optical injection, which is drawing benefits from the high-speed polarization dynamics of a vertical cavity surface emitting laser. We show that such a system has high computation performance and yields deeper memory than an existing single-mode laser-based reservoir computer. Performance is demonstrated on several benchmarking tasks. In particular, the error rate is an order of magnitude smaller when performing channel equalization.

We report on the occurrence of extreme events (EEs) in the polarization dynamics of vertical cavity surface emitting lasers with optical feedback. We have identified two types of EEs based on numerical simulations: vectorial and scalar events corresponding, respectively, to the emission of a high-power pulse in both linear polarizations simultaneously and in single linear polarization. We show that these two types of events follow the typical statistics of rogue waves. Finally, we observe that an emission in both polarizations leads to a larger generation rate of EEs with a saturation over a wide range of feedback strength by comparison to a single-polarization mode emission.

We demonstrate experimentally how to harness quasi-periodic dynamics in a semiconductor laser with dual optical feedback for measuring subwavelength changes in each arm of the cavity simultaneously. We exploit the multifrequency spectrum of quasi-periodic dynamics and show that independent frequency shifts are mapped uniquely to two-dimensional displacements of the arms in the external cavity. Considering a laser diode operating at telecommunication wavelength λ≈1550  nm, we achieve an average nanoscale resolution of approximately 9.8 nm (∼λ/160).