High-accuracy and high-speed three-dimensional (3D) fringe projection profilometry (FPP) has been widely applied in many fields. Recently, researchers discovered that deep learning can significantly improve fringe analysis. However, deep learning requires numerous objects to be scanned for training data. In this paper, we propose to build the digital twin of an FPP system and perform virtual scanning using computer graphics, which can significantly save cost and labor. The proposed method extracts 3D geometry directly from a single-shot fringe image, and real-world experiments have demonstrated the success of the virtually trained model. Our virtual scanning method can automatically generate 7,200 fringe images and 800 corresponding 3D scenes within 1.5 hours.We demonstrate flexible GaAs photodetector arrays that were hetero-epitaxially grown on a Si wafer for a new cost-effective and reliable wearable optoelectronics platform. A high crystalline quality GaAs layer was transferred onto a flexible foreign substrate and excellent retention of device performance was demonstrated by measuring the optical responsivities and dark currents. Optical simulation proves that the metal stacks used for wafer bonding serve as a back-reflector and enhance GaAs photodetector responsivity via a resonant-cavity effect. Device durability was also tested by bending 1000 times and no performance degradation was observed. This work paves a way for a cost-effective and flexible III-V optoelectronics technology with high durability.Generation and properties of dissipative Kerr solitons and platicons in optical microresonators are studied in the presence of the backscattering using the original analytical model considering a linear forward-backward waves coupling and nonlinear cross-action. We reveal that the backscattering may suppress the generation of the solitonic pulses or destabilize them for both anomalous and normal group velocity dispersion. We also demonstrate the possibility of switching between different soliton states. The influence of the linear and nonlinear coupling is analysed. It is shown that while the impact of the nonlinear coupling on the generation of the bright solitons is rather weak, it is significantly more pronounced for the platicon excitation process.We have experimentally demonstrated the generation of sub-half-cycle phase-stable pulses with the carrier wavelength of 10.2 µm through two-color filamentation in nitrogen. The carrier-envelope phase (CEP) of the MIR pulse is passively stabilized and controlled by the attosecond time delay between the two-color input pulses. The duration of the MIR pulse is 13.7 fs, which corresponds to 0.402 cycles. The absolute value of the CEP of the generated sub-half-cycle pulse is consistent with a simple four-wave difference frequency generation model. We have also found that the 10 kHz repetition rate of the light source causes the fluctuation of the pulse energy on a few hundred millisecond time scale.We investigate the self-healing property of focused circular Airy beams (FCAB), and this property is associated with the transverse Poynting vector (energy flow) for a better interpretation. We both experimentally and numerically show the effect of the obstruction's position, size and shape on the self-healing property of FCAB. It is found that FCAB will heal if the obstruction is placed at the area between the two foci of FCAB, and it has the least influence on the FCAB when the obstruction is placed near the lens' rear focal plane, whereas FCAB cannot heal if the obstruction is out of the area between two foci. Our experimental results are in good agreement with numerical results.Saw-tooth refractive lenses are extremely well-suited to focus high energy X-rays (>50 keV). These lenses have properties of being continuously tunable (in energy or focal length), effectively parabolic, in-line, and attenuation-free on-axis. Vertical focusing of 60 keV synchrotron X-rays to 690 nm at a focal length f = 1.3 m with silicon saw-tooth lenses at a high-energy undulator radiation beamine is demonstrated, with discussion of relevant fabrication and mounting considerations and of geometrical aberrations unique to these devices. Aberration corrections towards further progress into the diffraction-limited nanofocusing regime are suggested. The versatility of such optics, combined with the attainability of smaller spot sizes at these penetrating photon energies, should continue to enhance material microstructure investigations at increasingly higher spatial resolutions.We report an ultralow power consumption of a quantum cascade laser (QCL) emitting at λ ∼ 4.6 µm operating in continuous-wave mode at room temperature. The ultralow power consumption is achieved by using a high gain active region and shortening the device size. For the device with a 0.5-mm-long cavity and 3.2-µm-wide ridge, the threshold power consumption is as low as 0.26 W with an optical output power of 12.6 mW at 10 °C in continuous-wave mode, which represents the world's most advanced level. Furthermore, the threshold power consumption varies linearly with the operating temperature, where the linear change rate of 2.3 mW/K from 10 to 40 °C is low. As a result, the devices also show low threshold power consumption values of 0.33 W even at 40 °C in continuous-wave mode with an optical output power of 6.1 mW. selleck screening library In addition, the lasers can maintain a single-mode operation due to the short cavity length even if no distributed feedback grating is applied.We give the general expressions of intensity-difference squeezing (IDS) generated from two types of optical parametric amplifiers [i.e. phase-sensitive amplifier (PSA) and phase-insensitive amplifier (PIA)] based on the four-wave mixing process, which clearly shows the IDS transition between the ultra-low average input photon number regime and the ultra-high average input photon number regime. We find that both the IDS of the PSA and the IDS of the PIA get enhanced with the decrease of the average input photon number especially in the ultra-low average input photon number regime. This result is substantially different from the result in the ultra-high average input photon number regime where the IDS does not vary with the average input photon number. Moreover, under the same intensity gain, we find that the optimal IDS of the PSA is better than the IDS of the PIA in the ultra-low average input photon number regime. Our theoretical work predicts the presence of strong quantum correlation in the ultra-low average input photon number regime, which may have potential applications for probing photon-sensitive biological samples.