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In addition, a multireflection interference theory is also investigated to quantitatively explain the physical absorption mechanism. Such a tunable broadband absorber based on temperature control has great potential to be applied to sensors, thermophotovoltaics, and wireless communication.We demonstrate a high-power, high-energy chirped-pulse amplification (CPA) system based on three YbYAG amplifiers and a chirped-volume Bragg grating (CVBG). With an all-fiber laser as the seed light, a YbYAG rod amplifier and two YbYAG single-crystal fiber (SCF) amplifiers as the amplification stages, a laser power of 96 W at 200 kHz repetition rate corresponding to a pulse energy of 0.48 mJ has been generated. The stability of different output power has been measured and compared. To the best of our knowledge, this is the first report on a stable 100 W-level laser with sub-mJ pulse energy based on SCF. The beam quality M2 of different output lasers has also been measured, which is below 1.55 when the output power is 92 W. The amplified laser is seeded into the CVBG to be compressed, and a compression efficiency of 0.724 has been obtained with an output power of 67.8 W and pulse duration of 2.5 ps. The ultrafast CPA system delivering high pulse energy (sub-mJ) with hundreds of kHz repetition rate is expected to be used as the driving source of high-flux high-harmonic generation after further compression.We present a precise, portable, and inexpensive Mueller matrix polarimeter based on a pair of twisted nematic liquid crystal plates. Such a design is of interest to low-budget users or to those who require a portable instrument for applications to be carried on outside a laboratory environment. We develop the theoretical model for the proposed polarimeter and describe the complete implementation of the device. This process includes the selection of the optimum states of polarization to perform the measurements, the calibration of the instrument, and the evaluation of its performance for punctual and imaging applications. The proposed device is at least as accurate and precise as similar, but much more expensive, polarimeters.This paper presents a numerical-experimental procedure to characterize through-holes with arbitrary shapes present on metallic substrates under composite material sleeves using pulsed laser shearography and dynamic excitation combined to the finite element method. The so-called fitting process consists of matching experimental and numerical results in order to determine the shape and dimensions of the holes under the composite repair, or even quantify defects between layers of the composite laminate. The results show that the technique is capable of characterizing, in the worst case, the geometry of a hole with 83% accuracy and its respective area with a maximum error of approximately 20%. The advantageous results achieved in this research show that the fitting process can be very useful for real applications in the oil and petroleum industry.We present modeling and analysis of a hysteretic deformable mirror where the facesheet interacts with a continuous layer of piezoelectric material that can be actuated distributively by a matrix of electrodes through multiplexing. [https://www.selleckchem.com/products/gcn2ib.html find more] Moreover, a method to calculate the actuator influence functions is described considering the particular arrangement of electrodes. The results are presented in a semi-analytical model to describe the facesheet's deformation caused by a high-density array of actuators, and validated in a simulation. The proposed modeling of an interconnection layout of electrodes is used to determine the optimal pressures the actuators must exert to achieve a desired surface deformation.A methodology of 3D photolithography through light field projections with a microlens array (MLA) is proposed and demonstrated. With the MLA, light from a spatial light modulator (SLM) can be delivered to arbitrary positions, i.e., voxels, in a 3D space with a focusing scheme we developed. A mapping function between the voxel locations and the SLM pixel locations can be one-to-one determined by ray tracing. Based on a correct mapping function, computer-designed 3D virtual objects can be reconstructed in a 3D space through a SLM and a MLA. The projected 3D virtual object can then be optically compressed and delivered to a photoresist layer for 3D photolithography. With appropriate near-UV light, 3D microstructures can be constructed at different depths inside the photoresist layer. This 3D photolithography method can be useful in high-speed 3D patterning at arbitrary positions. We expect high-precision 3D patterning can also be achieved when a femtosecond light source and the associated multi-photon curing process is adopted in the proposed light field 3D projection/photolithography scheme. Multi-photon polymerization can prevent the unwilling patterning of regions along the optical path before arriving to the designed focal voxels as observed in our single photon demonstrations.Titanium carbide (TiC) nanosheets of two-dimensional multilayer structure were prepared by the liquid-phase exfoliation method. By using the TiC as a saturable absorber, a stable passively Q-switched ErLu2O3 laser at 2.85 µm was realized. Under an absorbed pump power of 7.32 W, the obtained maximum output power was 896 mW with a slope efficiency of 15.6%. The Q-switched pulse duration was measured to be 266.8 ns with repetition rates of 136.9 kHz, corresponding to a peak power of 24.6 W.A photonic-assisted broadband and high-resolution microwave frequency measurement scheme is proposed and demonstrated based on undersampling via using three cavity-less optical pulse sources with coprime repetition rates. After undersampling by three ultrashort pulse trains with repetition rates in the order of gigahertz, input microwave signal is down-converted to three intermediate-frequency (IF) signals located in the first Nyquist frequency range. Through measuring the frequencies of the IF signals via fast Fourier transform after digitization by the commercially available analog-to-digital convertors, the input microwave signal frequency can be retrieved based on the frequency identification algorithm. In the proof-of-concept experiment, three ultrashort pulse trains with repetition rates of 2.99, 3.07, and 3.10 GHz are generated by a cavity-less optical pulse source, where the pulse widths are 9.5, 9.6, and 9.8 ps, respectively. Through using these three ultrashort optical pulse trains, a frequency measurement range up to 40 GHz is realized, where the frequency measurement error is less than ±5kHz, and the spurious-free dynamic range is 91.