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A laser etching method was performed to achieve the dual purpose of fabricating grating structures and laser annealing on aluminum-doped zinc oxide (AZO) thin films, and thus improve the film photoelectric performances. Different line spacings and laser fluences were adopted to systematically explore the optimal laser etching condition. Too narrow line spacings or too high laser fluences led to light reflections at the grating external surface to cause more light dissipation, and too wide line spacings or too low laser fluences resulted in relatively small total grating lateral areas being detrimental to multiple internal light reflections. Moreover, too narrow line spacings brought about laser-caused lattice disorder and too high laser fluences produced laser-ablated spots or overburned traces. Therefore, using the medium line spacing and laser fluence, e.g. 40 μm and 0.6 J/cm2 in the present work, was more suitable for synchronously realizing grating structure fabrication and laser annealing. The corresponding AZO film exhibited the maximum figure of merit of 2.89 × 10−2 Ω−1, which was 1.6 times that of the untreated AZO film. This study is expected to expand performance improvement methods of TCO films and promote the application of laser-etched grating structures.

Silver (Ag) films were deposited on glass substrates by radio frequency (RF) magnetron sputtering and then ablated by a 532 nm nanosecond pulsed laser. The effects of laser fluence and defocusing amount on the width and depth of laser-ablated grooves on 100- and 600-nm-thick Ag films were systematically investigated under single- and multi-scan ablation. The results suggested that the Ag films could be successfully removed from the substrate owing to laser-induced thermoelastic force or vaporization. It was confirmed that laser fluence and defocusing amount played very important roles in controlling the width and depth of the laser-ablated grooves. In the present work, grooves with widths ranging from 53 to 196 μm and depths ranging from 56 to 196 nm were obtained on 100-nm-thick Ag films by single-scan laser ablation, and laser ablation or removal with controllable depths was realized on 600-nm-thick Ag films by adopting single- or multi-scan (i.e., scanning numbers of 1–6). Furthermore, square spiral Ag patterns were successfully obtained by single- and multi-scan laser ablation and showed good electrical conductivity in a simple circuit. This work may have great potential applications in various fields that demand width and depth control of laser ablation/removal.

An ultrasonic-vibration-assisted laser annealing method was developed to enhance the performance of fluorine-doped tin oxide (FTO) thin films. The influences of ultrasonic vibration, laser scan line overlapping rate (LOR) and laser spot overlapping rate (SOR) on surface morphology, FTO layer thickness, RMS roughness, crystal structure and photoelectric properties of the FTO films were investigated. The results indicated that the presence of ultrasonic vibration during laser annealing could significantly enhance the film compactness, and using moderate LOR and SOR values resulted in significantly decreased FTO layer thicknesses and RMS roughnesses as well as slightly increased crystallite sizes, thus yielding significantly improved optical transmittance values and slightly enhanced electrical conductivity values. It was found that the optimal LOR and SOR values for ultrasonic-vibration-assisted laser annealing of the FTO films were 80% and 90%, respectively. The as-obtained film possessed the best overall photoelectric property with an average transmittance (400–800 nm) of 85.9%, a sheet resistance of 8.7 Ω/sq and a figure of merit of 2.51 × 10–2 Ω–1. This work may be of great significance in terms of performance optimization of transparent conducting oxide (TCO) thin films.

A new ultrafast laser direct writing process to fabricate completely embedded silver mesh flexible transparent electrodes (TEs) using sputtered silver thin films and their applications for flexible transparent heaters (FTHs) are reported. The optimal laser etching parameters were determined, and the effects of mesh pitch and height on photoelectric properties of the silver mesh flexible TEs were systematically studied, with an aim to obtain a TE with excellent comprehensive performance. The resulting TE had a lower sheet resistance (0.86 Ω/sq) and a higher optical transmittance (91.26%) than traditional TEs. Good environmental stability of the TE, i.e. maintaining good electrical conductivity in air or deionized water without significant changes for 40 days, was also demonstrated. The fabricated representative FTH also presented stable heating performance, reaching a high temperature in 60 s under a DC voltage of 1.0 V and finally stabilizing at 98 ℃. This heating performance was confirmed to be stable and consistent after 20 cycles or under the conditions of bending and twisting. In addition, a deicing experiment was performed to illustrate the possible application of the FTH. The results indicated the availability of the laser direct writing method for fabricating high-performance metal mesh-based flexible TEs.

This work focuses on the fabrication of antireflection grating structures on Ag/F-doped SnO2 (FTO) films by ultrasonic-vibration-assisted laser irradiation to compensate the optical transmittance loss due to coating the Ag layers. The effects of laser fluence and ultrasonic vibration on formation of laser-induced grating structures are investigated. The results indicate that ultrasonic-vibration-assisted laser irradiation can not only contribute to generating a complete and uniform periodic grating structure, it can also bring about a laser annealing effect to the film. Ultrasonic vibration is considered to play an important role in generating the grating structure by changing the defocusing amount of the film surface, inputting energy and providing mechanical vibration. Moreover, under the favorable influence of ultrasonic vibration, the laser parameter values can be lowered, and the interference of the laser-excited surface plasmons (SPs) with the incident laser can be facilitated. In this present work, the optimal grating-structured Ag/FTO film has the highest figure of merit of 3.26 × 10−2 Ω−1, showing significant increases compared to the untreated FTO (1.13 × 10−2 Ω−1) and the ultrasonic-vibration-free laser-irradiated Ag/FTO (2.34 × 10−2 Ω−1) films. This work may be of important enlightening and reference significance for preparing high-performance transparent conductive films.

To further improve electrical performance of FTO single-layer films and obtain high-performance transparent electrodes, the effects of silver (Ag) layer thickness and scan line spacing on optical and electrical properties of Ag/F-doped SnO2 (FTO) bilayer composite thin films prepared by radio frequency (RF) magnetron sputtering and ultrasonic-vibration-assisted laser annealing were investigated. The results indicate that as compared to the untreated FTO single-layer film, the Ag/FTO composite film displays a dramatic decrease in sheet resistance with even an improvement in transparency when the Ag layer thickness reaches 5 nm under the combined effect of laser annealing and ultrasonic vibration. Furthermore, the XRD and SEM analyses reveal that only using the moderate scan line spacing during ultrasonic-vibration-assisted laser annealing can contribute to the grain growth of the films. The Ag/FTO film with an Ag layer thickness of 5 nm and a scan line spacing of 20 μm shows a remarkable overall performance with an increased figure of merit of 2.13 × 10−2 Ω−1 comparing to 1.13 × 10−2 Ω−1 for the untreated FTO film. This work confirms the opportunity of combining Ag layer deposition and ultrasonic-vibration-assisted laser annealing in significantly improving both optical and electrical properties of FTO single-layer films, providing a promising alternative to the conventional ITO transparent electrodes.

Laser shock processing induced structural transformation in graphite cluster of about 3 nm diameter is simulated through molecular dynamics simulations. The Brenner potential is utilized to characterize short-range order while Lennard-Jones potential for long-range order. The effect of high-energy laser shock on graphite was simulated with corresponding temperature and pressure load applied to the graphite cluster. The graphite cluster was found to transform into nano-diamond, crystal structures and amorphous carbon after heating–pressing and annealing–decompression by analyzing pair distribution function g(r) and atomic snapshots process. An interesting mechanism ‘direct transfer-adsorption’ for promoting peripheral carbon atoms of the graphite cluster into the inner layer and transforming bonds from sp2-type to sp3-type within the inner carbon atoms is investigated. The ‘direct transfer-adsorption’ mechanism, which prevails under the conditions of a temperature higher than 4300 K and a pressure higher than 15 GPa, is at fast cooling rates and high densities. And the ‘direct transfer-adsorption’ mechanism plays a key role in the conversion from graphite to diamond.

A new method of optical image encryption with binary Fourier transform computer-generated hologram (CGH) and pixel-scrambling technology is presented. In this method, the orders of the pixel scrambling, as well as the encrypted image, are used as the keys to decrypt the original image. Therefore, higher security is achieved. Furthermore, the encrypted image is binary, so it is easy to be fabricated and robust against noise and distortion. Computer simulation results are given to verify the feasibility of this method and its robustness against occlusion and additional noise.