Laser stripping of functional coatings on glass fiber reinforced plastic substrate.

Glass fiber reinforced plastic (GFRP) with functional coatings is applied more and more in aircraft, thanks to its light weight and excellent mechanical properties. However, the outermost coating must be removed duo to discoloration, paint dropping, cracking, pits, or other fatigued phenomena after a certain amount of service time. The outermost torn coating on a GFRP material is successfully stripped with a nanosecond laser source. The influences of key laser parameters such as laser power, pulse overlap, and pulse width are studied. Thereafter, an optimized laser processing window is obtained and further validated with specified characterization methods. The repainting and adhesive bonding tests afterward indicate that a laser stripping process is superior to traditional sandpaper polishing because of the effects of surface roughening and microstructure interlocking. A case study further suggests that laser stripping outperforms sandpaper polishing because of its higher efficiency and better quality.

Highly uniform parallel scribing inside transparent materials with ultrafast lasers: from 2D to 3D.

Micromachining uniform features inside transparent materials is of great importance. The generation of highly uniform parallel laser beams based on spatial light modulators is a valid way to realize it. A movable magnifying optical feedback approach is proposed. By using a flip mirror and adjusting a movable stage, magnified 3D information such as energy and the position of the split individual parallel laser beams could be obtained and fed back for optimization. Thanks to this setup, active adjustment of holographic algorithm parameters for the energy uniformity and accurate temporal distribution of the parallel laser beams becomes possible. The feasibility and effectiveness of the proposed method are then demonstrated by laser scribing inside silica glass. We pave a way for uniform 3D laser manipulation and subtle microfabrication.

Design and analysis of a compact subwavelength-grating-assisted 1.55/2 µm wavelength demultiplexer.

The wavelength demultiplexer (deWMUX) is an indispensable component for the wavelength diversity system. In this paper, we propose a subwavelength-grating-assisted ${{1}} \times {{2}}$ deWMUX based on the principle of multimode interference, which aims to output 1.55 and 2 µm wavelengths from two different channels. The simulation results show that the contrast of the designed deWMUX at both wavelengths is greater than 24 dB, the insertion loss is less than 0.5 dB, and the 1 dB bandwidth is wider than 100 nm. In addition, the manufacturing tolerances of the device are also studied.

Comparison of the sensitivity by SPR in a metal-ITO-BlueP/TMDC structure.

A surface plasmon resonance (SPR) sensor based on blue phosphorus (BlueP)/transition metal dichalcogenides (TMDCs) of two-dimensional (2D) materials is proposed to increase the performance. In this sensor, BlueP/TMDCs are coated on indium tin oxide (ITO) and different metals (Au/Ag/Cu) to improve the sensitivity. By optimizing structural parameters, with the BlueP/WS2 monolayer and Au thin film, the angular sensitivity can reach as high as 226.0°/RIU. The phase sensitivity also can be as high as 3.6001×106deg/RIU with BlueP/MoS2 4 layers, 228 nm ITO, and 25 nm Au thin film, which is 6.77 times that of the Au-ITO structure and 54.40 times that of the traditional SPR of Au thin film. The SPR sensor has potential applications in disease diagnosis, drug development, gene sequencing and treatment, environmental monitoring, food safety testing, doping testing, and other fields.

Variable single-passband narrowband optical filter based on forward stimulated interpolarization scattering in photonic crystal fiber.

A variable transmission spectrum single-passband narrowband optical filter is proposed and experimentally demonstrated. It is based on forward stimulated interpolarization scattering (SIPS) in a photonic crystal fiber by applying a differential quadrature phase-shift keying modulation to the pump wave to broaden and shape the SIPS gain spectrum. By choosing the bit rate of the modulation data pattern, a flat-top steep-cutoff optical bandpass filter with a 3 dB bandwidth of 70 MHz and a 10 dB bandwidth of 90 MHz is realized. In addition, a variable narrowband optical notch filter is also realized by attenuation of the pump wave.