High average power (105†W) Fe:ZnSe laser pumped by radiation of laser diode side-pumped Er:YAG lasers.

A high average power re-frequency operation Fe:ZnSe laser using laser diode side-pumped free-running Er:YAG lasers as activating sources is presented. Two pieces of subsurface layer doped Fe:ZnSe polycrystal are adoptive in a reflective resonator configuration and face-cooled by liquid nitrogen. A maximal Fe:ZnSe laser power of 105 W at a wavelength of 4.1 µm is achieved upon pumping by ten home-made Er:YAG lasers with fiber coupled output working at a frequency of 250 Hz and a pulse duration of ∼420 µs. Corresponding to the maximum Fe:ZnSe laser power, the optical-optical efficiency and slope efficiency with respect to the absorbed pump power are 43% and 44% respectively. The beam quality factor M2 is measured to be 3.4. To the best of our knowledge, it is the highest output average power of an Fe:ZnSe laser reported.

Copper electrode preparation by a selective laser reduction of copper oxide on lignin fiber membranes and its application as a photodetector.

The performance of electrodes is a key factor affecting the development of smart fabrics. The preparation of common fabric flexible electrodes has defects such as high cost, complicated preparation, and complex patterning that limit the development of fabric-based metal electrodes. Therefore, this paper presented a simple fabrication method for preparing Cu electrodes using selective laser reduction of CuO nanoparticles. By optimizing laser processing power, scanning speed, and focusing degree), we prepared a Cu circuit with an electrical resistivity of ∼ 5.53 µΩ.m. Based on the photothermoelectric properties of Cu electrodes, a white light photodetector is developed. The detectivity of the photodetector reaches ∼2.14 mA/W at a power density of 10.01 mW/cm2. This method is instructive for preparing metal electrodes or conductive lines on the surface of fabrics, and provides specific techniques for manufacturing wearable photodetectors.

Nitrogen-doped graphene quantum dots synthesized by femtosecond laser ablation in liquid from laser induced graphene.

In this work, graphene quantum dots (GQDs) were synthesized by femtosecond laser ablation in liquid using laser induced graphene as the carbon source. Nitrogen-doped graphene quantum dots (N-GQDs) were successfully synthesized by adding ammonia water to the graphene suspension. The GQDs/N-GQDs structure consist of a graphitic core with oxygen and nitrogen functionalities with particle size less than 10 nm, as demonstrated by x-ray photoelectron spectroscopy, Fourier infrared spectrometer spectroscopy, and transmission electron microscopy. The absorption peak, PL spectrum, and quantum yield of the N-GQDs were significantly enhanced compared with the undoped GQDs. Further, the possible mechanism of synthesis GQDs was discussed. Furthermore, the N-GQDs were used as a fluorescent probe for detection of Fe3+ions. The N-GQDs may extend the application of graphene-based materials to bioimaging, sensor, and photoelectronic.

Direct Laser Writing of Transparent Polyimide Film for Supercapacitor.

Direct laser writing (DLW) is a convenient approach for fabricating graphene-based flexible electronic devices. In this paper, laser-induced graphene was successfully prepared on a thin and transparent polyimide film through the DLW process. Experiments have demonstrated that interdigital thin film capacitor prepared by the DLW method has a high specific capacitance of 8.11 mF/cm2 and volume capacitance density of 3.16 F/cm3 (0.05 mA/cm2) due to the doped fluoride in the laser-induced graphene. The capacitance is about 20 times larger than the super-capacitor based non-transparent polyimide film of the same thickness. Owing to its thin, flexible, higher electrochemical characteristics, the transparent polyimide film is promising for integrating and powering portable and wearable electronics.