CdSe and CsPbBr3 Quantum Dots Co-doped Monolithic Glasses as Tunable Wavelength Convertors

CdSe and CsPbBr3 quantum dots are well studied photoluminescent materials due to their extraordinary emission properties. However, their vulnerability against environmental conditions limits their integration into further applications. At this point, glass encapsulation offers promising durability features due to its robust and dense structure. In this study, CdSe and CsPbBr3 QDs are successfully synthesized in the same glass host through melt-quenching technique followed by a single heat-treatment process. Excitation wavelength dependent photoluminescence properties are investigated and emission color tunability of monolithic glasses from yellow-green to red is demonstrated. Favorable quantum yield values are obtained as 21.78% and 16.63% under 345 and 365 nm excitation wavelengths, respectively. Prepared glasses demonstrate high potential to be used as tunable wavelength convertors for state-of-the-art photonic and opto-electronic applications.

Highly efficient blue light-emitting diodes with tunable wavelength using vertically graded bandgap quasi-2D perovskite films

Metal halide perovskite materials have emerged as a unique class of solution process compatible semiconductors and alluring candidates for high-performance optoelectronic applications1,2,3, especially light-emitting diodes (LEDs), owing to high quantum efficiency, facile color tunability, narrow emission line widths, as well as cost-effectiveness4,5,6. Despite of the great successes on green and red perovskite LEDs (PeLEDs), the advancement of external quantum efficiency (EQE) of blue PeLEDs still lags far behind those of green and red PeLEDs7,8. Here, we demonstrate color-tunable blue PeLEDs devices with high EQE of 16.1% and 10% for emission wavelengths of 472 nm and 461 nm, respectively. The efficient tunable wavelength electroluminescence (EL) and high (EQE) originate from the optimization of the recombination zone position to reach the charge injection balance in the vertically graded bandgap quasi-2D perovskite materials. Under the synergetic effect of lead chloride (PbCl2) doping and propane-1,3-diammonium (PDABr2) incorporation, the vertically graded bandgap perovskite materials can be prepared by the self-regulation of the reduced-dimensional perovskite during the annealing process. Our work here has significantly elevated the performance of the current blue PeLEDs. It opens up a novel avenue to fabricate high-performance blue PeLEDs that can match up the performance of the green and red PeLEDs for future lighting and display applications.

Narrow-Linewidth 2 μm All-Fiber Laser Amplifier with a Highly Stable and Precisely Tunable Wavelength for Gas Molecule Absorption in Photonic Crystal Hollow-Core Fibers

In recent years, mid-infrared fiber lasers based on gas-filled photonic crystal hollow-core fibers (HCFs) have attracted enormous attention. They provide a potential method for the generation of high-power mid-infrared emissions, particularly beyond 4 μm. However, there are high requirements of the pump for wavelength stability, tunability, laser linewidth, etc., due to the narrow absorption linewidth of gases. Here, we present the use of a narrow-linewidth, high-power fiber laser with a highly stable and precisely tunable wavelength at 2 μm for gas absorption. It was a master oscillator power-amplifier (MOPA) structure, consisting of a narrow-linewidth fiber seed and two stages of Thulium-doped fiber amplifiers (TDFAs). The seed wavelength was very stable and was precisely tuned from 1971.4 to 1971.8 nm by temperature. Both stages of the amplifiers were forward-pumping, and a maximum output power of 24.8 W was obtained, with a slope efficiency of about 50.5%. The measured laser linewidth was much narrower than the gas absorption linewidth and the wavelength stability was validated by HBr gas absorption in HCFs. If the seed is replaced, this MOPA laser can provide a versatile pump source for mid-infrared fiber gas lasers.