Long life Perovskite Nanoplatelet Lasers with high quality factor enabled through engineering degradation pathways

MAPbI3 perovskite has attracted widespread interests for developing low-cost near infrared semiconductor gain media. However, it faces the instability issue under operation conditions, which remains a critical challenge. It is found that the instability of the MAPbI3 nanoplatelet laser comes from the thermal-induced-degradation progressing from the surface defects towards neighboring regions. By using PbI2 passivation, the defect-initiated degradation is significantly suppressed and the nanoplatelet degrades in a layer-by-layer way, enabling the MAPbI3 laser sustain for 4500 s (2.7×107 pulses), which is almost 3 times longer than that of the nanoplatelet laser without passivation. Meanwhile, the PbI2 passivated MAPbI3 nanoplatelet laser with the nanoplatelet cavity displaying a maximum quality factor up to ~7800, the highest reported for all MAPbI3 nanoplatelet cavities. Furthermore, a high stability MAPbI3 nanoplatelet laser that can last for 8500 s (5.1×107 pulses) is demonstrated based on a dual passivation strategy, by retarding the defect-initiated degradation and surface-initiated degradation, simultaneously. This work provides in-depth insights for understanding the operating degradation of perovskite lasers and the dual passivation strategy paves the way for developing high stability near infrared semiconductor laser media.

Sulfophosphate Glass Doped with Er3+ and TiO2 Nanoparticles: Thermo-Optical Characterization by Photothermal Spectroscopy

In this work, time-resolved thermal lens and beam deflection methods were applied to determine the thermo-optical properties of Er3+ doped sulfophosphate glass in which different concentrations of Titanium dioxide (TiO2) nanoparticles (NPs) were embedded. Thermal diffusivity (D), thermal conductivity (κ), and the temperature coefficient of the optical path length (ds/dT) were determined as a function of NPs concentrations. Moreover, the growth of TiO2 NPs inside the amorphous glass matrix was evidenced by Transmission Electron Microscopy (TEM) images as well as through optical effects such as refractive index change of the glass. The outcomes indicated relatively high values for D and κ as well as a low ds/dT as required for most optical components used for laser media. The addition of TiO2 NPs with concentration of dopants up to 0.6 mol% improved the optical properties of the glass samples but did not affect its thermal properties. The results indicate that the enhanced optical and thermal performance of the proposed co-doped glass fits the quality standards for materials used in photonic devices.

Laser destruction of polymeric materials

This work analyzes the properties of polymers, which make them indispensable in the manufacture of elements used in optics, since the main requirement for polymers is stability when exposed to laser radiation. Currently, polymers are used as active laser media. The most commonly used is polymethyl methacrylate, which is highly transparent and the most resistant in relation to laser exposure.

AMPL INTERNATIONAL CONFERENCE (1992–2019) AND ITS ROLEIN THE DEVELOPMENT OF PHYSICS AND TECHNOLOGY OF PULSEDLASERS, AS WELL AS THEIR APPLICATIONS

From September 15 up to September 20, 2019, the regular, 14th International Conference on Pulsed Lasers and Laser Applications – AMPL (abbreviation from the English name Atomic and Molecular Pulsed Lasers) was held in Tomsk. AMPL Conference (https://symp.iao.ru/ru/ampl), which is a periodic scientific event and takes place every two years in the city of Tomsk. The first conference was held in 1992, and all subsequent ones since 1995 took place on odd years. The AMPL conference is traditionally held in mid-September. Conference topics – fundamental issues of laser physics, physicochemical processes in active laser media, new types of lasers and laser systems, the use of lasers in science, technology, medicine, other fields of activity, problems of bringing laser devices and technologies to the market, as well as fundamental and applied issues on the creation and use of spontaneous radiation sources (excilamps). Along with Russian scientists, specialists, graduate students and students, representatives of near and far abroad regularly participate in the conference. The article provides a brief overview of past conferences, notes how the conference topics were expanded and modified in response to the challenges of gaining new knowledge in the field of photonics, as well as the needs of the laser equipment and technology market. An analysis of the current state of fundamental and applied research is given, and trends in the development of laser technologies are discussed.

Структура, генерационные характеристики и фотостабильность новых гетерил-кумаринов

The effect of the structure of a number of new laser media based on heteryl-coumarins on their spectral and lasing characteristics is studied under conditions of coherent nanosecond and microsecond lamp pumping. The effect of triazole, oxadiazole, and thiazole heterocycles in the structure of coumarin molecules on the spectral, lasing, and photochemical properties of their ethanol solutions has been studied. The analysis of the influence of heteroatoms, heterocyclic radicals, and an aryl fragment in the conjugation chain on the electron density distribution in the structure of coumarin molecules is carried out. It was shown, that triazole and oxadiazole heterocycles provide better lasing ability and photostability of the compounds under study, which made it possible to create new laser media generating radiation in the spectral range 490-560 nm with a sufficiently high efficiency.

Экстремальная и топологическая нелинейная оптика открытых систем

A review of results of an investigation of the theory of optical wave packets with extreme properties with respect to a controllable pulse shape or to the complexity of the internal structure of radiation beam pulses is presented. Special attention is paid to the manifestations of dissipative effects of the electromagnetic energy inflow and outflow. Precisely these factors lead to peculiar rules of conservation of purely electromagnetic quantities in dissipative media, in which the electromagnetic energy irreversibly decreases in the case of absorption and increases with gain. These rules impose certain restrictions on the possibility of transformation of the shape of pulses and allow one to qualitative describe their evolution. A higher efficiency of the action of unipolar or quasi-unipolar radiation pulses on classical and quantum microobjects is shown and possible ways of formation of these pulses are discussed. For bulk laser media with saturable absorption, the topological properties of localized radiation structures and their transformations with a smooth change in the parameters of the medium (pump level) are described. The preservation of the topological structure upon changes in parameters within the stability range yields the possibility of their distinguishing when coding information by topological solitons of the considered type.