UV-A Flexible LEDs Based on Core-Shell GaN/AlGaN Quantum Well Microwires.

Nanostructured ultraviolet (UV) light sources represent a growing research field in view of their potential applications in wearable optoelectronics or medical treatment devices. In this work, we report the demonstration of the first flexible UV-A light emitting diode (LED) based on AlGaN/GaN core-shell microwires. The device is based on a composite microwire/poly(dimethylsiloxane) (PDMS) membrane with flexible transparent electrodes.

Fast switching between the ground- and excited-state lasing in a quantum-dot microdisk triggered by sub-ps pulses.

A quantum-dot microdisk was optically pumped by continuous-wave excitation with a level sufficient for the ground-state lasing. The microdisk was additionally illuminated with sub-ps pulses of various powers. It was found that there is a critical level of pulse power that determines the subsequent transient process of the microlaser.

Two-state lasing in a quantum dot racetrack microlaser.

The peculiarities of two-state lasing in a racetrack microlaser with an InAs/GaAs quantum dot active region are investigated by measuring the electroluminescence spectra at various injection currents and temperatures. Unlike edge-emitting and microdisk lasers, where two-state lasing involves the ground and first excited-state optical transitions of quantum dots, in racetrack microlasers, we observe lasing through the ground and second excited states. As a result, the spectral separation between lasing bands is doubled to more than 150 nm.

Elastic Gallium Phosphide Nanowire Optical Waveguides-Versatile Subwavelength Platform for Integrated Photonics.

Emerging technologies for integrated optical circuits demand novel approaches and materials. This includes a search for nanoscale waveguides that should satisfy criteria of high optical density, small cross-section, technological feasibility and structural perfection. All these criteria are met with self-assembled gallium phosphide (GaP) epitaxial nanowires.

Temperature Evolution of Two-State Lasing in Microdisk Lasers with InAs/InGaAs Quantum Dots.

One-state and two-state lasing is investigated experimentally and through numerical simulation as a function of temperature in microdisk lasers with Stranski-Krastanow InAs/InGaAs/GaAs quantum dots. Near room temperature, the temperature-induced increment of the ground-state threshold current density is relatively weak and can be described by a characteristic temperature of about 150 K. At elevated temperatures, a faster (super-exponential) increase in the threshold current density is observed.