Versatile VCSEL source of thermal and super-thermal light.

We have built highly controllable sources of thermal and super-thermal states on the basis of a single-mode (SM) and a multi-mode (MM) vertical cavity surface emitting laser (VCSEL) with noised driving current operating above the threshold. Varying the average driving current and the amplitude and bandwidth of noise, one can robustly obtain light with the temporal second-order intensity correlation function reaching 2.5 and correlation times from 1 µs to 10 ns.

Improvement of signal propagation in the optoelectronic artificial spiking neuron by vibrational resonance.

Experimental evidence of vibrational resonance (VR) in the optoelectronic artificial spiking neuron based on a single photon avalanche diode and a vertical cavity laser driven by two periodic signals with low and high frequencies is reported. It is shown that a very weak subthreshold low-frequency (LF) periodic signal can be greatly amplified by the additional high-frequency (HF) signal. The phenomenon shows up as a nonmonotonic resonant dependence of the LF response on the amplitude of the HF signal.

Photostability and phototoxicity of graphene quantum dots interacting with red blood cells.

Here we discuss fluorescent properties of graphene quantum dots (GQDs) interacting with the membranes of red blood cells. We report the results of spectroscopic, microscopic, and photon-counting measurements of the GQDs in different surroundings for uncovering specific features of the GQD fluorescence, and describe two observed phenomena important for implementation of the GQDs as fluorescent labels and agents for drug delivery. Firstly, the GQDs can suffer from photodegradation but also can be stabilized in the presence of antioxidants (reduced glutathione, N-acetylcysteine, or 1,4-hydroquinone).

Hysteresis and Stochastic Fluorescence by Aggregated Ensembles of Graphene Quantum Dots.

"Blinking" behavior of fluorophores, being harmful for the majority of super-resolved techniques, turns into a key property for stochastic optical fluctuation imaging and its modifications, allowing one to look at the fluorophores already used in conventional microscopy, such as graphene quantum dots, from a completely new perspective. Here we discuss fluorescence of aggregated ensembles of graphene quantum dots structured at submicron scale. We study temperature dependence and stochastic character of emission.

Amplification of optical signals in a bistable vertical-cavity surface-emitting laser by vibrational resonance.

The paper presents the results of the experimental study of an application of the phenomenon of vibrational resonance (VR) for enhancement of the response of a bistable vertical-cavity surface-emitting laser (VCSEL) to the effect of optical modulating signals. Specifically, two different cases were investigated: (a) the control of all-optical switching caused by a modulated orthogonal optical injection from another VCSEL and (b) the amplification of autodyne signals from a vibrating diffusely reflecting surface in the self-mixing optical interferometry. It is experimentally demonstrated that an application of the phenomenon of VR in both cases studied leads to a strong amplification of the input optical signals by a factor from 10 to 200 depending on the experimental conditions with respect to the initial values.