Graphene is a useful saturable absorber in a variety of lasers working in mode-locking or Q-switch regimes. The optical performance of chemically synthesized graphene is still not completely characterized. In this study, the saturable absorption and the nonlinear refractive index of graphene flakes in N-methylpyrrolidone, in both liquid and solid phases, have been studied at 800 nm with the z-scan technique using femtosecond laser pulses. The results obtained using a Ti:sapphire laser oscillator in the mode-locking regime (6 fs, 78 MHz) or in the continuous wave shows that the optical properties of graphene have a thermal origin, while at the lower repetition rate and higher energy and intensity of a Ti:sapphire amplifier (95 fs, 1 kHz), it shows the electronic Kerr effect. Solid samples with very high optical densities, equivalent to 60 layers of graphene grown by chemical vapor deposition (CVD), can be fabricated. They show a higher saturation intensity ($I_s\approx 100$ GW cm^–2) than CVD-grown (74 MW cm^–2) or epitaxially grown (4 GW cm^–2) graphene and intensity-dependent changes in transmission from 25% to 43%. This change in transmission in multilayer solid samples points to a good performance as a saturable absorber in laser cavities.

At a time when miniaturization and optimization of resources are in the foreground, the development of devices that can perform various functions is a primary goal of technological development. In this work, the use of an Erbium-Doped Fiber Laser (EDFL) is proposed as a basic system for the generation of an optical logic gate. Taking advantage of the dynamic richness of this type of laser and its use in telecommunication systems, the dynamic response is analyzed when the system is perturbed by a digital signal. The emission response of the system is controlled by the intensity of the digital signal, so that it is possible to obtain different logic operations. The numerical results are in good agreement with the experimental observations. The presented work raises new aspects in the use of chaotic systems as a means of obtaining optical logic gates.

In this paper, the stabilization and high efficiency of an unstable Second Harmonic Generation (SHG) of an $Nd:YV{O}_4$ laser with a KTP intracavity is demonstrated. By using a passive Q-switching crystal ($C{r}^{4+}:YAG$) and a parametric modulation method (harmonic modulation), the stabilization of the laser is reached. An harmonic modulation was applied to the pumping of the $Nd:YV{O}_4$-KTP laser to control the amplitude and frequency of the laser emission. The results were characterized by using power spectra analysis, optical spectrum, bifurcation diagrams, and temporal series of the laser intensity. The promising application of this green light source is materialized when such light is necessary for high-density optics, such as in the treatment materials industry or in some aesthetic applications.

In this article, the methods for obtaining time series from an erbium-doped fiber laser (EDFL) and its numerical simulation are described. In addition, the nature of the obtained files, the meaning of the changing file names, and the ways of accessing these files are described in detail. The response of the laser emission is controlled by the intensity of a digital signal added to the modulation, which allows for various logical operations. The numerical results are in good agreement with experimental observations. The authors provide all of the time series from an experimental implementation where various logic gates are obtained.

A logic gate is typically an electronic device with a Boolean or other type of function, e.g., adding or subtracting, including or excluding according to its logical properties. They can be used in electronic, electrical, mechanical, hydraulic, and pneumatic technology. This paper presents a new method for generating logic gates based on optical systems with an emission frequency equal to that used in current telecommunications systems. It uses an erbium-doped fiber laser in its monostable operating region, in contrast to most results published in the literature, where multistable behavior is required to induce dynamic changes, and where a DC voltage signal in the laser pump current provides the control between obtaining the different logic operations. The proposed methodology facilitates the generation of the gates, since it does not require taking the optical system to critical power levels that could damage the components. It is based on using the same elements that the EDFL requires to operate. The result is a system capable of generating up to five stable and robust logic gates to disturbances validated in numerical simulation and experimental setup. This eliminates the sensitivity to the initial conditions affecting the possible logic gates generated by the system and the need to add noise to the system (as is performed in works based on stochastic logic resonance). The experimental observations confirm the numerical results and open up new aspects of using chaotic systems to generate optical logic gates without bistable states.