In this paper we present an experimental set-up for measuring small frequency differences between two RF oscillators  by using a homodyne detection scheme . To emulate the oscillators, we used two RF sources whose output signals were mixed and then the low frequency components at the mixer's output was measured with a network frequency analyzer. The purpose of these experiments was to evaluate a possible method to discriminate the resonance frequency change of a TF-BAR sensor as a response to its contamination with certain substances.
In this paper is described 3D simulation for solitions used in optical fibers. In the scientific works is started from nonlinear propagation equation and the solitons represents its solutions. This paper presents the simulation of the fundamental soliton in 3D together with simulation of the second order soliton in 3D. These simulations help in the study of the optical fibers for long distances and in the interactions between the solitons. This study helps the understanding of the nonlinear propagation equation and for nonlinear waves. These 3D simulations are obtained using MATLAB programming language, and we can observe fundamental difference between the soliton and the second order/higher order soliton and in their evolution.
In this paper we present one model for parameters used in EDFA (Erbium Doped Fiber Amplifier) in the case of high-
power limit. We use for this model the absorption and emission cross-sections as a function of wavelength. In this model
we use the fraction of Er3+ ions in the excited state as a function of wavelength for high-power limit. In addition, we
present and compare these characteristics for different erbium-doped glasses in the case of EDFA. The results obtained
here can be used to evaluate and to determine the characteristics for noise figure and for gain in the case of EDFA.
There is presented a simple method to obtain the pumping temperature Tp for EDFA. We propose the analytical method to obtain the pumping temperature for EDFA (Erbium Doped Fiber Amplifier). We have obtained the pumping temperature of EDFA by varying the voltage parameter VTEMP in the following interval VTEMP ε (0 ÷ 2.5). With these sets of values we calculated the pumping temperature Tp of the EDFA as a function of VTEMP.
We propose a simple method for integration by numerical computations of the atomic rate equations for three-level systems and the laser amplifier equations. We calculate the gain coefficient in erbium-doped fiber considering the effects of pump on the system dynamics. Described the atomic rate equations for three-level system and the dynamics Maxwell-Bloch equations for erbium-doped fiber laser amplifier is presented.