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The mode competition in Er-doped fiber (EDF) Bragg grating (FBG) fiber laser is researched experimentally, the effect of the operating temperature of FBG on the oscillation mode is discussed. Experiment results demonstrate that the lasing oscillation mode is limited by the bandwidth of FBGs, which is a function of operation temperature, the temperature sensitivity is $1.29\times 10^{-5}{∕}^{\circ }\mathrm{\text{C}}$. When the operating temperature of the two FBGs is 25${}^{\circ }$C, the output power of $-23.69$ dBm and the lasing wavelength of 1549.96 nm with slope efficiency of 0.006% and threshold power of 154 mW are obtained.

The laser intensity Langevin equations for a two-mode ring laser subject to both pump noise and quantum noise have been obtained by a phase-locking method. By means of stochastic simulation, the mode competition between two modes for different combinations of the strength of the pump noise, the coupling constant and the difference of pump parameters have been investigated. The results show the following. (i) The pump noise dramatically affects the mode competition. (ii) The mode competition is quite sensitive to changing of the coupling constant near the line center. (iii) The mode competition gets stronger and stronger with increasing absolute value of the difference of pump parameters.

We investigate nonlinear dynamical systems from the mode competition point of view, and propose the necessary conditions for a system to be chaotic. We conjecture that a chaotic system has at least two competitive modes (CM's). For a general nonlinear dynamical system, we give a simple, dynamically motivated definition of mode suitable for this concept. Since for most chaotic systems it is difficult to obtain the form of a CM, we focus on the competition between the corresponding modulated frequency components of the CM's. Some direct applications result from the explicit form of the frequency functions. One application is to estimate parameter regimes which may lead to chaos. It is shown that chaos may be found by analyzing the frequency function of the CM's without applying a numerical integration scheme. Another application is to create new chaotic systems using custom-designed CM's. Several new chaotic systems are reported.

Tunable Lasers are key-components for Wavelength Division Multiplexing optical communication applications at 1.55μm. In this paper, we report the study of low to mid frequency noise power spectral densities and correlation factors in various spectral purity configurations, using the Bragg section tunability around a mode-hopping situation.