The numerical investigation of difference frequency generation in a system of two-wavelength semiconductor lasers with a vertical external resonator is presented. Maps of dynamic regimes on the plane of parameters “pump power - delay time in the external resonator" are constructed. The regions of continuous wave, periodic oscillations, as well as quasiperiodic and chaotic oscillations of the radiation intensity are distinguished. The existence of stable periodic motions of the system can be explained in terms of the concept of synchronizing the frequency of normal modes with the frequency of intermode beats.
We present a theoretical investigation of two longitudinal mode microelectromechanical system (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL). The spatio-temporal dynamics of semiconductor laser with particular focus on the parameters relevant for THz photomixing is studied. A four-level model which allows for the polarization of the laser field by including the spin sublevels of the conduction and valence bands of a semiconductor is introduced. The maximum obtained wavelength separation between modes is ~30 nm which corresponds to 3.77 THz in frequency range.
The numerical model for dynamics of long fiber ring Raman laser is proposed. The model is based on the transport equations and Courant-Isaacson-Rees numerical method. Different regimes of a long ring fiber Raman laser are investigated.
We study the dynamics of a neodymium-doped fiber laser coupled to ytterbium-doped fiber laser via nonlinear crystal which is placed inside the resonator. The transient signals may present different profiles depending on several conditions (degree of coupling between both lasers, pump powers of each one, resonator length, etc.) In particular, an appropriate choice of working conditions makes possible to suppress relaxation oscillations and to shorten the time elapsed since the moment of pump switch-on till steady state.
Gaussian pulse ansatzs were used in description of pump and Stokes pulse nonlinear interaction in optical fiber.
Modified generalized momenta method is used for derivation of the ordinary differential equations for pulse
parameters allowing the gain and saturation effects.
We propose a method of generation terahertz radiation based on difference frequency mixing of colliding femtosecond
pulses in the wavelength range 1550 nm. Obtaining a defined frequency difference is due to stimulated
Raman soliton generation via splitting of multisoliton replica pulses in a photonic-crystal fiber. Pulse train is
generated by a single laser. The results of numerical simulation of such process, based on the solution of the
modified nonlinear Schrödinger equation, which includes the impact of higher-order dispersion, the optical Kerr
effect and Raman amplification are presented. One of the easiest ways to generate pulses with a frequency
difference is to use the fibers with variable dispersion.
Numerical model of fiber laser is proposed suitable for numerical investigation of fiber laser dynamics. The
model is based on the equations describing propagation effects, linear coupling of oppositely running pulses and
its interaction in a ring or standing-wave fiber cavity. The derivation of these equations is based on the field
representation in terms of longitudinal harmonics rather than monochromatic waves. This allows to formulate
easily the initial values problem for numerical simulations, to the contrast to two-points boundary values problem
in the case of monochromatic wave decomposition. Numerical results are presented for the case of Raman pump
by CW monochromatic laser radiation using upwind method. The results can be applied for investigation of
dynamics in fiber lasers, including Raman lasers, especially with long cavities, and random feedback fiber lasers.
The application of microstructured fiber with periodically modulated diameter for a flat supercontinuum generation
is proposed. We report the results of numerical study of spectral broadening of low-order femtosecond
solitons. It is shown that periodical modulation of phase-matching conditions leads to spectrum broadening and
disappearing of spectral gap between spectra of soliton and dispersive wave. The shape of output spectrum
depends on period of the modulation of diameter of microstructured fiber.