Raman random laser in one-dimensional system

Abstract

The probability of occurrence of random cavities' resonance frequency in the Stokes bandwidth of the Raman active medium can cause Raman laser oscillation in the random structures. Due to the small bandwidth of Raman line shape, the probability of the simultaneous appearance of random cavity resonance frequencies in the cascade Stokes line shapes is small. As a result, the cascade Raman laser oscillation effects on the saturation behavior are negligible. The nonlinear transmission matrix method is employed to determine the statistical behavior of a Raman random laser. Our results showed that the statistical behavior depends on the position of the Stokes line shape relative to the center of the stopband and the edge of the passband of the corresponding nondisorder system.

Controllable single-mode random laser using stimulated Raman gain

“…The probability of the Raman random lasing, effects of disordered parameter on it, spatial power distribution, light localization, and the threshold pump power were thoroughly studied by calculating the statistical behavior, and results were in agreement with experimental results [29]. In the present study, using this method, we demonstrated numerically the possibility of selecting any desired modes out of the available quasi-modes (QMs).…”

“…In the present study, using this method, we demonstrated numerically the possibility of selecting any desired modes out of the available quasi-modes (QMs). Our method is based on the TMM as well as solving the differential equations of Raman Stokes amplification [29]. The TMM is a frequency domain method that is widely used for study of the random lasing [5,6,11,15,16].…”

“…Compared to the finite-difference time-domain (FDTD) method [30], the advantages of the TMM method is that it can calculate the QMs with short lifetimes [11] and decrease the calculation volume; however, it leads to the same results as the FDTD method [16]. The transfer matrix of the 1D Raman random system is a nonlinear 2 × 2 matrix (M) that is determined by the boundary conditions, phase difference, and gain or loss of the medium [29]. Gain of the Raman medium can be obtained by solving the coupled differential equation for the pump and the Stokes power.…”

“…P p 0). The QMs correspond to the zero input fields that give m 11 0 [29]. The transmission spectrum is shown in Fig.…”

“…For the random systems in the overcoupling regime, the QMs are separated spectrally and easily identified for all simulations [11]. The number and the shape of the QMs are related to the parameters of the random system [29]. Moreover, the QMs' density in spectral domain varies according to its position in the passband or the stopband of the corresponding periodic sample [29].…”