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.
The present study demonstrates numerically a novel approach to perform a controllable single-mode random laser, using stimulated Raman gain. Due to the narrow linewidth of the Raman line shape, only one of the modes of the passive random system can lase. The robust control on the emission spectrum was achieved through the selection of any desired quasi-modes, by adjusting the pump wavelength in order to place the center of Raman line shape on desired quasi-modes. This approach was proved using a developed nonlinear transfer matrix method for a 1D Raman random system. The proposed method includes the Raman gain saturation and the frequency-dependent index of refraction.
In this paper, a periodic structure of different dielectric layers is proposed and investigated for relativistic electron acceleration. The periodic dielectric structure provides an accelerating electric field inside the structure. Results show that the electron beam can experience a strong electric force in one direction during propagation in the structure, leading to the acceleration gradient increasing by more than double in comparison with dual-grating structures. Acceleration gradient enhancement occurs without increasing the electric field much inside the structure; therefore, the maximum achievable acceleration gradient and acceleration factor are increased by more than 100%, reaching 0.7. Thereby, by using the proposed structure GV/m, the acceleration gradient can be achieved with a wide electron channel. Also, the required input laser fluence is reduced for the same acceleration gradient. Acceleration gradient and acceleration factor optimization is done corresponding to structure parameters. Our work shows that the proposed structure helps to make dielectric laser accelerators more efficient.
In this paper, two-axis dielectric laser acceleration is proposed by introducing a dual-grating base laser accelerator structure excited with two orthogonal propagating ultrashort laser pulses. A 2D periodic structure is designed that provides phase synchronicity between the relativistic particle beam and orthogonal propagating laser pulses. In this way, the particle beam can gain energy from both laser pulses simultaneously. It is numerically demonstrated that utilizing this method increases both the acceleration gradient and acceleration factor up to 90% in comparison with dual-grating dielectric laser acceleration. Also, deflecting force elimination, particle beam quality, and bunch acceleration efficiency can be improved using this method.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.