Optimizing ultrashort pulse in fiber laser based on artificial intelligence algorithm.

Ultrashort pulses, characterized by their short pulse duration, diverse spectral content, and high peak power, are widely used in fields including laser processing, optical storage, biomedical sciences, and laser imaging. The complex, highly-nonlinear process of ultrashort pulse evolution within fiber lasers is influenced by numerous aspects such as dispersion, loss, gain, and nonlinear effects. Traditionally, the split-step Fourier transforms method is employed for simulating ultrashort pulses in fiber lasers, which involves traversing multiple parameters within the fiber to attain the pulse's optimal state.

Controllable switch of a transmittance signal via polarization combination manipulation.

We propose and experimentally demonstrate a process in which we can control the behavior of an atomic medium to switch on or off transmittance signals at multiple frequencies in ladder-type electromagnetically induced transparency (EIT) of 5S-5P-5D transition of Rb87 atoms. By adjusting the polarizations of the applied optical fields, the amplitudes of the transmittance spectra at multiple frequency channels can be controlled. This mechanism originates from the competition between EIT subsystems and single-photon absorption with a contribution from different transition strengths.