We present ab initio calculations of cross sections for projectile and target excitation occurring in the course of He He collisions using a three-active-electron semiclassical nonperturbative approach. Intermediate impact energies ra
A switchable dual-wavelength erbium-doped fiber (EDF) laser is proposed and demonstrated. The interference filter is achieved by employing a phase-shifted fiber Bragg grating (PSFBG) combined with Sagnac loop structure. By adjust-ing polarization controll
An ultra broad band polarizer that operates in the telecommunication wavelength band is proposed. This device, which consists of a single suspended germanium resonant grating layer, is designed using the inverse mathematical method and the rigorous vector
We demonstrate experimentally that mid-infrared quantum cascade lasers (QCLs) operating under external optical feedback exhibit extreme pulses. These events can be triggered by adding small amplitude periodic modulation, with the highest success rate for