Controlled Generation of Wavelength-Tunable Higher Order Poincaré Sphere Beams From a Femtosecond Optical Parametric Oscillator

Abstract

Although higher order Poincaré (HOP) beams are attractive due to their unique advantages and various efforts have been made for the generation of HOP sphere beams, the current generation technologies suffer from both limited output power and narrow bandwidth, preventing further practical applications. In this paper, we report on a femtosecond optical parametric oscillator (OPO) which can deliver high average power, on-demand arbitrary HOP sphere beams tunable across a wide spectral range in the near-infrared. The desired beam mode can be achieved by manipulating the geometric phase inside the OPO cavity to map the polarization to orbital angular momentum (OAM). Pumped by a Gaussian beam from an Yb-fiber laser, the generalized vector vortex femtosecond signal beams with spectral coverage from 1367 to 1650 nm are obtained. The device can produce over 200 mW structured beam signal power cross the complete tuning range with as much as 377 mW at 1480 nm for 2 W of input pump power. The proposed configuration, which shows superiorities of high average output power, flexible wavelength tunability and complete mode controlling property, may have direct implications in applications such as quantum optics and material processing.