Low-threshold CW eye-safe vortex generation from an intracavity pump-wave off-axis pumped OPO

A low-threshold efficient setup for CW wavelength versatile vortex generation is proposed. The intracavity optical parametric oscillator is utilized for low-threshold operation. By using the pump-wave off-axis pumping for the signal-wave oscillator, high-order Hermite-Gaussian modes at the eye-safe region can be obtained, which can further generate a vortex via an astigmatism mode converter. The overall laser performance is additionally verified to be better by comparing it with the diode off-axis pumping method where the TEM_1,0 pump wave was generated first for the signal-wave TEM_1,0 mode oscillation. This method is expected to be further applied for more complicated structured light generation.