The Output Characteristics Of Near-infrared 1.3-3 μm Optical Vortex Parametric Oscillator Based On MgO:PPL

Near-infrared lasers in the wavelength range of 1-3μm are of interest in many fields,particularly,near infrared 1.3-3μm vortex laser sources are useful in many applications due to its unique optical properties.Optical parametric oscillator（OPO）technology is an effective way to achieve the near-infrared continuous tunable lasers.Wide range of wavelength tunability and large non-linear coefficient of the Quasi-phase matching crystals widely used in non-linear frequency conversion.In this research,investigated a quasi-phase-matched Mg O-doped periodically poled lithium niobate（Mg O:PPLN）linear cavity single-resonant optical parametric oscillator.Wavelength tunabilty of the system achieve by controlling the temperature and period of the crystal.The main content of this article is:（1）We demonstrated a single-resonant optical parametric oscillator（OPO）formed of a Mg O-doped periodically poled Li Nb O₃（Mg O:PPLN）crystal pumped with a 1.064μm nanosecond laser.When the periodic polarization period of the Mg O:PPLN crystal is 31μm,the wavelength tuning range of the signal is 1.661-2.057μm and the idler wavelength tuning range is 2.247-2.958μm through temperature tuning.When the pump energy is 20 m J,the highest energy is 1.786 m J of signal and 1.814 m J of idler output,corresponding to a total conversion efficiency of 18%.（2）We generated a tuneable（2.3–3μm）optical vortex output with an order of 1or 2 from a 1μm optical-vortex-pumped singly resonant parametric oscillator based on a Mg doped periodically poled lithium niobate crystal.The orbital angular momentum（OAM）from the pump vortex beam was transferred to the idler output in this signal singly resonant high-Q cavity configuration.A maximum vortex output energy of 1.52m J was achieved across a wavelength tuning range of 2.27–2.96μm.The signal beam in the Gaussian intensity distribution was also imaged across a 1.66–2μm tuning range.The wide spectral bandwidth was experimentally measured near the wavelength degeneracy and theoretically explained by group velocity mismatch and group velocity dispersion.