High-power, continuous-wave, tunable mid-IR, higher-order vortex beam optical parametric oscillator.

Area of Science:

• Optics and Photonics
• Nonlinear Optics
• Laser Physics

Background:

• Optical vortices possess unique phase and polarization properties.
• Generating higher-order optical vortices (HOVs) in the mid-infrared (mid-IR) is challenging.
• Existing methods often face limitations in vortex order and tunability.

Purpose of the Study:

• To report a novel experimental scheme for generating continuous-wave (cw), high-power, HOVs tunable in the mid-IR.
• To demonstrate efficient direct vortex transfer from near-IR to mid-IR wavelengths.
• To overcome limitations of singly resonant optical parametric oscillators (SROs) in generating HOVs.

Main Methods:

• Utilized a two-crystal, singly resonant optical parametric oscillator (T-SRO) configuration.
• Pumped one crystal with a Gaussian beam and the other with optical vortices (orders lp=1-6).
• Exploited coherent energy coupling between resonant signals in the T-SRO.

Main Results:

• Successfully generated tunable mid-IR idler vortices (orders li=1-6) from 2276-3576 nm.
• Achieved a maximum output power of 6.8 W for li=1.
• Demonstrated a high near-IR to mid-IR vortex conversion efficiency of up to 27.2%.

Conclusions:

• The T-SRO scheme facilitates the transfer of pump vortices of any order to the idler wavelength without stringent threshold conditions.
• This generic scheme enables flexible generation of HOVs across various spectral ranges and timescales (cw to ultrafast).
• The findings open new avenues for applications requiring tailored optical vortex beams in the mid-IR spectrum.