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

TL;DR

This paper introduces a novel continuous-wave optical parametric oscillator that efficiently generates high-power, tunable mid-IR vortex beams of various orders, enabling broad wavelength coverage and high conversion efficiency.

Contribution

The work demonstrates direct transfer of optical vortices from near-IR to mid-IR in a cw T-SRO setup, overcoming previous order restrictions and achieving high power and efficiency.

Findings

Idler vortices tunable from 2276-3576 nm

Maximum output power of 6.8 W at order li=1

Conversion efficiency up to 27.2%

Abstract

We report on a novel experimental scheme to generate continuous-wave (cw), high power, and higher-order optical vortices tunable across mid-IR wavelength range. Using cw, two-crystal, singly resonant optical parametric oscillator (T-SRO) and pumping one of the crystals with Gaussian beam and the other crystal with optical vortices of orders, lp = 1 to 6, we have directly transferred the vortices at near-IR to the mid-IR wavelength range. The idler vortices of orders, li = 1 to 6, are tunable across 2276-3576 nm with a maximum output power of 6.8 W at order of, li = 1, for the pump power of 25 W corresponding to a near-IR vortex to mid-IR vortex conversion efficiency as high as 27.2%. Unlike the SROs generating optical vortices restricted to lower orders due to the elevated operation threshold with pump vortex orders, here, the coherent energy coupling between the resonant signals of the crystals of T-SRO facilitates the transfer of pump vortex of any order to the idler wavelength without stringent operation threshold condition. The generic experimental scheme can be used in any wavelength range across the electromagnetic spectrum and in all time scales from cw to ultrafast regime.