Intracavity vector vortex pattern generation in a diode-pumped Tm:Y₂O₃ ceramic laser with X-type folded resonator

This paper reports 2 μm intracavity vector vortex pattern generation in a diode-pumped isotropic Tm:Y₂O₃ ceramic laser with an X-folded cavity configuration. By employing off-axis non-collinear hybrid pumping technology and control of the aperture, it demonstrates the direct generation and switching of four distinct polarized vortex beams-linearly polarized, elliptically polarized, anti-radially polarized and anti-azimuthally polarized-with a central wavelength of ∼2050 nm and carrying orbital angular momentum (OAM) of ±1ℏ. The corresponding M² factors are measured between 2.03 and 2.3, while maintaining high stability (minimum RMS of 0.47%), high purity (maximum SNR of 16.7 dB), and typical output power up to 242 mW. Additionally, various vortex arrays with different numbers of vortices having OAM of ±1ℏ are generated, and their basis vector synthesis and orbital angular momentum are theoretically simulated and experimentally verified. To the best of our knowledge, this represents the first laser that directly generates vector vortex beams using isotropic ceramics at the 2 μm wavelength. As such, it establishes a paradigm for structured light field manipulation based on ceramic gain media in the mid-infrared spectral region.