Wavelength-tunable Tm:Y₂O₃ ceramic vortex laser with a changeable orbital angular momentum state

Area of Science:

• Laser Physics
• Optical Communications
• Structured Light

Background:

• Orbital Angular Momentum (OAM) lasers offer potential for high-capacity optical communication by enabling OAM mode-division multiplexing (OAM-MDM).
• Integrating OAM with wavelength division multiplexing (WDM) requires tunable OAM light sources.

Purpose of the Study:

• To demonstrate a wavelength-tunable thulium-bulk (Tm-bulk) laser capable of controlling orbital angular momentum (OAM) states.
• To investigate the generation and properties of OAM states in the 2-µm spectral range.

Main Methods:

• Theoretical determination of Laguerre-Gaussian (LG0,n) mode excitation conditions based on annular pump beam propagation.
• Experimental generation of OAM states (|ħ| and |2ħ|) using a Tm:Y2O3 ceramic laser.
• Wavelength tuning achieved using a Lyot filter (LF).

Main Results:

• Successful generation of wavelength-tunable OAM states (|ħ| and |2ħ|) in the 2-µm range.
• Demonstration that spatial properties of scalar optical vortices are conserved during wavelength tuning.
• Confirmation of the feasibility of producing robust and compact wavelength-tunable structured light sources.

Conclusions:

• The developed Tm-bulk laser provides a novel source for wavelength-tunable structured light with controllable OAM.
• This technology holds significant promise for advancing optical communications, quantum optics, and super-resolution microscopy.