Jianlang Li
Shanghai Institute of Optics and Fine Mechanics - CAS, China
Title: Recent development in vortex and LG 01-mode Ti: sapphire laser
Biography
Biography: Jianlang Li
Abstract
Statement of the Problem: The Laguerre- Gaussian (LG) beam is known as doughnut-shaped cross section and spiral phase wavefront. The exponential term exp(−imφ) in its amplitude expression grants an orbit angular momentum to the beam photon, and such the vortex beam on LG modes becomes valuable for numerous applications such as optical manipulation, super-resolution microscopy, quantum communication, gravitational-wave detection, etc. Presently Ti-doped sapphire laser is one of the most common types of solid-state laser, which can generate femtosecond pulses with high peak power up to terawatt or petawatt level and be used in the fields of plasma physics, ion acceleration, etc. A new and interesting line for this laser is to generate vortex laser emission, which would be undoubtedly much more valuable for various kinds of applications in fields like the strong-field laser physics, etc. Nevertheless, the concern on vortex Ti: sapphire laser is much inferior to those in Nd: YAG and Yb: YAG lasers.
Methodology & Theoretical Orientation: We fabricated several spot defect spatial filters (SDSFs) with different sizes (i.e. diameters), then inserted them into an ever-built Ti: sapphire laser. The SDSF was antireflection coated glass plate containing a laser-treated opaque region of a circular shape. By inserting the SDSF into the laser cavity, the effect of the sizes of SDSF on the transverse laser mode and laser power was analyzed.
Findings: The Ti: sapphire laser emitted vortex LG01 mode at proper size of SDSF and pump power. When applying a spot defect with 140-mm diameter, the power of vortex LG01 mode reached 135 mW and the slope efficiency of the laser was 17.7%.
Conclusion & Significance: In summary, this study reported the first vortex LG01-mode Ti: sapphire laser. By using SDSF as intracavity mode selector, we demonstrated a vortex Ti: sapphire laser that emitted 800-nm and LG01-mode vortex light. The next investigation will focus on the mode-locked operation of the vortex Ti: sapphire laser by applying intracavity spot defect for spatial filtering.