Researchers have developed a thulium-doped fiber laser source that produces ultrashort (sub-picosecond) vector pulses at a wavelength of 1.9 µm. This advance is significant because it combines the generation of ultrashort pulses with the ability to control their vectorial characteristics, such as polarization, in an all-fiber, non-polarization-maintaining (non-PM) integrated configuration.

The technique employs a thulium-doped fiber oscillator operating in the fiber lens mode-locking regime, followed by a fiber power amplifier (MOPA). The key lies in manipulating polarization states within the non-polarization-maintaining fiber, which allows for the generation of pulses with well-defined and controllable linear, circular, or elliptical polarization. The 1.9 µm wavelength is of particular interest for applications in medicine, spectroscopy, and communications.

This development represents a step forward in fiber laser engineering, offering a robust and compact platform for generating temporally and spatially structured light. The ability to produce ultrashort vector pulses with high quality and stability opens new avenues for experiments in nonlinear physics, material processing, and biological applications that require precise control over beam properties.