Vector characteristics of sub-ps 1.9 µm pulses produced by non-PM thulium-doped all-fiber MOPA

The efficiency of using 1.9 µm ultrashort pulses generated by thulium-doped all-fiber master oscillator power amplifiers (MOPAs) in various applications, such as material ablation, supercontinuum and Raman soliton generation, and other fields, depends not only on the amplitude-phase characteristics but also on the polarization state of the pulse. Despite the advantages of non-polarization-maintaining (non-PM) MOPAs, such as ease of assembly, low cost of fibers, and greater flexibility of parameters, the main disadvantages are sensitivity to external influences and the possibility of generating pulses with complex polarization. Thus, non-PM MOPAs have the potential to be used in laboratory settings, and tuning the pulse electric field vector parameters can improve their application efficiency. However, pulse electric field vector measurements have not been widely used in laser development research due to their complexity. Therefore, the objective of this study is to perform vector electric field measurements of sub-ps pulses at a wavelength of 1.9 µm generated by a non-PM thulium-doped all-fiber MOPA. This study presents vector measurements of the pulses at different polarization controller settings and average radiation power levels of the developed MOPA by using the tomographic ultrafast reconstruction of transverse light E-fields (TURTLE) principle, highlighting the importance of such measurements.