Polarization pulse dynamics in ultrafast thulium fiber lasers and nonlinear mid-infrared photothermal imaging

Abstract: Thulium fiber lasers operating in the eye-safe wavelength region from 1.7 µm to 2.2 µm are attractive for applications in gas/environmental sensing, biomedical diagnosis and surgery and nonlinear conversion. Dual-output ultrafast lasers pave a promising pathway towards compact single sources for high precision metrology and dual comb spectroscopy. Based on vector soliton dynamics, a compact fiber laser with co-generated, orthogonally polarized interlaced pulses and coherent energy exchange will be discussed. Further, self-organized multiple pulsing operation and the generation of extreme events and chaotic transient states is demonstrated in turn-key, compact thulium fiber lasers.

The second part of this talk will focus on mid-infrared vibrational photothermal spectroscopy in the fingerprint region (at wavelengths of ~5μm and longer), which can reveal characteristic details about molecular compounds with high sensitivity and specificity. A novel nonlinear photothermal operating regime with characteristic spectral narrowing, bifurcation and strong enhancements will be presented as a new pathway for material characterization. This technique can offer sub-diffraction limited imaging resolution and can be applied to analyze phase transitions or secondary protein conformations in biomedical tissue.