Investigation of Polarization-Dependent Efficiency in Ultra-Broadband Mid-Infrared Pulse Generation via Two-Color Laser-Induced Filamentation

Yen Chen Ko^1*, Wei Hong Huang¹, Yi Ruei Sie¹, Yin Jun Liu², Chih Wei Luo^1,2,3

¹Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
²Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
³National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan

* Presenter:Yen Chen Ko, email:keyancheng.sc12@nycu.edu.tw

In this study, we investigated the generation efficiency of ultra-broadband coherent mid-infrared (MIR) pulses via laser-induced filamentation in a two-color field configuration. The fundamental light source was a regenerative amplifier laser at 800 nm, with 35 fs pulse duration, 4 mJ energy, and 1 kHz repetition rate. A type-I second harmonic generation (SHG) crystal was employed to produce 400 nm second harmonic pulses, which propagated non-collinearly with the 800 nm pulses. These pulses were focused using a dielectric concave mirror to induce filamentation, with independent polarization control of the two driving fields before their recombination. We demonstrate that the efficiency of MIR generation is significantly influenced by the polarization configuration of the two-color pulses. By systematically manipulating the polarization states, we observed notable variations in the MIR pulse efficiency, providing key insights into optimizing broadband pulse generation. These findings are crucial for developing efficient and tunable MIR sources, with potential applications in spectroscopy, materials science, and other fields requiring broadband infrared light.

Keywords: Mid-Infrared Generation, Laser-Induced Filamentation, Ultra-Broadband Pulses