Enhanced backwards N2+ air-lasing for standoff spectroscopy

Air-Lasing is a promising candidate for standoff-spectroscopy that selectively amplifies spectral signatures to offer large directionality and signal to noise ratio. Demonstrations of air-lasing in femtosecond laser induced filaments opened new research efforts towards understanding air-lasing and its remote plasma generation capabilities. In this work we explore methods for optimizing the backwards lasing of N2+ ions using different polarization shaping schemes, second harmonic seeding, and vortex beams. The experimental results help us understand the mechanisms of backwards gain in air-lasing.