Modulate the laser phase to improve the ns-LIBS spectrum signal based on orbital angular momentum

Area of Science:

• Laser-induced breakdown spectroscopy (LIBS)
• Laser physics
• Plasma diagnostics

Background:

• Nanosecond laser-induced breakdown spectroscopy (ns-LIBS) is a powerful analytical technique.
• Enhancing the ns-LIBS signal intensity and stability is crucial for improved detection limits and accuracy.
• Traditional Gaussian beams may not provide optimal laser-matter interaction for plasma generation.

Purpose of the Study:

• To enhance the ns-LIBS signal by modulating laser phase using orbital angular momentum.
• To investigate the effect of vortex beams on laser ablation and plasma characteristics.
• To evaluate the improvement in spectral intensities and signal-to-background ratio (SBR) for metallic and non-metallic samples.

Main Methods:

• Modulating the laser phase of a Gaussian beam into a vortex beam using orbital angular momentum.
• Comparing the ablation characteristics and plasma properties generated by vortex and Gaussian beams under identical laser energy.
• Analyzing the spectral line intensities, SBR, plasma duration, and relative standard deviation (RSD) of the ns-LIBS signal.

Main Results:

• Vortex beams resulted in more uniform ablation and greater ablation mass compared to Gaussian beams.
• Peak intensities of Cu spectral lines increased by up to 1.26 times, and SBR by 1.25 times.
• Peak intensities of Si atomic spectral lines were enhanced by 1.58-1.94 times.
• Plasma induced by vortex beams showed prolonged duration, longer continuous background, and reduced RSD.

Conclusions:

• Phase modulation of laser beams via orbital angular momentum is an effective method for enhancing ns-LIBS signals.
• Vortex beams improve plasma properties, leading to significant signal enhancement for both metallic and non-metallic materials.
• This technique offers a promising approach for advancing the sensitivity and reliability of ns-LIBS analysis.