Random Lasing via Plasmon-Induced Cavitation of Microbubbles.

Area of Science:

• Physics
• Materials Science
• Optics

Background:

• Random lasing is observed in plasmonic nanoparticle (NP) solutions.
• Current theories attribute this to optical cavities formed by NP local fields and scattering.
• An alternative mechanism is proposed that does not rely on plasmon resonance.

Purpose of the Study:

• To investigate an alternative mechanism for random lasing in plasmonic nanoparticle solutions.
• To explore the role of laser-induced microbubbles in optical feedback.
• To challenge the conventional understanding of random lasing in these systems.

Main Methods:

• High-speed confocal microspectroscopy was used to observe NP dynamics.
• Photophysical dynamics of NPs in solution were analyzed.
• Electromagnetic simulations were performed to model optical feedback mechanisms.

Main Results:

• Laser pulses induce microbubble formation around NPs.
• Observed sharp spectral peaks (<1.0 nm) match random lasing signatures.
• Simulations show microbubbles can form optical corrals with standing waves for feedback.

Conclusions:

• Plasmonic-induced microbubbles can generate optical feedback.
• This mechanism provides an alternative explanation for random lasing.
• Ensembles of microbubbles are sufficient to sustain coherent optical feedback.