Red Random Laser Based on Thermocavitation : Synthesis and Characterization.

Area of Science:

• Laser Physics
• Nanomaterials Science
• Fluid Dynamics

Background:

• Self-phase modulation (SPM) is a nonlinear optical phenomenon.
• Thermal blooming (TB) follows SPM as a fluid heats and deforms under laser irradiation.
• Nanoparticles can alter thermal and optical properties of fluids.

Purpose of the Study:

• To investigate thermal blooming phenomena in dye solutions with various nanoparticles.
• To analyze the effect of nanoparticles on thermocavitation and bubble formation.
• To study the influence of thermal cavitation on random laser actions.

Main Methods:

• Utilized a continuous-wave (CW) laser at 405 nm with 100 mW optical power.
• Focused the laser beam onto a quartz cuvette containing dye solution with Ag NWs, Fe₂O₃, and AgNWs: Fe₂O₃ nanoparticles.
• Observed far-field diffraction patterns and characterized random laser actions.

Main Results:

• Observed a shift from self-phase modulation (SPM) loops to a distinct diffraction pattern indicating thermal blooming (TB).
• Demonstrated that nanoparticles (Ag NWs, Fe₂O₃) affect the speed and number of bubble formations during thermocavitation.
• Noted random laser actions in both the presence and absence of thermal cavitation.
• Found that thermal cavities significantly impact pump threshold, spectral linewidth, and emission intensity.

Conclusions:

• Thermal blooming is a distinct phase following SPM, influenced by nanoparticle-induced thermocavitation.
• Nanoparticles play a crucial role in modulating thermocavitation dynamics and random laser emission.
• The presence of a thermal cavity significantly alters the characteristics of laser emission spectra.