Dye lasing in optically manipulated liquid aerosols.

Area of Science:

• Optics and Photonics
• Atmospheric Science
• Laser Physics

Background:

• Microdroplets can act as optical cavities supporting whispering gallery modes (WGMs).
• Dye-doped microdroplets have potential for lasing applications.
• Optical tweezers enable precise manipulation and study of individual microdroplets.

Purpose of the Study:

• To demonstrate and characterize dye lasing in airborne microdroplets.
• To investigate the tunability of lasing wavelengths based on droplet size.
• To explore potential applications in atmospheric sensing.

Main Methods:

• Airborne glycerol-water microdroplets (7.7–11.0 μm diameter) doped with rhodamine B were generated.
• Optical tweezers were used to trap individual microdroplets.
• A Q-switched green laser served as the pump source for stimulated emission.

Main Results:

• Nonlinear intensity dependence of droplet WGMs on pump laser fluence confirmed dye lasing.
• Lasing wavelengths were tunable between 600 and 630 nm by adjusting droplet size.
• Whispering gallery mode lasing was successfully achieved in airborne microdroplets.

Conclusions:

• Airborne dye-doped microdroplets can function as tunable laser cavities.
• The high sensitivity of stimulated emission in these microdroplet lasers can be exploited for sensing applications.
• This work opens avenues for novel atmospheric probing techniques.