Conical emission by four-photon parametric generation by using femtosecond laser pulses

Area of Science:

• Nonlinear Optics
• Laser Physics
• Condensed Matter Physics

Background:

• Ultrafast laser-matter interactions can lead to complex phenomena like conical emission.
• Understanding the underlying mechanisms is crucial for developing advanced optical technologies.
• Ethylene glycol is a common solvent with interesting nonlinear optical properties.

Purpose of the Study:

• To investigate the conical continuum Stokes and anti-Stokes emissions generated by ultrafast laser pulses in ethylene glycol.
• To model the angular characteristics of the anti-Stokes conical emission.
• To elucidate the physical mechanisms responsible for the observed emissions.

Main Methods:

• Propagation of intense 100-fs/620-nm ultrafast laser pulses through ethylene glycol.
• Observation and analysis of conical continuum Stokes and anti-Stokes emissions.
• Theoretical modeling of the anti-Stokes emission angle using class-II Raman and four-photon parametric generation theories.

Main Results:

• Conical continuum Stokes and anti-Stokes emissions were successfully observed.
• The angle of the anti-Stokes conical emission was found to be dependent on nonlinear effects.
• The experimental observations were well-modeled by considering Raman and four-photon parametric processes in a small-scale filament.

Conclusions:

• The study demonstrates the generation of conical emissions in ethylene glycol via ultrafast laser pulses.
• Class-II Raman and four-photon parametric generations are identified as key mechanisms governing the anti-Stokes emission.
• The findings contribute to the understanding of nonlinear light propagation and spectral broadening in liquids.