Planar second-harmonic generation with noncollinear pumps in disordered media.

Area of Science:

• Nonlinear optics
• Solid-state physics
• Quantum optics

Background:

• Second harmonic generation (SHG) is a key nonlinear optical process.
• Disordered ferroelectric domain structures in quadratic nonlinear crystals present unique optical properties.
• Characterizing ultrashort laser pulses is crucial for many scientific applications.

Purpose of the Study:

• To experimentally investigate second harmonic generation (SHG) from two noncollinear beams in quadratic nonlinear crystals with disordered ferroelectric domain structures.
• To demonstrate the application of this SHG process for the characterization of femtosecond laser pulses.
• To develop a method for estimating femtosecond pulse parameters like pulse width, chirp, and front tilt.

Main Methods:

• Experimental study of second harmonic generation (SHG) using two noncollinear beams.
• Utilizing quadratic nonlinear crystals with disordered ferroelectric domain structures.
• Monitoring the evolution of the autocorrelation trace within the nonlinear crystal.

Main Results:

• Second-harmonic radiation is emitted in two cones and a plane, corresponding to the cross-correlation of fundamental pulses.
• The developed parametric process enables the estimation of femtosecond pulse width.
• Chirp and front tilt of femtosecond pulses can also be determined from the SHG signal.

Conclusions:

• The study successfully demonstrates a novel method for femtosecond pulse characterization using SHG in disordered nonlinear crystals.
• This technique offers a practical approach for real-time pulse parameter estimation.
• The findings contribute to advancements in ultrafast optics and laser diagnostics.