Generation of spectrally narrow, phase-stable pulse trains using a birefringent crystal array.

Area of Science:

• Optics and Photonics
• Ultrafast Laser Science

Background:

• Optical free-induction-decay (FID) signals are critical for high-resolution spectroscopy.
• Gating these signals typically requires complex and active systems.

Purpose of the Study:

• To develop a stable, passive method for generating stacked pulses for optical FID signal gating.
• To characterize the temporal and spectral properties of the generated stacked pulses.

Main Methods:

• Utilized a birefringent crystal array of five SiO2 plates with increasing thickness to generate a 32-subpulse train.
• Employed second-harmonic generation (SHG) to analyze spectral response.
• Performed cross-correlation frequency-resolved optical gating (XFROG) and numerical simulations for temporal characterization.

Main Results:

• Generated a phase-stable 32-subpulse train spanning approximately 1.3 ps.
• Observed a narrow SHG bandwidth (~0.37 nm FWHM), indicating suitability for long-duration gating.
• Achieved low side lobes and a low FROG error of 0.9% through XFROG and simulations.

Conclusions:

• The birefringent crystal array provides a robust and stable method for generating temporally extended fields.
• This technique presents a fully passive and stable alternative for gating in optical FID detection, advancing spectroscopic capabilities.