Complete optical analysis of an UV laser dye using saturation techniques

Area of Science:

• Photophysics and Laser Dyes
• Organic Photochemistry
• Spectroscopy

Background:

• Understanding laser dye performance is crucial for efficient laser operation.
• 3,5,3,5-tetra-t-butyl-p-sexiphenyl (TBS) is a UV laser dye with potential applications.
• Characterizing saturation properties and degradation pathways is essential for practical use.

Purpose of the Study:

• To investigate the saturation properties of the UV laser dye TBS when pumped by a XeCl laser.
• To determine the optical constants of TBS singlet states.
• To analyze the photochemical degradation of TBS at longer wavelengths.

Main Methods:

• Experimental measurements of optical saturation of transmission and amplifier gain.
• Fitting experimental data to photon propagation differential equations.
• Spectroscopic analysis including absorption and fluorescence spectra, and fluorescence lifetime measurements.

Main Results:

• Determined saturation intensities for absorption and emission, and optical constants of TBS singlet states.
• Measured excited-state absorption cross sections, quantum yield, and stimulated emission cross section.
• Identified two-photon excited state transitions leading to photochemical degradation, increasing with wavelength.

Conclusions:

• The saturation analysis method provides rapid and accurate evaluation of laser dyes.
• Photochemical degradation is a significant factor limiting TBS performance at longer wavelengths.
• Complete optical characterization of TBS singlet states was achieved.