Thermally induced laser pulsing to measure weak optical absorptions

Area of Science:

• Laser Physics
• Spectroscopy
• Physical Chemistry

Background:

• Continuous-wave (cw) dye lasers typically operate in a continuous mode.
• Pulsed laser operation is often desirable for specific spectroscopic applications.
• Thermal lensing is a phenomenon where laser-induced heating alters the refractive index of a medium.

Purpose of the Study:

• To demonstrate the conversion of a cw dye laser to pulsed operation using intracavity thermal lensing.
• To establish the pulse width as a quantitative measure of solution absorptivity.
• To present experimental data for measuring solvent absorptivity and solute concentration.

Main Methods:

• Utilized intracavity thermal lensing to induce pulsed operation in a cw dye laser.
• Correlated the laser pulse width with the absorptivity of solutions placed within the laser cavity.
• Experimentally determined the absorptivity of various pure solvents and quantified solute concentrations.

Main Results:

• Successfully converted cw dye laser operation to pulsed mode via thermal lensing.
• Established a direct relationship between pulse width and solution absorptivity.
• Quantified the base e absorptivities for water, methanol, acetone, and carbon tetrachloride.
• Achieved a minimum detectable absorptivity of approximately 4 x 10(-6) cm(-1) for CCl(4) in a 10-cm cell.

Conclusions:

• Intracavity thermal lensing is an effective technique for achieving pulsed laser operation from cw dye lasers.
• The developed method provides a sensitive approach for measuring solution absorptivity and determining solute concentrations.
• The technique offers potential for precise quantitative analysis in various chemical and physical measurements.