High-sensitive absorption measurement in transparent isotropic dielectrics with time-resolved photothermal...

Area of Science:

• Optics and Photonics
• Materials Science
• Laser Physics

Background:

• Accurate absorption measurement is crucial for understanding light-matter interactions in optical materials and gases.
• Existing methods often struggle with low absorption levels, fast dynamics, or precise calibration.

Purpose of the Study:

• To introduce a novel time-resolved photothermal common-path interferometry scheme for precise absorption measurements.
• To calibrate the scheme using a developed theory of diffraction on deformations.
• To investigate absorption in Suprasil 311 silica glass and atmospheric air, including nonlinear effects.

Main Methods:

• Implementation of a time-resolved photothermal common-path interferometry setup with fast heating and minimal heat diffusion.
• Development of a calibration theory considering diffraction on deformations and stresses in inhomogeneous temperature fields.
• Measurement of absorption in Suprasil 311 silica glass and laboratory air at 1071 nm with high signal-to-noise ratio.

Main Results:

• Successful measurement of low absorption coefficients in Suprasil 311 silica glass (2.8·10⁻⁶ cm⁻¹) and air (2.9·10⁻⁸ cm⁻¹).
• Distinguished contributions of Kerr and striction nonlinearities to absorption in silica glass, observing the time evolution of strictional deformations.
• Observed anomalous temporal absorption development in atmospheric air for broadband laser radiation.

Conclusions:

• The developed photothermal interferometry scheme offers high sensitivity and time resolution for absorption measurements.
• The method allows for the study of nonlinear optical phenomena and dynamic processes in materials and gases.
• New insights into the absorption characteristics of silica glass and atmospheric air were obtained.