Optoacoustic detection of nanosecond time scale photoinduced lensing effects in liquids

Article Acoustics

The role of electrostriction in the generation of acoustic waves by optical forces in water

N. G. C. Astrath et al.

Summary: We propose semi-analytical solutions that describe the spatial and temporal distributions of temperature and pressure inside low-absorbing dielectrics excited by tightly focused laser beams. These solutions are compared to experimental measurements in water, where variations in the local refractive index due to acoustic waves generated by electrostriction, heat deposition, and the Kerr effect at different temperatures are observed. The experimental results show excellent agreement with the modeling predictions, with electrostriction being the dominant transient effect in acoustic wave generation. Measurements at 4.0 degrees C demonstrate significant reduction in the thermoelastic contribution to the optical signal due to the low thermal expansion coefficient of water at this temperature.

PHOTOACOUSTICS (2023)

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Article Optics

Optical detection of the ultrasound-induced pulsed thermal lens close to the ice-water phase transition

G. A. S. Flizikowski et al.

Summary: Piezo-optic and thermo-optic coefficients are crucial material properties for the design and optimization of optical devices. Accurate measurement and control of these coefficients are necessary for achieving high performance and reliability. This article investigates these properties for water at low temperatures using the optical detection of the ultrasound-induced thermal lens effect. The results reveal the anomalous behavior of water around 4 degrees C, and the thermal lens method is employed to determine the temperature dependence of the coefficients.

APPLIED OPTICS (2023)

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Article Optics

Unveiling bulk and surface radiation forces in a dielectric liquid

N. G. C. Astrath et al.

Summary: Precise control over light-matter interactions is crucial for optical manipulation, material characterization, and nanotechnology applications. In this study, we use tightly focused pulsed laser beams to investigate the optical forces in a dielectric fluid and decouple the thermal and nonlinear effects from the radiation forces. Our findings reveal that the time-dependent pressure distribution within the fluid is mainly caused by electrostriction effects, shedding light on the long-standing controversy surrounding the basic definition of electromagnetic momentum density in matter.

LIGHT-SCIENCE & APPLICATIONS (2022)

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Article Physics, Applied

High-speed non-contact measurement of elasto-optic coefficient via laser-induced phonons

Jiarui Li et al.

Summary: This study proposes a high-speed non-contact method based on laser-induced phonons to measure the elasto-optic coefficients of common liquids. By deciphering Brillouin spectra, the elasto-optic coefficients and viscoelastic parameters can be obtained simultaneously. The introduction of the elasto-optic coefficient makes the characterization more sensitive, and this method can be potentially used for mechanical imaging and characterization of biological cells and tissues.

APPLIED PHYSICS LETTERS (2022)

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Review Optics