Characterizations for the photothermal effect of Rhodamine 6G using white-light interferometry and windowed Fourier...

Area of Science:

• Optics and Photonics
• Photothermal Effects
• Light-Matter Interactions

Background:

• The photothermal phenomenon converts light energy into heat, influencing material refractive index.
• Distinguishing thermal effects from optical/electronic resonance is key for expanding light-matter interaction applications.
• Precise refractive index measurements are vital for various scientific and technological fields.

Purpose of the Study:

• To develop a method for separating optical and thermal effects in light-matter interactions.
• To precisely measure the refractive index of a Rhodamine 6G (Rh6G) ethanol solution.
• To investigate the photothermal effect in Rh6G solutions under external excitation.

Main Methods:

• Utilized white-light interferometry combined with windowed Fourier transform and peak-fitting methods.
• Performed static and dynamic measurements to analyze the photothermal effect.
• Modeled the relative refractive index using spectrally a Fano-like resonance term and a linear dependent thermal term.

Main Results:

• Achieved a refractive index sensitivity of approximately 10^-6 (RIU) in the visible range.
• Successfully separated optical and thermal effects in the Rh6G-ethanol solution.
• Quantified the optical effect as approximately 0.2 × 10^-3 of the thermal effect in the low-light regime.

Conclusions:

• The developed approach enables precise separation of optical and thermal effects.
• This method can be applied to various fields requiring precision measurements of refractive index or transmission phase.
• The findings contribute to a deeper understanding of light-matter interactions and photothermal phenomena.