How light absorption modifies the radiative force on a microparticle in optical tweezers

Area of Science:

• Physics
• Optics
• Nanotechnology

Background:

• Optical trapping utilizes light's reflection and refraction to confine small particles.
• Absorption of light is often overlooked in theoretical models of optical trapping.
• This phenomenon is significant when dealing with semi-transparent or light-absorbing particles.

Purpose of the Study:

• To generalize Ashkin's model for radiative force to include light absorption.
• To analyze the interplay of refraction, reflection, and absorption in optical trapping.
• To provide a predictive framework for optical trapping experiments involving absorbing particles.

Main Methods:

• Developed a generalized model for radiative force on spherical particles.
• Incorporated the contribution of light attenuation and absorption within the particle's bulk.
• Investigated the balance of optical forces across various parameters and particle sizes.

Main Results:

• The generalized model quantifies the impact of light absorption on optical trapping forces.
• Detailed analysis reveals the relative importance of refraction, reflection, and absorption.
• Findings highlight conditions under which absorption becomes a critical factor in trapping efficiency.

Conclusions:

• The proposed model enhances understanding of optical trapping for absorbing particles.
• It offers a method to predict the significance of absorption in experimental setups.
• This work is crucial for optimizing optical trapping techniques for a wider range of materials.