Multi-level sorting of nanoparticles on multi-step optical waveguide splitter.

Area of Science:

• Optofluidics
• Nanoparticle sorting
• Integrated photonics

Background:

• Accurate nanoparticle size-based separation is crucial for various applications.
• Existing sorting methods often face challenges in throughput and scalability.

Purpose of the Study:

• To propose and demonstrate a novel optofluidic sorting method for size-dependent nanoparticle separation.
• To design a multi-level sorting unit using cascaded optical waveguide splitters.

Main Methods:

• Utilizing directional couplers (DCs) where power splitting ratios dictate trapping forces and potential wells.
• Particle size influences potential well distribution, guiding larger particles to specific waveguides.
• Employing particle-tracking analysis to validate sorting efficiency against potential well distributions.

Main Results:

• Demonstrated a four-level sorting unit capable of separating nanoparticles with critical sizes of 600nm, 700nm, and 800nm.
• Potential well distributions were shown to be dependent on particle size, enabling size-selective trapping.
• Statistical analysis of nanoparticle distribution, considering Brownian motion, aligned with theoretical potential well predictions.

Conclusions:

• The proposed optofluidic sorting method offers advantages like single wavelength excitation, low loss, and ease of fabrication.
• This design facilitates high-throughput, large-scale automatic nanoparticle sorting within integrated photonic circuits.
• The method holds significant potential for advanced lab-on-a-chip systems requiring precise particle manipulation.