Switchable 3D optofluidic Y-branch waveguides tuned by Dean flows.

Area of Science:

• Optofluidics
• Photonics
• Microfluidics

Background:

• Optical branch waveguides are crucial for optical communication but lack tunability in solid-state devices.
• Existing liquid optical devices face signal leakage issues when liquid refractive index is lower than solid channels.
• Tunable liquid optical devices are highly desirable for advanced optical systems.

Purpose of the Study:

• To demonstrate a tunable three-dimensional (3D) optofluidic Y-branch waveguide.
• To overcome the limitations of 2D liquid waveguides and solid-state devices.
• To achieve reconfigurable light splitting with low signal loss.

Main Methods:

• Fabrication of 3D Y-branch waveguides within planar microchannels.
• Introduction of Dean flow to manipulate liquid optical properties.
• Adjustment of flow rates to control 3D Y-branch profiles and light splitting ratios.

Main Results:

• Demonstrated tunable light intensity splitting ratios from 0 to 1.
• Achieved low transmission loss of 0.97 dB at a 10° splitting angle.
• Showcased improved light confinement in 3D liquid structures compared to 2D counterparts.
• Enabled greater freedom in selecting liquid media independent of solid channel refractive index.

Conclusions:

• The developed 3D optofluidic Y-branch waveguide offers significant advantages in tunability and performance.
• The Dean flow-induced reconfiguration provides a novel method for controlling light splitting.
• These devices hold strong potential for integrated optofluidic applications and future optical communication systems.