超聲波在水下光導之探討 Underwater Light Waveguide with Acoustic Vortex Structure
This research project aims to a curved waveguide structure under water using only ultrasound. As the pressure and energy emitted from the ultrasound transducer causes cavitation in water, we can create any structure or arrangement of microbubbles through controlling the distribution of energy. By creating a ring shaped, hollow structure of microbubbles and utilizing the difference between the refractive index of the two materials, we can trap a beam of light within the structure as the beam undergoes total internal reflection, and therefore creating a waveguide structure like those of an optic fiber.
As the wave packet of an Airy Beam follows a curved path, adjusting the phase of each element on the transducer base on the Airy Function could give us a field where the energy is concentrated on said curved path. Combining this with a Vortex structure, which offsets the energy to the sides and creates a center with 75% less energy, we created a curved waveguide structure with a curvature of approximately 3 degrees. ‘
With the FOCUS system we can obtain the precise and relative intensity of energy, further showing where or how microbubbles are arranged, Furthermore, with a ray tracing program, we can input the tube pathway created with microbubbles in the form of function, achieving a precise result. We would then go on and test simulations with a physical transducer and hydrophone, verifying that our theory works and a curved waveguide is achieved.