That doesn't involve a laser like in the article, and is probably much slower. I don't think you can get Terahertz speeds by just using Newtonian physics on water.
While the paper's keywords list includes both microfluidics and photonics, nothing about the device is anything like an opto-fluidic logic gate. The laser is used to measure properties of cells suspended in the fluid, with the output light signal being processed by conventional photonics.