Detection of objects inside water exploiting the Brillouin precursors

In a dispersive medium, the appearance of the steady-state part of the signal is preceded by oscillations known as precursors. This is due to the interrelated effects of phase dispersion and frequency dependent attenuation. The propagation properties of the precursors are different from the steady-state part of the pulse which makes them suitable for many applications. An example of these interesting properties is the non-exponential attenuation rate of the Brillouin precursor inside a Debye medium. Exploiting this property, it is suggested that an input pulse consisting of two mutually delayed Brillouin precursors would be a ldquonear optimalrdquo excitation in terms of the attenuation inside triply distilled water. Evidently, this optimized pulse is promising for remote sensing applications, aimed at detecting objects inside lossy dispersive media such as moist soil and water. In such cases, the optimized pulse can overcome the high loss of the medium and contribute to the detection of objects further inside the dispersive medium. In this paper, Finite-Difference Time-Domain (FDTD) simulations are employed to evaluate the usefulness of the optimized pulse for remote sensing applications, by modeling its scattering from objects inside water.