Constant-Envelope Modulation of Ince-Gaussian Beams for High Bandwidth Underwater Wireless Optical Communications

Wireless communication through underwater environments has become an area of increased interest in recent years. The use of Laguerre-Gaussian beams for communication through turbid environments has been well explored. We propose and demonstrate a high data rate communication method using Ince-Gaussian (IG) beams. Using the second harmonic generation process, the IG beam can be generated and modulated at gigahertz speeds. By controlling the phase matching condition of the SHG process, the coefficients of the generated modes can be controlled. Modulating the data in the phase of the beam provides constant envelope modulation. One advantage of this communication architecture is that it is power scalable. Using a 32 Quadrature Amplitude Modulated (QAM) signal, a data rate of 25 Gbit/s on a single channel was achieved with a bit error rate of
$9.95 \times {10}^{ - 4}$
which is below the forward error correction limit.