Undersea laser communication using polarization and wavelength modulation

We report a technique to increase the data rate of a free-space all-undersea laser communication link using polarization and wavelength modulation. Measurements were made at various background light levels to estimate the required power increase as a function of bits per pulse. Transmission measurements were made of laser light through a 2-m-long tube filled with a mixture of Maalox and water to simulate ocean-water conditions for several receiver field-of-view (FOV) angles. A degree of polarization greater than 98% was measured at FOVs up to 100 mrad at an attenuation of 14 extinction lengths.