Description

The bandwidth of optical free-space underwater communication channels typically is reduced in turbid environments by temporal and spatial dispersion of the modulated signal. Light propagation through a highly scattering medium such as natural water is strongly affected by interaction with particles; the nature and amplitude of this effect is generally described by the inherent optical properties of the propagation medium. As for optically thinner (i.e., less turbid) media, photons might arrive at the detector without having encountered scatterers (i.e., ballistic photons), or perhaps have scattered only once (i.e., single-scattering), whereas for optically thicker media, photons arriving at the detector might have encountered numerous scattering events (i.e., snake photons). These photons contribute to temporal dispersion (i.e., pulse stretching), and they carry scattering information from an ensemble of particles.

This work involves studying the effect of higher order forward scattering on one-way channel characteristics. To better understand this phenomenon, the full 16-element Mueller Matrix impulse response of the propagation medium was measured using several different scattering agents and turbidities. By studying the temporal structure of the depolarization of short pulses, the feasibility of more advanced polarization discrimination or diversity schemes is being examined.

For more information, please contact Anni Vuorenkoski Dalgleish

References

Vuorenkoski, A.K., Dalgleish, F.R., Giddings, T.E. and Shirron, J.J. Multi-path effects on optical communication links. Proc. ONR/NASA Ocean Optics XX. Sept 27th-Oct 1st 2010. Anchorage, AK

Dalgleish, F.R., Caimi, F., Vuorenkoski, A., Britton, W., Ramos, B., Giddings, T.E., Shirron, J.J. and Mazel, C.H. Efficient laser pulse time dispersion codes for turbid undersea imaging and communications applications. SPIE Defense, Security and Sensing Symposium. Orlando, FL, April 2010. Paper 7678-19 Invited Paper.