Atmospheric Effects on an Optical Laser Communication Between Space and Ground

Laser communication is an expanding topic of interest. A combination of increased computer processing and increasing average data file size, coupled with the commercialization and subsequent proliferation of space, together create a need for cost effective high bandwidth communication. While optical systems offer much greater data rates than traditional radio frequencies can provide, optical bands are more susceptible to environmental conditions than radio frequency. Atmospheric effects are substantial on an optical beam, turbulent flow, eddies, moisture and salinization content are all issues near ground level. These low altitude effects create optical aberrations in the near field, impacting beam shape, intensity and phase. Atmospheric scattering and absorption are issues in the far field having an impact throughout the beam path, which can reduce signal intensity. Refraction along the optical path can adversely impact aiming from source to receiver. Background or noise floor and jitter can also present degradation of the transmitted signal. All of these create aberration to the beam and are the product of the optical effects of fluids. In addition, the performance of the optical system mounted in the satellite can be affected by thermo-structural reactions to orbiting thermal and structural loads. Reaching the optimized blend of variables through laboratory and field testing is expensive and time consuming. This work seeks to demonstrate how computer simulation can accurately model the complex physics underlying both atmospheric aero-optic degradation as well as structural thermal optical performance (STOP) of the optical system onboard a satellite. High fidelity models are created of each physics. Once a model is created to include all contributing factors, a series of simulations are run, to create a predicted set of values. These values will be compared to other publicly available results to determine viability of the computer simulation.