Implementation of a Phase Only Spatial Light Modulator as an Atmospheric Turbulence Simulator at 1550？nm

Modeling and simulating atmospheric turbulence in a controlled environment have been a focus of interest for scientists for decades. The development of new technologies allows scientists to perform this task in a more realistic and controlled environment and provides powerful tools for the study and better understanding of the propagation of light through a nonstatic medium such as the atmosphere. Free space laser communications (FSLC) and studies in light propagation through the atmosphere are areas which constantly benefit from breakthroughs in technology and in the development of realistic atmospheric turbulence simulators, in particular (Santiago et al. 2011). In this paper, we present the results from the implementation of a phase only spatial light modulator (SLM) as an atmospheric turbulence simulator for light propagation in the short-wave infrared (SWIR) regime. Specifically, we demonstrate its efficacy for its use in an FSLC system, at a wavelength of 1550？nm. 1. Introduction The atmosphere is a nonhomogeneous medium that has properties sensitive to changes in pressure, temperature, humidity, and wind speed and direction. Its layered nature and sensitivity to different variables generate turbulent fluctuations in the refractive index of the atmosphere. These turbulent fluctuations are considered to be the principal contributors of the phase fluctuations in traveling optical waves [1–4]. For decades, scientists have been studying and modeling atmospheric turbulence to obtain a better understanding of its properties and behavior. Atmospheric turbulence simulators (ATS) are powerful tools enabling researchers to evaluate and predict the performance of optical systems prior to field implementation. Some of the most common methods used to simulate atmospheric turbulence are rotating phase plates etched with phase screens, hot plates, or liquid crystal modulators. The use of hot plates is limited by the inability to accurately estimate or precisely control the degree of atmospheric turbulence introduced to the optical path. Rotating phase plates are extremely costly and limited by the number of phase screens. Recent improvements to Liquid Crystal-based Spatial Light Modulators (LCSLM) have made these types of modulators more useful as an ATS for system calibration and design [5–7]. This is because a given set of aberrations can be carefully introduced and controlled in a laboratory environment for both frozen phase screen studies and real-time turbulence emulations [8]. This paper describes the implementation of such an LCSLM in the short-wave