Improving the Hufnagel-Andrews-Phillips refractive index structure parameter model using turbulent intensity.

This paper proposes a modification of the Hufnagel-Andrews-Phillips (HAP) Refractive Index Structure Parameter model that will better characterize the HAP profile against experimental data using the turbulent intensity, which is the ratio of wind speed variance to the average wind speed-squared, and Korean Refractive Index Parameter yearly statistics, Comparisons between this modified HAP model, the Critical Laser Enhancing Atmospheric Research 1 (CLEAR 1) profile model and several of the data sets are made. These comparisons highlight that this new model offers a more consistent representation of the averaged experimental data profiles than the CLEAR 1 model did. In addition, comparisons between this model and various experimental data set reported in the literature will show good agreement between the model and averaged data, and reasonable agreement with non-averaged data sets.

Probability density function estimation for filament creation in lossy, turbulent, nonlinear media.

Optical Kerr effects induced by the propagation of high peak-power laser beams through real atmospheres have been a topic of interest to the nonlinear optics community for several decades. Previous work has focused on estimating the Filamentation Onset Distance (FOD) in real atmospheres but not its statistical variance. This paper describes two ad hoc engineering models for predicting the FOD Probability Density Function (PDF) for lossy, turbulent, nonlinear media.

Optical Kerr effect field measurements and ad hoc engineering model comparisons.

Optical Kerr effects induced by the propagation of high peak-power laser beams through real atmospheres have been a topic of interest to the nonlinear optics community for several decades. This paper proposes a new analytical model for predicting the filamentation/light channel onset distance in real atmospheres based on modulation instability model considerations. The normalized intensity increases exponentially as the beam propagates through the medium.

Adaptive optics model characterizing turbulence mitigation for free space optical communications link budgets.

Free-space optical communications (FSOC) is becoming an important option for both atmospheric and space-based high data rate networks. Long-range, mobile FSOC links in the former environments must mitigate the effects of turbulence if they are to provide reliable, high link availability under cloud-free atmospheric conditions. Adaptive optics (AO) has been proposed as one means of reducing link degradation in turbulence, but field validated AO performance models are few and not definitive.

Engineering equations for the filamentation collapse distance in lossy, turbulent, nonlinear media.

The propagation of high peak-power laser beams in real atmospheres has been an active research area for a couple of decades. Atmospheric turbulence and loss will induce decreases in the filamentation self-focusing collapse distance as the refractive index structure parameter and volume extinction coefficient, respectively, increase. This paper provides a validated analytical method for predicting the filamentation onset distance in lossy, turbulent, nonlinear media.

Engineering equation for filamentation self-focusing collapse distance in atmospheric turbulence.

The propagation of high peak-power laser beams in real atmospheres will be affected by both linear and nonlinear effects contained therein. Atmospheric turbulence usually will induce decreases in the filamentation self-focusing collapse distance for refractive index structure parameter increases. This paper provided the first validated analytical equation for predicting the nonlinear self-focusing collapse distance based on a modification of Petrishchev's and Marburger's theories.

Engineering equations for characterizing nonlinear laser intensity propagation in air with loss: erratum.

We present an erratum regarding the x-axis label in several figures, and one equation citation correction.

Engineering equations for characterizing non-linear laser intensity propagation in air with loss.

The propagation of high peak-power laser beams in real atmospheres will be affected at long range by both linear and nonlinear effects contained therein. Arguably, J. H.

Statistical detection of resolved targets in background clutter using optical/infrared imagery.

The use of optics to detect targets has been around for a long time. Early attempts at automatic target detection assumed target plus noise, which means that the targets were small compared to the pixel field of view and therefore unresolved. However, the advent of advanced focal plane technology has resulted in optical systems that can provide highly resolved target images.

High-sensitivity DPSK receiver for high-bandwidth free-space optical communication links.

A high-sensitivity modem and high-dynamic range optical automatic gain controller (OAGC) have been developed to provide maximum link margin and to overcome the dynamic nature of free-space optical links. A sensitivity of -48.9 dBm (10 photons per bit) at 10 Gbps was achieved employing a return-to-zero differential phase shift keying based modem and a commercial Reed-Solomon forward error correction system.

Free-space optical communications link budget estimation.

This paper describes a new methodology of estimating free-space optical communications link budgets to be expected in conditions of severe turbulence. The approach is derived from observing that the ability of an adaptive optics (AO) system to compensate turbulence along a path is limited by the transmitter and receiver Rayleigh range, proportional to the diameter of the optics squared and inverse of the wavelength of light utilized. The method uses the Fried parameter computed over the range outside of the transmitter and receiver Rayleigh ranges, to calculate the Strehl ratios that yield a reasonable prediction of the light impinging on the receiving telescope aperture and the power coupling into the fiber.