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Characteristics of C2µ derived from ultrasonic anemometer in an urban boundary layer

Al-Jiboori Monim H., Jaber Sundus H.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

2019

Vol. 28, No. 1

14--24

Fast-response observations of three components of wind and air temperature have been applied to calculate the refractive index function coefficient (C2µ ), which is needed to describe optical wave propagation in a turbulent medium. These were measured by 3D ultrasonic anemometer installed on the roof of the building of Atmospheric Science Department which is 19 m above ground level. Refractive index function coefficient was calculated for various periods of three seasons: winter, spring and summer.Diurnal variations of (C2µ) have been made at the surface layer for these seasons. The results show that high values ofmean (C2µ) occurred during the day time more than at night, also they occurred more in summer than in winter and spring. The results of (Cµ2) found to change with atmospheric stability, whereas they inversely decrease under unstable conditions, approximately constant at neutral cases, and increase under stable conditions. Values of (C2µ) on average appears to be lower during the rainy and foggy weather cases compared to those of clear sky.

ATLAS simulation of a laser diode for free space optical communication (FSOC) in mid-infrared spectral region

Sanjeev, Chakrabarti P.

Opto-Electronics Review

2014

Vol. 22, No. 3

147-151

In this paper, simulation studies on an N+−InAs0.61Sb0.13P0.26/n0−InAs0.97Sb0.03/P+−InAs0.61Sb0.13P0.26 double heterostructure laser diode suitable for use as a source in a free space optical communication system at 3.7 μm at room temperature has been presented. The device structure has been characterized in terms of energy band diagram, electric field profile, and carrier concentration profile using ATLAS simulation tool from Silvaco. The current-voltage characteristics of the structure have been estimated taking into account the degeneracy effect. The results of simulation have been validated by the reported experimental results.

Performance analysis of bit error rate for free space optical communication with tip-tilt compensation based on gamma-gamma distribution

Wu H., Yan H., Li X.

Optica Applicata

2009

Vol. 39, nr 3

533-545

In this paper, the gamma - gamma probability distribution is used to model turbulent channels. The bit error rate (BER) performance of free space optical (FSO) communication systems employing on-off keying (OOK) or subcarrier binary phase-shift keying (BPSK) modulation format is derived. A tip-tilt adaptive optics system is also incorporated with a FSO system using the above modulation formats. The tip-tilt compensation can alleviate effects of atmospheric turbulence and thereby improve the BER performance. The improvement is different for different turbulence strengths and modulation formats. In addition, the BER performance of communication systems employing subcarrier BPSK modulation is much better than that of compatible systems employing OOK modulation with or without tip-tilt compensation.