Experimental evaluation & determination of free space optical link performance at 532nm wavelength under rain attenuation conditions & its comparison with 850nm wavelength

Free Space Optics (FSO) communication is a demanding efficient wireless technology which have been accepted due to its low power and mass requirements, high data rates and unlicensed spectrum. Atmospheric disturbances have a significant impact on performance of FSO Link which results in the degradation of the laser beam. In this paper, the analysis and investigation based on experimental set-up for a Free Space optical communication link at wavelength of 532nm and 850nm is being carried out which helps to evaluate the link performance and further improvement in link performance is done by experimental arrangement. The FSO link in case of 532nm tolerate attenuation up to 66.12 dB/km at the loss of -0.04 dB and rain rate of 2.3592mm/min. whereas 850nm tolerate attenuation up to 17.5 dB/km at the loss of -0.01 dB and at the same rain rate as in 532nm. The experimental investigation is carried out by analyzing the receiver current, exposed length and rain rate conditions. It is concluded that the proposed FSO link of 532nm having more attenuation than 850nm wavelength and in the both the cases loss is assumed of -0.01 dB. There is an increase in attenuation when rain rate increases. The rain rate over the exposed lengths depends on the different rain drop sizes. So it can be said that visible wavelengths due to its low cost, low power consumption and easy detection is good for short range communication purposes than infrared wavelengths.