The feedforward linearization system of optical transmitter for Free space optical (FSO) link

Abstract

Free-space optics (FSO) or Free-space photonics (FSP), is refers to the transmission of modulated visible or infrared (IR) beams through the atmosphere, which provides the wireless solution for the demand of high speed data rate and obtain broadband communications. The problem in implementing this technology is the performance reduction due to the nonlinearity present in the directly modulated optical transmitter, hence causes the inband, harmonic and intermodulation distortion in the modulated signal. The technique of feedforward distortion compensation is one of the better solution that prefers because, it can reduce the broadband distortion in modulated optical signal of wavelength 1550 nm which is suitable for wireless optical communication, also reduces all the other higher orders of distortion and the laser relative intensity noise (RIN) simultaneously. In this paper a novel design of the free space optical link non-linearity correction of the optical transmitter i.e. laser diode at frequency 5.2 GHz bandwidth used for IEEE802.11a standard and wavelength of 1550 nm employing the feedforward linearization technique is presented.