Waveguide Amplifier for Extended Reach of WDM/FSO

*Bentahar Attaouia, Kandouci Malika, Ghouali Samir and Dinar Amina Elbatoul*

## **Abstract**

In this chapter, EYDWA (erbium ytterbium doped waveguide amplifier) is characterized for wavelength division multiplexing (WDM) approach on free space optical (FSO) transmission systems with channels being spaced at 0.4 nm interval. Moreover, in this paper, was study different characterizations of EYDWA amplifier, which depend essentially on the opt-geometric parameters, such as concentrations of ions erbium, length of the waveguide and the effect of those parameters to optimize the performance of proposed system. Furthermore, the results reveal that the EYDWA booster (post-amplification) can improve the high performance remarkably under clear rain and the acceptable transmission can be carried out up to 26 km while it get reduced to 19.5 km by using pre-amplification.

**Keywords:** free space optical, BER, EDWA, WDM, atmospheric condition

## **1. Introduction**

FSO (free space optics) is an optical communication technology in which contains three components: transmitter, free space transmitted, and receiver. The transmitter requires light, which can be focused by using either light emitting diode (LED) or laser (light amplification by stimulated emission of radiation) to transmit information through the atmosphere. At the receiver, a photodiode converts the optical intensity signal back into an electrical signal and the information is recovered [1, 2].

The FSO communication system has the advantages of unrestricted spectrum and high-speed transmission over other wireless communication systems. This system is likely to replace other wireless communication systems in many fields and become the solution for last-mile communication. The main limitation of FSO is seen in worse weather conditions where it suffers highest attenuation [3].

Optical network that apply wavelength division multiplexing (WDM) is currently widely used in existing telecommunications infrastructures and is expected to play a significant role in FSO system supporting a large variety of services having very different requirements in terms of bandwidth capacity which ensures multiservice and multicasting opportunity [4, 5].

WDM FSO systems use a single light beam to transmit the multiplexed signal through free space [6]. A multiplexer is used at the transmitter to combine different modulated carriers and a demultiplexer at the receiver to restore each one (**Figure 1**).

**Figure 1.** *The system setup of WDM-FSO.*
