Isfahan University of Technology

Department of Electrical and Computer Engineering

Issue date: September, 2018

Degree: MSc

Language: Farsi

Contributor: Ehsan Hamidnejad

Supervisor: Dr. Asghar Gholami

Abstract

High power fiber lasers and amplifiers in 1.5µm band are interested for many application such as free space communication, material processing, LIDAR and medicine. Eye safe nature, low transmission loss (free space and fiber), light weight and compactness make it of great advantage over solid state laser.

In this research, we present numerical solution of CW and pulsed Erbium/Ytterbium codoped fiber amplifiers. Then, we show influence of designing parameter on performance of fiber amplifiers and length of active fiber, pump pulsewidth and delay between entrance pump and signal are selected. To reduce amplified spontaneous emission (ASE), pump pulsewidth is decreased and to control stimulated brillouin scattering (SBS) the pump power is limited.

After implementation of designed Er/Yb codoped fiber amplifier, we demonstrated that measurement and simulation results have a good matching. Finally, 74.6µJ energy and 35dB difference between signal and ASE spectral amplitude was achived at repetition rate of 4.7KHz.