<title>Ring resonator erbium-doped fiber laser</title>

Abstract

This paper reports on an experimental study made of various laser characteristics such as threshold pump power, line width, output power etc. of an Erbium-doped fiber laser using a ring resonator geometry and comparing the results obtained with a linear resonator geometry. The EDF used in this study had a core diameter of 6.8 micrometers and an Erbium concentration of 1200 ppm-wt in a matrix of Al/P doped silica and a N.A. of 0.13. The pump wavelength used was 514 nm obtained from a CW argon ion laser. The resonator configurations studied were a ring geometry with a single plane dichroic mirror at 45 degree(s) to the pump beam. This mirror coupled 80 percent of the pump beam at 514 nm into the EDF and the reflectivity at 1.5 micrometers was 50 percent. The linear geometry resonator used a dichroic mirror with 80 percent transmittance at 514 nm and 60 percent reflectance at 1.5 micrometers . The ring resonator laser had only a single peak in the laser emission spectrum at 1550 nm for longer fiber lengths but at 1530 nm for shorter lengths of Erbium-doped fiber. The linear unbutted resonator configuration spectrum has 1 peak at 1530 nm and the emission depended on the fiber lengths employed. Experimental studies were made of the laser output power and laser spectrum as a function of input pump power, fiber length and cavity losses for both these configurations and the results obtained were compared.