Erbium-doped fiber ring laser tuning using an intra-cavity Fabry-Perot filter

摘要

A tunable erbium-doped fiber ring laser using an intra-cavity Fabry-Perot filter asthe tuning element is investigated. Tuning is achieved by varying the applied voltagewhich controls the FP cavity length. The laser's wavelength is monitored using an opticalspectrum analyzer to determine the laser's spectral characteristics under static conditionsat different wavelengths over its tuning range of approximately 50nm. When the laser istuned rapidly, the frequency versus time characteristic is determined using a fiber Fabry-Perot interferometer with a photodetector to convert the optical signal to an electricalsignal. The core of the research is to determine the degree of spectral broadening of thelaser as a function of the spectral tuning rate. The fringe contrast of fiber Fabry-Perotinterferometer transmittance curves decreases with increase in the tuning frequency. Thegain at a certain wavelength becomes a function of time putting an upper limit on thetuning frequency of the system. The carrier lifetime of erbium ions dictates the maximumachievable tuning speed.