Due to a small effective area of erbium-doped fiber (EDF), a short pulse wi
ll be broadened because of self-phase modulation when it is amplified in an
L-band EDF amplifier (EDFA); hence, it is necessary to develop a new EDF w
ith large Er3+ concentration to reduce the EDF length and a large effective
area to reduce the nonlinear effect in the L-band EDFA. In this letter, it
will be demonstrated that the pulsewidth can be maintained when a short pu
lse is amplified in an L-band EDFA consisting of a new L-band EDF.