Spectral gain hole-burning at 1.53 mu m in erbium-doped fiber amplifiers

Theoretical and experimental study of harmonically modelocked fiber lasers for optical communication systems

“…We have shown by solving the Maxwell-Bloch equations that, when a broadband pulse propagates inside a homogeneously broadened amplifier, the saturation is determined by the overlap between the amplifier gain profile and the pulse spectrum rather than by the energy of the pulse, as is assumed in the conventional models [6], [7], [13], [14]. Since an erbium-doped fiber amplifier is essentially homogeneously broadened [15] our model was used to accurately model the saturation in our laser.…”

Modeling the saturation induced by broad-band pulses amplified in an erbium-doped fiber amplifier

“…At low temperatures ( 77 K) EDFA is inhomogeneously broadened due to the crystalline electric field that causes Stark-splitting in the energy levels of the Er atoms [5], [9]. At room temperature, the large value of the homogeneous linewidth, combined with the fast relaxation time (compared to the pulse duration) among the energy levels result in an essentially uniform homogeneous saturation across the whole gain spectrum [9]. Therefore, we neglected inhomogeneous effects as is often assumed in modeling the EDFA [3], [7], [10].…”

“…The accuracy of the results for an EDFA might be improved by using the absorption and gain cross-sections that are measured experimentally [5], [7]. At low temperatures ( 77 K) EDFA is inhomogeneously broadened due to the crystalline electric field that causes Stark-splitting in the energy levels of the Er atoms [5], [9]. At room temperature, the large value of the homogeneous linewidth, combined with the fast relaxation time (compared to the pulse duration) among the energy levels result in an essentially uniform homogeneous saturation across the whole gain spectrum [9].…”

Coherent vector π pulse in optical amplifiers

“…In these experiments, it was necessary to cool down the fiber to a few Kelvin in order to increase the homogeneous polarization lifetime T 2 up to about 10 ns. Indeed, at room temperature the transition of erbium which is resonant with 1500 nm light has a lifetime T 2 of 250 fs [8]. For femtosecond pulse durations, the non-resonant, instantaneous Kerr nonlinear response of the host silica fiber is more than six orders of magnitude larger than the resonant response [6][7], which hinders in practice coherent pulse propagation effects [9][10][11][12][13].…”