Abstract
Recently the shortest pulses directly out of a Ti:sapphire laser as short as 6.5fs has been generated by use of single quantum well (SQW) GaAs absorber [1]. Since this laser produces pulses with durations shorter than or comparable to the polarization dephasing time and sufficient power for Rabi flopping of the excited carrier density, the noninstantaneous response of the absorber polarization has to be taken into account. We develope the theory of coherent absorber mode locking taking into account also inhomogeneous broadening of the semiconductor transition by freely movable carriers and Coulomb renormalization of the transition frequency in the scope of semiconductor Bloch equations. Photo-echo measurements in highly excited GaAs yield a decreasing of the effective dephasing with increasing of the laser excited carrier density as T2 ∝ N-1/3. In the SQW absorber the center wavelength of 750nm is well above the bandedge of the GaAs SQW at 870nm and the broad pulse spectrum excites mainly 3D carriers above the confinement depth. We have shown that Rabi-flopping is self-consistently produced due to sub10fs pulse formation at TW/cm2 intensities corresponding to an excited carrier density up to 1020cm-3.
© 1998 IEEE
PDF ArticleMore Like This
S. Arlt, U. Siegner, F. Morier-Genoud, and U. Keller
QFE2 International Quantum Electronics Conference (IQEC) 1998
J. Herrmann, V. P. Kalosha, and M. Müller
JTuA4 Conference on Lasers and Electro-Optics (CLEO:S&I) 1997
S. Arlt, U. Siegner, F. Morier-Genoud, and U. Keller
RMD6 Radiative Processes and Dephasing in Semiconductors (RPDS) 1998