Origin of ellipticity anomaly in harmonic generation in C

Scanning through laser field strength and ellipticity, we show that the ellipticity anomaly in harmonic generation in C results from uneven saturations at different laser ellipticities. The smaller the laser ellipticity is, the faster the harmonic generation yield saturates with the laser strength. Harmonic generations at nonzero ellipticities take advantage of the earlier saturation at zero ellipticity, continue to grow with the laser field strength and eventually surpass the zero-ellipticity harmonic generation, which leads to the anomalous dependence. The theory predicts that the ellipticity dependence in C is much richer than those found in atoms: With an increase in laser field strength, a single maximum can be split into multiple maxima, and the global maximum comes back to zero ellipticity and reclaims its dominance over all other peaks. © 2007 Optical Society of America.