  Polarization dependence on clamping intensity inside femtosecond filament was
experimentally measured in air. By tuning the laser pulse ellipse from linear
polarization to circular polarization, the measured clamping intensity inside
laser filament is gradually increased up to 1.7 times. The experimental results
are in good agreement with the simulation results by solving the extended
nonlinear Schrodinger equation (NLSE). The polarization sensitive clamping
intensity inside filaments offers an important factor towards fully
understanding the polarization related phenomenon observed so far.
