Generation of $10μJ$ ultrashort terahertz pulses by optical rectification

Generation of near single-cycle pulses centered at $0.5THz$ frequency with up to $10μJ$ energy, $100μW$ average power, and $5.0MW$ peak power was demonstrated by tilting the intensity front of a femtosecond optical pump pulse from a $10Hz$ Ti:sapphire laser to match the phonon-polariton phase velocity to the group velocity of the pump pulses in a lithium niobate crystal. Terahertz pulse intensity as high as $10MW∕cm2$ was achieved. The photon conversion efficiency was 45% and the calculated peak electric field strength at the focus of an off-axis parabolic mirror was $250kV∕cm$⁠.