Inhibition of Linear Absorption in Opaque Materials Using Phase-Locked Harmonic Generation
Dipartimento di Energetica, University of Rome La Sapienza, Via Scarpa 16, Rome, Italy.Physical Review Letters (Impact Factor: 7.51). 10/2008; 101(11):113905. DOI: 10.1103/PhysRevLett.101.113905
We theoretically predict and experimentally demonstrate inhibition of linear absorption for phase and group velocity mismatched second- and third-harmonic generation in strongly absorbing materials, GaAs, in particular, at frequencies above the absorption edge. A 100-fs pump pulse tuned to 1300 nm generates 650 and 435 nm second- and third-harmonic pulses that propagate across a 450-microm-thick GaAs substrate without being absorbed. We attribute this to a phase-locking mechanism that causes the pump to trap the harmonics and to impress on them its dispersive properties.