TY - JOUR KW - pfc AU - T. Allison AU - Arman Cingöz AU - D. Yost AU - Jun Ye BT - Physical Review Letters DA - 2011-10 DO - 10.1103/PhysRevLett.107.183903 PY - 2011 SE - 183903 EP - 183903 T2 - Physical Review Letters TI - Extreme Nonlinear Optics in a Femtosecond Enhancement Cavity VL - 107 ER -