Single and two-photon fluorescence control of Er³ ions by phase-shaped femtosecond laser pulse

We experimentally demonstrate the control of the single and two-photon fluorescence (SPF and TPF) in Er³ ions by shaping the femtosecond laser pulse with a π or square phase modulation. With the low laser intensity (8.4 × 10¹⁰ W/cm²), SPF keeps a constant while TPF is effectively suppressed by the two control schemes. With the high laser intensity (1.2 × 10¹³ W/cm²), both SPF and TPF are simultaneously enhanced or suppressed by the π phase modulation, and SPF is enhanced while TPF is effectively suppressed by the square phase modulation. The up/down-conversion fluorescence enhancement, suppression, or tuning by the optical control method can greatly expand its applications in various related fields.