In multiphoton 3D direct laser writing and stimulated Raman scattering applications, rapid and arbitrary pulse modulation with an extremely high contrast ratio would be very beneficial. Here, we demonstrate a femtosecond fiber-feedback optical parametric oscillator (FFOPO) system in combination with pulse picking in the pump beam. This allows tunable signal output at variable burst rates from DC all the way up to 5 MHz. Furthermore, arbitrary pulse sequences can be generated. The rapid signal buildup dynamics provide individual full-power pulses with only two prepulses. This is possible without the requirement for additional injection seeding. Hereby, the intrinsically high intra-cavity losses of the FFOPO system are found to beneficial, as they enable rapid off-switching of the output as signal ring-down is efficiently suppressed. Possible applications are the reduction of the average power while maintaining a high peak power level, as well as tunable arbitrary pulse sequence generation.