An optimized Yb: doped fiber mode-locked oscillator and fiber amplifier system for seeding Nd: or Yb: doped regenerative amplifiers. Preferably, a set of data storage devices are used to store heterogeneous data, i. A plurality of semiconductor chips may be stacked the substrate, and each of them may include at least one electrode pad. The fillers are interposed between each piezoelectric ceramic element and the actuator base to secure a clearance for electrical insulation between the two.