For the single- and dual-laser shattering of water microdroplets, the wavelength dependence of an infrared (IR) laser was experimentally examined in the range 2.25-3.75 mu m using ion current measurements coupled with time-resolved imaging. Compared to a single IR laser, simultaneous illumination by dual IR lasers effectively compresses the spatial distribution of small fragments around the absorption maximum for the OH-stretching vibration of liquid water (lambda = 2.75-3.25 mu m). The effect can be explained by the small penetration depth of the IR laser toward water microdroplets.