  Four Ophiuchus binaries, two Class I systems and two Class II systems, with
separations of ~450-1100 AU, were observed with the Owens Valley Radio
Observatory (OVRO) millimeter interferometer. In each system, the 3 mm
continuum maps show dust emission at the location of the primary star, but no
emission at the position of the secondary. This result is different from
observations of less evolved Class 0 binaries, in which dust emission is
detected from both sources. The nondetection of secondary disks is, however,
similar to the dust distribution seen in wide Class II Taurus binaries. The
combined OVRO results from the Ophiuchus and Taurus binaries suggest that
secondary disk masses are significantly lower than primary disk masses by the
Class II stage, with initial evidence that massive secondary disks are reduced
by the Class I stage. Although some of the secondaries retain hot inner disk
material, the early dissipation of massive outer disks may negatively impact
planet formation around secondary stars. Masses for the circumprimary disks are
within the range of masses measured for disks around single T Tauri stars and,
in some cases, larger than the minimum mass solar nebula. More massive primary
disks are predicted by several formation models and are broadly consistent with
the observations. Combining the 3 mm data with previous 1.3 mm observations,
the dust opacity power-law index for each primary disk is estimated. The
opacity index values are all less than the scaling for interstellar dust,
possibly indicating grain growth within the circumprimary disks.
