  Using magneto-optical imaging technique, we map local magnetic field
distribution inside a hexagonally ordered array of blind holes patterned in
BSCCO single crystals. The nature of the spatial distribution of local magnetic
field and shielding currents across the array reveals the presence of a
non-uniform vortex configuration partially matched with the blind holes at
sub-matching fields. We observe that the filling fraction is different in two
different regions of the array. The mean vortex configuration within the array
is described as a patchy vortex configuration with the patches having different
mean filling fraction. The patchy nature of the vortex configuration is more
pronounced at partial filling of the array at low fields while the
configuration becomes more uniform with a unique filling fraction at higher
fields. The metastable nature of this patchy vortex configuration is revealed
by the application of magnetic field pulses of fixed height or individual
pulses of varying height to the array. The metastability of the vortex
configuration allows for a relatively easy way of producing flux reorganization
and flux focusing effects within the blind hole array. Effect of the magnetic
field pulses modifies the vortex configuration within the array and produces a
uniform enhancement in the shielding current around the patterned array edges.
The enhanced shielding current concentrates magnetic flux within the array by
driving vortices away from the edges and towards the center of the array. The
enhanced shielding current also prevents the uninhibited entry of vortices into
the array. We propose that the metastable patchy vortex configuration within
the blind hole array is due to a non-uniform pinning landscape leading to
non-uniform filling of individual blind holes.
