  A magneto-optically active thin film of Rb$_{j}$Co$_{k}$[Fe(CN)$_{6}$]$_{l}$
$\cdot$$n$H$_{2}$O has been prepared using a sequential assembly method. Upon
irradiation with light and at 5 K, the net magnetization of the film increased
when the surface of the film was oriented parallel to the external magnetic
field of 0.1 T. However, when the surface of the film was perpendicular to the
field, the net magnetization \emph{decreased} upon irradiation. The presence of
dipolar fields and the low-dimensional nature of the system are used to
describe the orientation dependence of the photo-induced magnetization. The
ability to increase or decrease the photo-induced magnetization by changing the
orientation of the system with respect to the field is a new phenomenon that
may be useful in future device applications.
