Yes, deacons can be married. However, if a wife dies, the deacon cannot remarry. At that time if the deacon would like to pursue the priesthood he may.
The diaconate is the first in a series of Holy Orders in the Catholic Church — ordained positions.
diaconate — deacon
presbyteral — priesthood
epicopate — bishop
Our archdioces has several married priests who were grandfathered in after attending theology classes. Both were former Anglican priests.