The former jail guard earlier plead guilty to both incidents, the first of which occurred between 2003 and 2005 at the jail on Old Black River Road, the second at the city lock-up between 2009 and 2010.
Allen maintained the sex was consensual and his lawyer asking for a conditional sentence so he could receive therapy for sexual addiction.
The judge awarding jail time on the grounds that Allen was in a position of authority when the act occurred, and he did not seek counselling for his illness until after he was charged.
Allen will also serve two years of supervised probation.
