He also has to attend a psychological assessment and have treatment and counselling as directed.
Throughout the 90-minute sentencing, the defendant stood impassively in the dock, his eyes downcast.
About 10 people were in the public gallery, the majority in support of the defendant.
Judge Phillips said the sentence was appropriate to provide for the defendant's rehabilitation and reintegration into the workforce.
Crown prosecutor Craig Power said the offending was for the defendant's sexual gratification. It was premeditated and he knew what he was doing was wrong.
In mitigation, the defendant was a first offender, had pleaded guilty early and a "positive" restorative justice conference had been held with the victim.
Judge Philips said as a police officer, the man would be aware of the harm caused by "this type of offending".
He declined the defendant's request for a discharge without conviction. Counsel Nic Soper called it "low-level" offending and said the consequences of a conviction would outweigh the gravity of the offence, but the judge rejected that submission.
"The consequences of the offence, direct or indirect, are not out of proportion to the gravity of the offence, because I consider the gravity of the offending is serious," Judge Phillips said.
The maximum penalty for the charge was three years in jail.
At the time of the offending, the man was under considerable pressure at work and at home, Judge Phillips said.
Mr Soper had tabled a report by a clinical psychologist, along with several "glowing references" about the defendant.
The Otago Daily Times opposed the man's name being suppressed.
ODT counsel Bill Wright said name suppression would place "the finger of suspicion" on other, innocent, former police officers and speculation would be rife about the identity of the man.