A police community support officer used police databases to pester a woman with a series of unwanted emails, texts and phone calls.
Peter Kiba admitted data protection and computer misuse offences and was given an 18-month community order at Manchester Magistrates' Court.
The 59-year-old Greater Manchester PCSO was also ordered to complete 200 hours of unpaid work.
It follows an investigation by the Independent Office for Police Conduct.
The IOPC said Kiba, who later resigned, made unwanted contact with a woman in Oldham who he had "a professional association with".
She told her employer, who notified Greater Manchester Police, who in turn referred the complaint to IOPC.
The investigation found Kiba had regularly accessed the woman's personal information, including her home address and car registration, as well as those connected to her.
IOPC regional director Amanda Rowe said: "Mr Kiba abused his position by repeatedly obtaining the personal information of both the woman and people connected to her held on GMP systems without a proper policing purpose.
"His behaviour brought his professionalism into question and the sentence shows that behaviour will not be tolerated."
The IOPC referred its findings to the Crown Prosecution Service who decided to prosecute.
Det Ch Supt Jon Chadwick, head of GMP's Professional Standards Branch, said: "Peter Kiba's actions were unlawful, unprofessional and a direct breach of GMP policy.
"Such behaviour is not tolerated by GMP."