Michael Carberry, 34, of Dumfries, was also made the subject of a community payback order.
It came with conditions that he be under supervision for 18 months and carry out 120 hours unpaid work.
Carberry, who resigned from his post following the incident, admitted one charge of sending the text message.
At Dumfries Sheriff Court, he also admitted causing the woman to look at a sexual image on her mobile phone in February last year.
A former policeman who sent an explicit text message and picture to a woman in Annan has been placed on the sex offenders register for 18 months.