Stephen Cooperwhite, of Paisley, subjected the women to a series of sexual assaults dating back to September 2002.
The High Court in Edinburgh heard how Cooperwhite, 35, picked on the women – who cannot be named for legal reasons – at addresses in Stirlingshire and the Hebrides.
The trial heard he used force to get his way with his victims and would ignore their pleas for him to stop.
He was caught after the policewoman he abused plucked up the courage to tell bosses about what had happened to her.
Detectives launched an investigation and discovered Cooperwhite had abused another woman.
He was arrested in August 2010, just as he was completing his basic training at the Scottish Police college in Tulliallan, Fife.
Cooperwhite quit his Central Scotland Police job late last year.
The court heard that while at the college he was rumoured to be cheating on his partner with another officer.
At his trial, he claimed his victims were "bunny boilers" who had made up a tissue of lies.
But a jury of eight men and seven women refused to believe he was the innocent victim of a complicated criminal conspiracy and returned verdicts of guilty on two charges of rape.
Cooperwhite was remanded in custody and will be sentenced at the High Court in Glasgow next month.
He used force to get his way and ignored victims' pleas to stop