PC Jayson Lobo, 46, from Blackburn, Lancashire, is accused of 18 offences of sexual spying allegedly committed between December 2011 and May 2015.
The former Commonwealth Games runner appeared at Liverpool Crown Court and was released on bail ahead of a trial on 16 January.
The Preston-based response officer was suspended after his arrest in December.
The offence of voyeurism is defined as watching people engaged in a private act without their consent for sexual gratification.
A police officer and former UK middle distance athlete has denied voyeurism offences involving eight women.