Flags will be flown at half-mast at police stations throughout the county.
Sergeant Graham Saville, a response officer based at Newark Police Station, sustained serious injuries when he was hit by a train as he attempted to save a distressed man.
The incident happened in Balderton just before 7pm on Thursday 24 August.
Sergeant Saville was taken to Queen’s Medical Centre where, despite the best efforts of medical staff, the 46-year-old died on Tuesday 29 August with his family at his bedside.
Flags across the force will now be flown at half-mast as a mark of respect.
Speaking on 29 August Chief Constable Kate Meynell said: “Today is a day of mourning for the entire police family.
“Graham was a hugely respected and popular colleague and his death in the line of duty has come as an enormous shock to us all.
“Our hearts and deepest condolences go out to his family and we will do everything we can to support them through this unimaginably devastating time.
“It is impossible to put into words how devastating this news is for everyone who loved and respected Graham.
Sergeant Saville’s family has requested that their privacy be respected.
An investigation into the incident, led by British Transport Police, is ongoing.