He then took the officers keys and access card and fled the courthouse.
Police found him some time later hiding under a jetty.
The officer was left with bruising on his head and face that was still visible a week after the attack.
Judge Crayton said although the injuries could be considered "moderate" the officer has experienced considerable mental stress.
"He found the attack extremely disturbing," he said.
"What should be a duty without fear and stress has become for him, fearful and stressful."
Judge Crayton said it was troubling Poulson knew the officer but "blindsided" him nonetheless.
"Your interactions with [the victim] had always been good."
"This was a thoroughly cowardly attack in which the victim was vulnerable."
"Your only thought was escape."
He said while Poulson expressed remorse in the form of a letter to the officer and a willingness to engage in restorative justice, there are particular sentencing laws that must be taken into account when a defendant attacks a custodial officer.
"There is a need to deter others who consider offending in this way," he said.
Judge Crayton also sentenced Poulson for separate charges related to an attack on his partner at the time.
He told the court on the evening of April 13 Poulson entered the home of the victim.
Poulson gathered knifes from the kitchen and placed them around his partners bed while she was sleeping with their son.
He then attacked her striking the face and shoulder area.
The victim woke screaming.
As she attempted to cover her head, he struck her hands and torso.
In a impact statement the victim said she was "terrified" of Poulson.
"She is scared of the day you will be released," he said.
He noted the disturbing nature of the attack.
"The use of knifes as intimidation is particularly troubling."
"And that she had her son, your son, in her arms."
Poulson had previously pleaded guilty to the attack and was due to be sentenced when he escaped custody on April 19.
He was sentenced to four years and two months prison for both separate offences.
