Pan, SM (reprint author), NE Normal Univ, Sch Phys, Changchun 130024, Peoples R China.
; Yang Hui
; Zheng Tai-Yu
; Zhang Xue
; Shao Xiao-Qiang] NE Normal Univ, Sch Phys, Changchun 130024, Peoples R China
; [Tian Tian] Chinese Acad Sci, Inst Theoret Phys, Key Lab Frontiers Theoret Phys, Beijing 100080, Peoples R China
; [Zheng Li] Dalian Polytech Univ, Informat Sci & Engn Coll, Dalian 116034, Peoples R China
We calculate the Casimir force between a perfect reflective wall and a semitransparent wall in the laser cavity. Using the Fox Li quasimode theory to describe the electromagnetic field in the laser cavity, the vacuum energy and the Casimir force are calculated. We compare our results to the force in the ideal situation and find it smaller in the dissipative cavity. We also find that the Casimir force decreases with the increase of the wall-wall distance and the decay rate of the quasimodes in the laser cavity.