Recently, micro cavity is studied to reduce the optical loss of BLU and OLED. In this paper, we suggest applying micro cavity to photo-luminescent lamp with plasma discharge technology to meet the display applications for a BLU for LCD. The structure of photo-luminescent lamp consists of SUS foil and ITO glass with micro cavity. The op to-elect riccharacteristics of photo-luminescent lamp with micro cavity was evaluated. The brightness of photo-luminescent device was increased over 111 ccVm2 with the adaptation of patterned micro cavity at 30 pm. The 3D optical simulation verified the enhanced light out coupling when micro cavity applied to the device.