create a laser in xacro

Who can give me a simple example my_robot.xacro file that creat a robot which has a laser. I donot knoe how to add a laser and I try to use the .gazebo/models/hoyuko(model),but it is sdf,it maybe cannot use in xacro. Thank you very much. This is the robot.xacro without a laser.Gazebo/GreenfalseGazebo/BlueGazebo/BlackGazebo/BlackGazebo/BlackGazebo/Black