Energetic working fluid polyazide glycidyl GAP, has attracted more and more attention in the field of laser ablation micro thruster[1-3] because it can not only absorb and utilize laser energy, but also fully release its chemical energy and participate in the process of impulse formation. In order to explore the impulse coupling characteristics of solid GAP in vacuum environment, infrared dyes with different mass fraction were doped as absorbent. In a vacuum chamber with a pressure of 30 Pa, a 1064 nm Nd: YAG laser was used to test different laser energy modes (transmissive and reflective) for different thicknesses and different doping concentrations at different laser energy densities. The results show that the doped infrared dye can not significantly change the absorption threshold of laser energy by GAP, but significantly increases the deposition of laser energy in GAP. The doping concentration has a great effect on the coupling performance of the pumping amount within a certain concentration range. When the doping concentration is 5%, the momentum coupling performance of laser ablation GAP is optimal. The thickness of the GAP with the best impulse coupling performance is related to the doping concentration. The higher the concentration, the smaller the thickness of the GAP with the best ablation performance. When doped with infrared dye, GAP exhibits the body absorption characteristic of laser energy, which follows the injection mechanism of “first absorbing laser energy first injection”, so the reflective ablation mode exhibits better propulsion performance.