A novel integrated, Resonant-cavity-frequency-selectivity Inclined-mirror Coupling Encapsulated-core Wave-Guide (RICE WG) photodetector is described. Detailed design processes and numerical simulations are investigated theoretically. The novel structure makes device’s quantum efficiency decouples with its response bandwidth and spectrum linewidth simultaneously. Through performance simulation and optimization, the results indicated that the tradeoff between spectral response linewidth and quantum efficiency no longer exist. RICE WG PIN can achieve spectral response linewidth <1nm and quantum efficiency >80% simultaneously. Additionally, we discussed the approach to realize it.