Improving detection performance of broadband QDIP indual-bands of 3–5 and 8–12 μm with photonic crystal filters

• Broadband QDIP combined with 1D photonic filter can improve detection performance.
• If photonic filter is coated on QDIP, quantum wells can be allowed to be inaccurate.
• QDIP can be easily prepared by MOCVD rather than using MBE to reduce its cost.

Due to the broadband response of a quantum dot infrared photodetector (QDIP), it is very useful for outdoor measurement of infrared radiation. The response of AlGaAs/GaAs/InGaAs-based QDIP covers the range 3–12 μm; however, the effective detection bands of outdoor measurement are only 3–5 μm and 8–12 μm. In this paper we propose an appropriate photonic crystal filter directly deposited on a detector by using an ion-assisted deposition technique, to block the unwanted low gain infrared signal in the spectral range 5.2–7.2 μm, enhancing the signal-to-noise ratio. Experimental results show that the photonic filter fabricated according to the proposed design can indeed decrease the ambient temperature of the detector, so that the detection performance of the detector is evidently enhanced. If this proposed approach is utilized the epitaxy-accuracy of the QDIP grown by metal–organic chemical vapor deposition (MOCVD) can be relaxed such that the cost of the QDIP can thus be reduced, greatly contributing to applications in the IR imaging system.