Suppressing Spectral Crosstalk in Dual-Band Long-Wavelength Infrared Photodetectors With Monolithically Integrated Air-Gapped Distributed Bragg Reflectors

Antimonide-based type-II superlattices (T2SLs) have made possible the development of high-performance infrared cameras for use in a wide variety of thermal imaging applications, many of which could benefit from dual-band imaging. The performance of this material system has not reached its limits. One of the key issues in dual-band infrared photodetection is spectral crosstalk. In this paper, air-gapped distributed Bragg reflectors (DBRs) have been monolithically integrated between the two channels in long-/very long-wavelength dualband InAs/InAs1-xSbx/AlAs1-xSbx-based T2SLs photodetectors to suppress the spectral crosstalk. This air-gapped DBR has achieved a significant spectral suppression in the 4.5-7.5-mu m photonic stopband while transmitting the optical wavelengths beyond 7.5 mu m, which is confirmed by theoretical calculations, numerical simulation, and experimental results.