Ultra-broadband frequency up-converter based on AlGaAs\GaAs heterojunction detector

Abstract

The development of high performance is essential for the realization of ultra-broadband imaging technology, which can be widely used in astronomy, medical health, defense and security, and many other applications. In this work, we demonstrate an ultra-broadband upconversion device based on a heterojunction interfacial work function internal photoemission (HEIWIP) detector and an AlGaAs/GaAs/In0.04Ga0.96 As quantum well LED. The up-converter exhibits an ultra-broad response covering from the terahertz to mid-infrared region (3–165 THz) due to free carrier absorption and inter-valence-band absorption in p-type based photodetectors. The peak responsivity in the terahertz and mid-infrared region is measured to be 7.2 A/W at 9.2 THz and 3.5 A/W at 28.8 THz, respectively, which is improved by an order of magnitude compared to the previous homojunction interfacial work function internal photoemission-based up-converter (0.5 A/W) in the THz region. The up-converter also demonstrates an improved upconversion efficiency of 1.5%. The noise equivalent power (NEP) of the imaging system consisting of the HEIWIP-LED up-converter and Si CCD is studied. The optimized NEP can achieve ∼10 pW/Hz1/2 in both terahertz and mid-infrared regions. The HEIWIP-LED up-converter exhibits excellent properties of high responsivity, ultra-broad response, and low noise, making it a great prospect for future applications in the field of ultra-broadband imaging.