Upconversion of VIS/NIR detectors for Mid-IR detection

Opportunity  

Mid-infrared (MIR) detection is essential for applications such as environmental monitoring, thermal imaging sensors and remote sensing. Conventional infrared photodetector materials, including indium antimonide (InSb), mercury cadmium telluride (MCT) and Type-II superlattice (T2SL), face challenges related to cost, size and sensitivity. The demand for compact, affordable and CMOS-compatible solutions is driving interest in silicon photonic upconversion for MIR detection. 

This innovation leverages well-established visible/near-infrared photodetectors to upconvert MIR signals, eliminating the need for costly cryogenic cooling. Its ability to enhance MIR detection using low-cost silicon-based systems makes it a scalable solution for next-generation spectrometers, imaging systems and industrial sensors. 

Technology  

This upconversion nanotransducer utilises NaYF₄ doped with Nd³⁺/Yb³⁺, where Nd³⁺ absorbs NIR radiation efficiently, facilitating energy transfer to Yb³⁺, resulting in strong NIR emission. Moreover, highly absorptive surface ligands act as MIR energy harvesters, enhancing detection efficiency. The system also integrates seamlessly with silicon-based photodetector, achieving responsivity and detectivity comparable to the commercial MCT detectors.  

By harnessing thermal excitation from molecular vibrations, this nanophotonic MIR sensor enables high-sensitivity mid-IR imaging, making it ideal for scientific, industrial and environmental applications. 

Figure 1. Energy transfer between Yb³⁺ to Nd³⁺ and the Mid-IR up-conversion. 

Applications & Advantages 

Applications: 

• Thermal imaging sensor – Fire detection, security and industrial monitoring. 
• Remote sensing – Detects gas leaks and hazardous substances.
• Engine and exhaust system monitoring – Improves efficiency and safety. 

Advantages: 

• Low-cost MIR to NIR conversion for scalable imaging solutions. 
• CMOS-compatible silicon photonic upconversion, ideal for mass production.
• Compact, highly sensitive alternative to conventional MIR detectors.