The mid-infrared (MIR) range of the electromagnetic spectrum can be indirectly accessed by frequency upconversion. Here, authors propose a phase-matching-free scheme for broadband and efficient upconversion, covering wavelengths from MIR to ultraviolet with high-order harmonics generated from a NbOI2 crystal. MIR imaging is demonstrated with a standard silicon camera.
- Song Zhu
- Xuan Mao
- Qi Jie Wang
