Short-wave infrared broadband up-conversion imaging by using a noncritical phase matched bulk KTiOPO₄ crystal
Xiaohua Wang·Bao‐Sen Shi·Zhenghe Zhou·Jinpeng Li·Bowen Liu·He Zhang·Yin‐Hai Li·Zhiyuan Zhou·Zhao-Qi-Zhi Han
Compared to cryogenically cooled conventional detectors, up-conversion detection enables efficient room-temperature short-wave infrared (SWIR) imaging. Although quasi-phase-matching (QPM) in periodically poled crystals offers advantages, the small crystal aperture (typically 1 mm$\times$3 mm) limits resolution. Non-poled crystals enable larger apertures but suffer walk-off aberrations. This work overcomes these limitations by using a noncritical phase matched (NCPM) KTiOPO$_4$ crystal (6 mm$\tim