Chemical imaging based on mid-infrared (MIR) spectroscopic contrast is an important technique with a myriad of applications, including biomedical imaging and environmental monitoring. Current MIR cameras, however, lack performance and are much less affordable than mature Si-based devices, which operate in the visible and near-infrared regions. Here, we demonstrate fast MIR chemical imaging through non-degenerate two-photon absorption (NTA) in a standard Si-based charge-coupled device (CCD). We show that wide-field MIR images can be obtained at 100 ms exposure times using picosecond pulse energies of only a few femtojoules per pixel through NTA directly on the CCD chip. Because this on-chip approach does not rely on phase matching, it is alignment-free and does not necessitate complex postprocessing of the images. We emphasize the utility of this technique through chemically selective MIR imaging of polymers and biological samples, including MIR videos of moving targets, physical processes and live nematodes.

基于中红外 (MIR) 光谱对比的化学成像是一项具有多种应用的重要技术，包括生物医学成像和环境监测。然而，目前的 MIR 相机性能较差，而且比在可见光和近红外区域工作的成熟硅基设备便宜得多。在这里，我们通过标准硅基电荷耦合器件 (CCD) 中的非简并双光子吸收 (NTA) 演示了快速中红外化学成像。我们证明，通过直接在 CCD 芯片上的 NTA，使用每像素仅几飞焦耳的皮秒脉冲能量，可以在 100 毫秒的曝光时间下获得宽视场 MIR 图像。由于这种片上方法不依赖于相位匹配，因此无需对准，并且不需要对图像进行复杂的后处理。我们通过对聚合物和生物样品进行化学选择性 MIR 成像（包括移动目标、物理过程和活线虫的 MIR 视频）来强调该技术的实用性。