We are biomedical optics lab using lasers for the observation of cells in vivo, the sensing of metabolic molecules, the diagnosis of diseases, and the development of medical devices. For the observation, we integrated home-build femtosecond lasers, scanning electronics, and microscopes into an in vivo microscopy system. On this platform, we studied embryonic development, tumor microenvironment, pharmacokinetics of nanomedicines, and in vivo cytometry of leukocytes. For the tracking of cells or drug delivery, we developed multiphoton contrast agents with nanomaterials like Si quantum dots, gold nanorod-in-shell, insulin-gold nanodot, iron oxide, and iron-platinum alloy. Exploiting the laser excited autofluorescence of metabolic molecules, we are developing spectroscopic methods for disease diagnosis. Through the discovery of characteristic optical properties in biomedical context, we aim to develop medical devices to solve the unmet clinical needs.