Research Interests We, the Yamashita-Lab., are mainly focusing on photonic devices, such as fiber devices and lasers, for telecom, sensing, and medical applications, and also on their system applications. - Fast and wide wavelength tunable fiber lasers and their OCT applications We are working on the fiber lasers using Rare-earth-doped fibers or semiconductors for telecom and sensing applications. We are currently emphasizes on fast and wide wavelength tunable fiber lasers having very wide tuning range (>100nm) and a very fast tuning speed (Repetition rate > 100kHz). We are also trying to apply the lasers to the optical coherence tomography systems (OCT). - Nanocarbon photonic devices and their applications Nanocarbons, such as Carbon nanotubes (CNT) and graphene, have very interesting useful, not only mechanical and electrical, but also photonic properties. We are pursuing researches on nanocarbon photonics. We concentrate on the stable and high-energy short-pulse fiber lasers using the nanocarbons. Nanocarbons have very fast saturable absorption, which enables generation of short (~1ps) optical pulses through passive mode locking. We also demonstrated ultra-wideband supercontinuum (SC) generation using the laser as a seed source. We are trying to apply the SC source to the OCT system. - Photonic devices for telecom and sensing applications We are also working on photonic devices for telecom and sensing applications, such as wavelength converter and parametric amplifier using fiber nonlinearity, fiber lasers, and fiber filters.