A wavelength-tunable laser is a powerful tool as light source for sensing and its research and development has been studied so far. In order to obtain a new tunable laser the authors have developed a tunable Er3+-doped fiber laser in Littman/Metcalf configuration, and incorporating a Galvano mirror, scanning of the lasing wavelength is demonstrated. For the emission range that a semiconductor-based light source hardly covers, a tunable Tm3+-Ho3+ fluoride fiber laser is also demonstrated.