Short-wavelength laser element doped with rare earth ions, optical amplifier doped with rare earth ions, and wavelength converter doped with rare earth ions

摘要

A first pumping beam at a wavelength of 1210 nm emitted from a first pumping source is focused by a first lens system on an optical fiber. A second pumping beam at a wavelength of 650 nm emitted from a second pumping source passes through a coupler and a second lens system and arrives at the optical fiber to be incident thereon. Tm ions with which a core portion of the optical fiber is doped sequentially experience a ground-state level absorption transition upon absorption of the first pumping beam, an excited-state level absorption transition to an upper laser level upon absorption of the second pumping beam, and a radiative transition from the upper laser level to a ground-state level, thereby emitting light at a wavelength of 460 to 500 nm. The light at a wavelength of 460 to 500 nm emitted from the Tm ions is resonated by a resonator consisting of an incident mirror and an emitting mirror and outputted as a laser beam.