Methods and apparatus for increasing wavelength tuning speed in broadband mode-locked ultrafast lasers

摘要

A wavelength-tunable, ultrafast laser includes a resonator having an optically-pumped gain-medium. The resonator includes a pair of group-delay-dispersion compensating prisms and a bandwidth limiting stop. Both prisms and stop are fixed in a predetermined position relative to one another. In one embodiment, a movable beam shifting reflector is placed between the prisms. The reflector shifts the dispersed beam with respect to the second prism and the stop. The stop is arranged, cooperative with the second prism, to select a pulse wavelength within the gain-bandwidth. Tuning of the selected pulse-wavelength is accomplished by translating the beam shifting reflector. Alternatively, a two-reflector arrangement may also select pulse-wavelengths, accomplished by a combination of rotation and translation of the two reflectors. Reflector motion is controlled relative to the positions of prisms and stop such that all selected lasing wavelengths result in minimized change in laser output pulse width as the laser wavelength is tuned.