Q-switched induced gain switching of a two-transition cascade laser.

A gain-switched laser transition, of a two-laser-transition cascade laser, that is driven by the adjacent laser transition which is Q-switched is demonstrated using a Ho3+-doped fluoride fiber laser. Q-switching the 5I6 → 5I7 transition at 3.002 µm produces stable gain-switched pulses from the 5I7 → 5I8 transition at 2.074 µm; however, Q-switching the 5I7 → 5I8 transition produced multiple gain switched pulses from the 5I6 → 5I7 transition. The gain-switched pulses were measured to be of a similar duration to the Q-switched pulses suggesting that much shorter pulses of closer duration could be generated at pump power higher levels.