Numerical modeling of gain-switched dysprosium-doped yellow fiber lasers

Abstract

Compact and cost-effective pulsed yellow lasers have a growing demand for important medical applications including eye treatment, dermatology, and novel biomedical imaging. However, the efficient pulsed yellow light generation from a compact laser structure has historically been quite challenging. Recently, a dysprosium (\(\hbox {Dy}^{3+}\))-doped fiber laser has emerged as a promising candidate to produce yellow light directly and efficiently, paving the way for a simple and compact source. To date, major attention has been paid to the design of continuous wave (CW) \(\hbox {Dy}^{3+}\)-doped yellow fiber lasers. Here, we report, to the best of our knowledge, the first numerical investigation on the pulse-generating potential of a \(\hbox {Dy}^{3+}\)-doped fiber laser using a convenient gain-switching technique. With a particular emphasis on future experimental demonstrations, we consider the parameters of a commercially available \(\hbox {Dy}^{3+}\)-doped ZBLAN fiber and utilize a 450 nm pumping wavelength, which can be accessed from commercial laser diodes. In our investigation, we use a feasible peak pump power of 4 W and simulate a peak yellow output power of 11 W with a minimum pulse width (full width at half maximum) of 0.8 \(\upmu\)s at a pulse repetition rate of 25 kHz. In a \(\hbox {Dy}^{3+}\)-doped ZBLAN fiber, the lower level (\(^6\)H\(_{13/2}\)) of the yellow lasing transition has a comparable lifetime (650 \(\upmu\)s) to that of the upper laser level (\(^4\)F\(_{9/2}\)). Therefore, we also analyze the impact of the lower laser level lifetime on the gain-switching laser performance and discuss the further developmental potential.