Numerical Design of a Gain-Switched Pulsed Laser at 3.92 μm Wavelength Based on a Ho3+-Doped Fluoroindate Fiber

A gain-switched pulsed laser based on a commercial, heavily holmium-doped fluoroindate glass fiber, is designed to emit in themiddle-infrared range, at thewavelength lambda = 3.92 mu m. The laser, pumped at lambda = 888 nm, is modeled by a six-level system, by taking into account experimental spectroscopic parameters, to identify a feasible laser configuration. An output signal peak power of about P-s(peak) = 14.62W with a full width at half maximum (FWHM) pulse duration less than tau(s) = 73 ns and pulse energy E-s = 1.214 mu J is predicted, by considering an input peak power of P-p(peak) = 10 W, and pump repetition rate of f = 100 kHz, by employing a 8 cm-long fluoroindate fiber with holmium-concentration N-Ho = 100 000 ppm. The obtained result encourages the construction of a pulsed laser based on commercially available optical fiber, for applications in different fields as sensing and biomedicine.