Design of a Pr3+:InF3 Fiber Laser Pumped in near-IR and Emitting at 4 micron Wavelength

The design of a novel continuous wave laser, based on a fluoroindate fiber, doped with praseodymium, is proposed. The laser is optimized to emit a beam at λs= 4 μm, when pumped at λp= 1500 nm, by employing a homemade computer code and by considering measured spectroscopical parameters taken from literature. Several simulations are performed by varying the laser cavity length and the output mirror reflectivity. Good efficiency and low input power threshold have been obtained as promising results.

1. INTRODUCTION

Fiber lasers have attracted much industrial and research interest in the last years, due to their feasible and promising applications, including environmental and agrifood monitoring, communications, industrial material processing and medical diagnostic and therapy, also combined with other techniques [1] - [8]. Moreover, all-in-fiber integration allow more compact and reliable devices [7], employing gratings, couplers, and combiners. Fiber lasers can be designed considering different glasses, such as silicate, germanate, chalcogenide, tellurite, and fluoride ones, doped or co-doped with several rare-earth ions, including erbium, holmium, thulium, neodymium, europium, and praseodymium [1] - [7], [9] - [12]. Fluoroindate glasses show a low phonon energy (≈ 510 cm⁻¹), a high rare-earth ion solubility, and high transparency in the 3 − 5 μm window. These properties make them ideal host materials for rare-earth ions, overall to be exploited for middle-infrared (Mid-IR) applications. During the last years, many continuous wave (CW) and pulsed lasers based on fluoroindate fibers, emitting in the 3 − 5 μm wavelength window, have been proposed and have shown promising results [1], [7], [10] - [12].