Design of a Mid-IR Laser Based on a Ho:Nd-codoped Fluoroindate Fiber

Abstract

In this work, a novel mid-infrared continuous wave laser, based on a fluoroindate fiber co-doped with holmium and neodymium, is designed to emit at 𝝀 𝒔 = 𝟑. 𝟗𝟐 𝝁𝒎, when pumped at 𝝀 𝒑 = 𝟖𝟎𝟖 𝒏𝒎. The laser is modeled considering a nine-level system, by taking into account experimental spectroscopical parameters. Since the energy transfer coefficients are unknown, they have been evaluated starting from the measured emission spectra of the bulk glass, reported in literature, and comparing their ratio with respect to the ratio between the simulated signal gain coefficients. The designed laser promises higher slope efficiency and power threshold lower than those obtainable with a holmium-heavilydoped fiber, having same fiber section geometry, same refractive indices and pumped at 𝝀 𝒑 = 𝟖𝟖𝟖 𝒏𝒎. Slope efficiency 𝜼 = 𝟏𝟔. 𝟔𝟕% and input power threshold 𝑷 𝒕𝒉 = 𝟎. 𝟐 𝑾 are obtained for the fiber length 𝑳 𝒇𝒊𝒃𝒆𝒓 = 𝟎. 𝟒 𝒎, dopants concentrations 𝑵 𝑯𝒐 = 𝟖 × 𝟏𝟎 𝟐𝟔 𝒊𝒐𝒏𝒔/𝒎 𝟑 and 𝑵 𝑵𝒅 = 𝟏 × 𝟏𝟎 𝟐𝟔 𝒊𝒐𝒏𝒔/𝒎 𝟑 , and output mirror reflectivity 𝑹 𝒐𝒖𝒕 = 𝟔𝟎%. This result encourages the fabrication of a continuous wave laser based on a Ho:Nd-codoped fluoroindate fiber.

Numerical Modeling of Dual-Wavelength Pumped Heavily-Ho3+-Doped Fluoroindate Fiber Lasers With Efficient Output at 3.92 μm

“…The resulting higher 1660nm pump power also does not enable laser enhancement. If the new co-doping scheme is adopted [17] in the subsequent work and the cascade system [11] is used, the efficiency will be improved even more.…”

“…In a study conducted in 2023, Loconsole et al employed a nine-level system to simulate the variation of a Ho: Nd-codoped fluoroindate glass fiber. They achieved laser emission at 3.92 μm by employing an 808 nm pump laser, resulting in a slope efficiency (η) of 16.67% and an input power threshold (P th ) of 0.2 W [17].…”

Analysis and Optimization of Dysprosium-Doped Yellow Fiber Lasers for Ophthalmology Applications

“…Various coefficients used in the system of Equations 1-6 are defined in Table II. In Table II, P represents the power (for the pump, signal, or amplified spontaneous emission), σ 12 (21) is the absorption (or emission) cross-section between energy levels 1 and 2 (2 and 1), h is the Planck constant and ν is the frequency of the radiation.…”

“…In that work, Dy−doped multi-component phosphate core glass fiber was successfully drawn by using a rod-in-tube method. Fluoride fibers have been recently employed to build novel Mid-IR sources as well [21], [22]. Furthermore, in [23], another Dy−doped NaLa(WO 4 ) 2 glass ceramic fiber with good uniformity was fabricated using the molten core method showing that it can be a very promising material candidate for tunable yellow lasers [23].…”

Design of a High Performance Mid-IR Fiber Laser Based on Pr3+-Doped Fluoroindate Glass

“…They can be integrated in all-in-fiber systems, by employing couplers, combiners, and Fiber Bragg Gratings (FBG), to obtain compact and low-loss architectures [3][4]. Fiber lasers and amplifiers can be fabricated with several glasses, depending on their operation wavelength range, including silicate, tellurite, chalcogenide, and fluoride, doped or co-doped with different rare-earth ions, such as erbium, ytterbium, holmium, praseodymium, neodymium, or europium [5][6][7][8][9][10][11][12][13][14][15][16]. Fluoroindate glasses are promising hosts thanks to their low phonon energy (≈ 510 cm −1 ), high transparency from UV till 5 μm wavelength (𝛼 < 1 𝑑𝐵/𝑚), and high rare-earth ions solubility [6].…”