Red-diode-clad-pumped Er3+/Dy3+ codoped ZrF4 fiber: A promising mid-infrared laser platform

Abstract

We report, for the first time, to the best of our knowledge, mid-infrared (mid-IR) laser generation, from a red-diode-clad-pumped Er3+/Dy3+ codoped ZrF4 fiber laser. A free-running laser at ∼3.4 µm, mainly from the 4F9/2→4I9/2 transition of Er3+, directly excited by a 659-nm laser diodehas been achieved at room temperature with a maximum power of 0.8 W and 8.8% slope efficiency. In this system, the long-lived 4I11/2 and 4I13/2 states are rapidly depopulated by energy transfer to the codoped Dy3+ ions and energy transfer upconversion between the Er3+ ions, resulting in the accelerated recycling of ions. Additionally, the free-running dual-wavelength operation state at ∼3.3 and ∼3.5 µm is also observed, producing a total maximum power of 0.95 W with 10.7% slope efficiency, representing the first watt-class output from a diode-pumped rare-earth-doped fiber laser far beyond 3 µm. By employing a diffraction grating, continuous spectral tuning across the 642-nm range from 3053.9 to 3695.9 nm has been demonstrated. The proposed scheme provides, to the best of our knowledge, a promising new platform for laser generation in the mid-IR region of 3–4 µm.