Red-diode-clad-pumped Er<sup>3+</sup>/Dy<sup>3+</sup> codoped ZrF<sub>4</sub> fiber: A promising mid-infrared laser platform
Hongyu Luo, Yongzhi Wang, Junsheng Chen, Biao Wang, Jianfeng Li, Yong Liu
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 Er 3+ /Dy 3+ codoped ZrF 4 fiber laser. A free-running laser at ∼3.4 µm, mainly from the 4 F 9/2 → 4 I 9/2 transition of Er 3+ , 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 4 I 11/2 and 4 I 13/2 states are rapidly depopulated by energy transfer to the codoped Dy 3+ ions and energy transfer upconversion between the Er 3+ 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.