Efficient energy transfer from Er3+ to Ho3+ and Dy3+ in ZBLAN glass

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

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 ⁴F_9/2→⁴I_9/2 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 ⁴I_11/2 and ⁴I_13/2 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.

Widely wavelength tunable Dy3+/Er3+ co-doped ZBLAN fiber lasers

Wavelength tunable dysprosium-erbium (Dy³⁺/Er³⁺) co-doped ZBLAN (ZrF₄-BaF₂-LaF₃-AlF₃-NaF) fiber lasers pumped at 980 nm were developed with a bulk grating blazed at 3.1 µm in the Littrow configuration and their performances were investigated. A wavelength tunable range of 674.4 nm (2709.2 nm -3373.6 nm) was achieved with a 4.5-m 0.25 mol.% Dy³⁺/ 4 mol.% Er³⁺ co-doped ZBLAN fiber. Our experiments demonstrated that either Er³⁺ or Dy³⁺ can be lasing individually in a Dy³⁺/Er³⁺ co-doped ZBLAN fiber and a fiber laser with wavelength tunable range from 2.7 µm to 3.4 µm or longer wavelengths can be achieved with proper fiber and cavity design.

13-W and 1000-Hz of a 2.7-µm laser on the 968 nm LD side-pumped Er:YAP crystal with concave end-faces

We demonstrate a 968-nm LD side-pumped Er:YAP laser with concave end-faces and a working frequency of 50∼1000 Hz. The maximum average powers of 26.75 and 13.18 W are obtained at 250 and 1000 Hz, corresponding to the slope efficiency of 16.2% and 9.0%, respectively. The M2 factors of 7.98 and 1.49 are determined under the multi-mode and single-mode, and three laser wavelengths of 2713, 2732 and 2796 nm are observed. The results indicate that the LD side-pumped Er:YAP crystal with negative curvature end-faces is a promising candidate for the high power and high frequency mid-infrared laser device.

Broadband mid-infrared amplified spontaneous emission from Er/Dy co-doped fluoride fiber with a simple diode-pumped configuration

Er³⁺/Dy³⁺ co-doped double-clad ZBLAN optical fiber has been used to obtain amplified spontaneous emission (ASE) broadband light sources cladding-pumped by 980-nm multimode laser diode (LD) sources. It has been demonstrated that mid-infrared broadband emission extending from 2515 to 3735 nm was obtained by energy transfer between Er³⁺ and Dy³⁺. We experimentally investigated the optimum design of Er³⁺/Dy³⁺ co-doped ZBLAN fiber in terms of ion concentration, fiber length, pumping configuration, and pumping power. The ASE output power was more than 2.5 mW when the LD pump power was set at 5 W. To assess its potential for gas sensing applications, the fabricated ASE light source was used to successfully detect methane gas with concentrations at 1% and 5%. The simple and stable construction of our ASE light source is suitable for practical purposes.