High-aluminum phosphate glasses for single-mode waveguide-typed red light source

• High-aluminum phosphate (HAP) glasses are proved to be suitable for making waveguide.
• Stable single mode in visible region is achieved by K+–Na+ ion exchange.
• Larger Ω2 reveals a strong asymmetrical and covalent environment around Pr3 +.
• Quantum yield of 1D2 → 3H4 transition emission is identified to be 2.3%.
• Pr3 + doped HAP glass waveguide is a promising high-density red light source.

High-aluminum phosphate (HAP) glasses with excellent chemical durability have been fabricated and investigated for thermal ion-exchanged optical waveguide. With the content adjustment, the glass constituents turn into high-aluminum area and the glass stability has been appropriately improved with more Al3 + ions cross-linked with phosphate chains, resulting in a restriction of ion-exchange rate. Consequently, stable single-mode slab waveguide operating in visible region was fabricated on Pr3 + doped HAP glass substrates by K+–Na+ ion-exchange. For Pr3 + doped HAP glasses, Judd–Ofelt intensity parameter Ω2 is solved to be 8.04 × 10− 20 cm2, implying a strong asymmetrical and covalent environment around Pr3 + in the optical glasses. Using the Ωt values, spontaneous transition probability (Arad) and branching ratio (β) of 1D2 → 3H4 emission are calculated to be 824.3 s− 1 and 13.54%, respectively, indicating that the transition emission is dominant in visible region. The radiative lifetime (τrad) and the quantum efficiency (ηq) of 1D2 level are identified to be 164.3 μs and 87.7%, respectively, and the quantum yield (QY) of 1D2 → 3H4 transition emission is derived to be 2.3%. These results demonstrate that Pr3 + doped HAP glasses are a promising substrate in developing high-density waveguide-typed red light source, which contains attractive potential applications in medical treatment and illumination.