Triple-wavelength lasing at 1.50 μm, 1.84 μm and 2.08 μm in a Ho3+/Tm3+ co-doped fluorozirconate glass microsphere

Simultaneous 1.50 μm, 1.84 μm and 2.08 μm laser emission is observed in a Ho3+/Tm3+ co-doped ZrF4–BaF2–YF3–AlF3 (ZBYA) fluoride glass microsphere when pumped using a 793 nm laser diode. The ZBYA fluoride glass microsphere was prepared using a CO2 laser heating method and whispering-gallery modes (WGM) were excited when the pump light was coupled using a tapered fiber. The introduction of Ho3+ ions reduced the population of the long-lived Tm3+:3F4 level and removed the 3H4→ 3F4 self-termination effect, resulting in the population of the Ho3+:5I7 level through a resonant energy transfer process. As the 793 nm laser pump power grows, lasing occurs initially at 2.08 μm, followed by the cascade outputs at 1.50 μm and 1.84 μm. •The ZBYA fluoride glass microsphere with diameter of 47.5 μm was prepared using a CO2 laser heating method.•Ho3+ ions co-doping decreases the lifetime of the Tm3+: 3F4 level, resulting in lasing at λ~1.50 nm of Tm3+ ions.•Simultaneous 1.50 μm, 1.84 μm and 2.08 μm laser is observed in a Ho3+/Tm3+ co-doped ZBYA fluoride glass microsphere.