White light emission based on both upconversion and thermal processes from Nd3+ doped yttrium silicate

Broadband light emission induced by laser absorption and optimized by thermal injection in Nd3+:Y2SiO5 ceramic powder

“…It has a slope of ~4 at low excitation power levels, a slope of ~1 for intermediate excitation power levels and change to ~8 at high excitation power levels. A similar behavior has been observed before with the authors suggesting a combination of thermal and avalanche effects as responsible for the unusual change in the slope. It is interesting to note that the avalanche effect alone cannot generate broadband emission, as it is not present in the sample containing 2 wt% of Nd 3+ .…”

“…The phenomenon is shown in atmospheric pressure with the 808‐nm CW excitation laser threshold around 1.3 W. This laser threshold is much lower than that reported in Ref. and the difference may be due to a series of factors such as excitation conditions, sample preparation method, doping concentration, and particle size. More importantly, we observed for the first time to the best of our knowledge that broadband emission intensity is enhanced by externally heating the sample, which also produced a lowering of the laser threshold to around 1.0 W in ambient air.…”

“…Figure shows the up‐conversion data obtained at ambient pressure and temperature for our YS samples containing two different Nd 3+ doping concentrations. Figure A shows emission bands corresponding to 4f‐4f radiative electronic relaxations of Nd 3+ in YS host . It is observed that the emission profiles do not change much with the excitation power.…”

“…However, performing a linear best fit on the experimental data provided a slope of ~4 for the sample containing 2.0 wt% of Nd 3+ . Slopes higher than what it is expected from an ordinary up‐conversion mechanism have been assigned as characteristic of photon avalanche . The sample containing 4.0 wt% of Nd 3+ presents a more complicated behavior.…”

“…For applications as a phosphor, we have demonstrated that Eu 3+ ‐doped YS has higher luminescence quantum efficiency than the standard red phosphor Eu 3+ ‐doped yttrium oxide . Recently, Cinkaya and coworkers have demonstrated broadband (white) up‐conversion emission in Nd 3+ ‐doped YS . The authors have shown that the 808‐nm continuous‐wave (CW) excitation laser threshold to obtain white light emission decreased from around 5.8 W to around 3.5 W when the pressure was reduced from atmospheric to vacuum (0.01 mbar).…”