Room-temperature persistent spectral hole burning in Eu3+-doped inorganic glasses: the mechanisms

High-temperature persistent spectral hole burning (PSHB), up to room temper ature, has been observed in a Eu3+- doped aluminosilicate glass and in a la nthanum-aluminosilicate one. The emphasis here is on trying to understand t he mechanism(s) leading to such a process and the effects due to changes in glass composition. Spontaneous refilling measurements show that at least t wo mechanisms, a very slow one and a faster one, are involved. The "faster" or "easy" component may correspond to a local structural rearrangement of the host and/or to photoreduction of the Eu3+ ions. We suggest that the slo w component, leading to very stable photoproducts, corresponds to transfer of an electron over a sizable distance through a multi-step process. PSHB i n the lanthanum-aluminosilicate sample requires larger irradiation doses bu t leads to more stable spectral holes. This observation is discussed, which leads us to raise the question as to whether there should be a trade-off b etween easiness and stability. (C) 2000 Elsevier Science B.V. All rights re served.