Green-induced blue absorption in MgO-doped lithium niobate crystals

Abstract

We have measured the intrinsic and 532 nm-induced optical absorption of 5 mol. % MgO-doped lithium niobate crystals at 488 nm wavelength. The measurements have been conducted employing a photothermal common-path interferometer. The absorption at 488 nm increases on simultaneous illumination with 532 nm light. This induced absorption rises linearly with the stimulating 532 nm radiation power and saturates for intensities larger than 50 kW/cm(2). A model developed recently, considering the excitation of electrons from levels near the valence band into iron centers, is applied to explain the observations.

Pulse-induced transient blue absorption related with long-lived excitonic states in iron-doped lithium niobate

“…The formation of O − -hole polarons with strong coupling is in full accordance with the original expectations formulated by Schirmer et al for nearly all polar oxide crystals [6]. Later on, investigations with continuous wave [7] and pulsed laser light [8,9], however, revealed several discrepancies to the hole polaron model. The results of Waasem et al [7] demanded for the existence of further electronic states within the band-gap, being handled as X-center of unknown microscopic nature.…”

“…Later on, investigations with continuous wave [7] and pulsed laser light [8,9], however, revealed several discrepancies to the hole polaron model. The results of Waasem et al [7] demanded for the existence of further electronic states within the band-gap, being handled as X-center of unknown microscopic nature. Quite recently, Messerschmidt et al discussed excitonic states at the origin of long-lived transient blue absorption [9].…”