Hologram recording via spatial density modulation of Nb(Li)(4+/5+) antisites in lithium niobate

• Published in: Optics express 2011-08, Vol.19 (16), p.15322-15338
• Main Authors: Imlau, M, Brüning, H, Schoke, B, Hardt, R-S, Conradi, D, Merschjann, C
• Format: Article
• Language: English
• ISSN: 1094-4087
• DOI: 10.1364/OE.19.015322

Hologram recording is studied in thermally reduced, nominally undoped lithium niobate in the time domain from 10 ns to 100 s by means of intense ns pump laser pulses (λ = 532 nm) and continuous-wave probe light (λ = 785 nm). It is shown that mixed absorption and phase gratings can be recorded within 8 ns that feature diffraction efficiencies up to 23 % with non-exponential relaxation and lifetimes in the ms-regime. The results are explained comprehensively in the frame of the optical generation of a spatial density modulation of Nb(Li)(4+/5+) antisites and the related optical features, i.e. absorption as well as index changes mutually related via the Kramers-Kronig-relation. Implications of our findings, such as the electrooptical properties of small bound Nb(Li)(4+) polarons, the optical features of Nb(Li)(4+):Nb(Nb)(4+) bipolarons, Nb(Nb)(4+) free polarons and O-hole-polarons, the impact of light polarization of pump and probe beams as well as of the polaron density are discussed.