Photorefractive Effects in KNbO3

Optical nonlinearities of small polarons in lithium niobate

“…The striking role of charged point defects is reported in several prominent oxides widely applied for frequency conversion. [43][44][45] Among the materials showing polaronic effects are KNbO 3 , 46 45 Especially, the latter three materials are technologically of utmost importance for high-power laser applications. LiNbO 3 itself, particularly periodically poled LiNbO 3 (PPLN), plays an important role for low-power, tunable frequency conversion.…”

“…We like to note that all these considerations are not only valid for the nonlinear optical crystal LiNbO 3 . Polaronic effects are found in nearly any nonlinear optical crystal and are discussed at the origin of the so-called blue light-induced infrared absorption (BLIIRA) in KNbO 3 , 46,139 GRIRA 120 or gray tracking in KTiOPO 4 48,140,141 and in LiTaO 3 . 47 Furthermore, polarons limit the performance of LiB 3 O 5 (LBO) 49 and b-BaB 2 O 4 (BBO), 45 which are technologically of utmost importance for high-power laser applications.…”

Organic Photorefractive Materials and Applications

“…Several PR systems are described in the literature: besides a huge variety of inorganic crystals (BaTiO 3 , [ 36 ] KNbO 3 , [ 37 ] LiNbO 3 , [ 38 , 39 ] Sn 2 P 2 S 6 (SPS) [ 40 ] to name just a few prominent examples (for a comprehensive overview, the reader is referred to Ref. [15]), the PR effect was demonstrated in compound semiconductors (GaAs, InP, CdTe etc.…”

“…For inorganic crystals, the operational wavelength depends on the properties of the respective crystal and its doping and processing 100% internal diffraction effi ciency is never reached in practice due to internal losses. Complete internal diffraction usually refers to over-modulation of the signal (see experimental Section) in transmission geometry at η > 90%; b) interband photorefraction, here SPS at 480/532 nm; c) microcavity enhanced; [ 44 ] λ < 500 nm; k) λ = 1064 nm; [ 37 ] l) SPS, λ = 1064 nm; [ 40 ] m) 25 kHz repetition rate under imaging conditions; [ 48 ] n)…”