Low-Driving-Voltage Electro-Optic Modulator With Novel KTa_1-xNb_xO₃ Crystal Waveguides

Abstract

We have successfully demonstrated a low-driving-voltage electro-optic (EO) modulator using newly developed KTa1-x Nb x O3 (KTN) buried waveguides. We prepared high-quality and large KTN crystals. The crystals exhibited a large quadratic EO coefficient of 4.8×10-15 m2/V2 at 1.55 µm. The KTN crystals also exhibited a very large linear EO effect, for example 600 pm/V at a biased potential of 60 V/mm, which is twenty times larger than the r 33 of LiNbO3. The waveguide layers for the core and cladding were formed by liquid phase epitaxy techniques on the KTN crystals. The propagation loss was less than 0.5 dB/cm and the polarization dependent loss was less than 0.1 dB/cm. The EO modulators had a low V π of <2.5 V (4.0-V biased potential, l=6 mm) and a fast response of 3 GHz.

KTN-crystal-waveguide-based electro-optic phase modulator with high performance index

“…Moreover, we estimated the electric field drop of the centre core to the surface electric field by using a static electric field calculation and found it to be about 0.34. The Kerr constant, s 11 À s 12 , is estimated to be 2.6  10 À15 (m=V) 2 from (2), which is a value comparable to that of the bulk crystal [5]. These results suggest that an optimised electrode and waveguide configuration will lead to a further decrease in the V p  L value (about 0.5 cm V).…”

Influence of copper oxide on properties of potassium tantalate niobate single crystals

“…As one of widely known ferroelectric materials, potassium tantalite niobate KTa 1-x Nb x O 3 (KTN) single crystals show remarkable photorefractive effects and electrooptical properties [1,2]. Generally speaking, KTN is a solid solution of KTaO 3 and KNbO 3 .…”

Temperature dependence of Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal

“…Recently, research interests have converged on potassium tantalate niobate (KTN) crystal. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] KTN crystal, a perovskite-type oxide material, well recognized for its excellent EO performance where the index modulation is proportional to the square of the electric field, can realize rapid response, strong control of the refractive index and much lower driving energy comparing to LiNbO 3 for the same change ∆n in the refractive index. For this reason, KTN-based single crystal has been considered as promising materials, and has then been substantially investigated and successfully exploited in such diverse areas as EO deflection, [6][7][8] EO scanner, 9 a fast varifocal lens [10][11][12][13] and so on.…”

“…For this reason, KTN-based single crystal has been considered as promising materials, and has then been substantially investigated and successfully exploited in such diverse areas as EO deflection, [6][7][8] EO scanner, 9 a fast varifocal lens [10][11][12][13] and so on. 14,16,17 Mn:Fe:KTN crystal doped with both iron and manganese simultaneously are of particular interest because of its two competing subsystems of dipole moments and exhibits faster EO response than single-doped crystal. Generally, it is more significant to character the index redistribution when an electric field is applied to the photorefractive crystal and then to manipulate the OE process.…”