Electro-Optic Property of Er3+-Doped LiNbO3 Single Crystal for Integrated Optics

Er
³⁺
-doping effect on electro-optic property of LiNbO
₃
crystal has been studied. A series of congruent LiNbO
₃
crystals homogenously doped with different Er
³⁺
concentrations up to 2 mol% in melt were grown. Unclamped electro-optic coefficients r
₁₃
and r
₃₃
of these crystals were measured by Mach-Zehnder interferometry. The results show that both r
₁₃
and r
₃₃
reveal little dependence on Er
³⁺
doping level. r
₁₃
hardly changes in the studied Er
³⁺
doping level range 0-2 mol% within the experimental error of 3%. r
₃₃
reveals a degradation tendency with a rise in the Er
³⁺
doping level, but the degradation is no more than 5% in the Er
³⁺
doping level range studied. The small effect is consistent with previous result that the performance of an electro-optic device based on Ti
⁴⁺
-diffused Er
³⁺
-doped LiNbO
₃
waveguide is not influenced noticeably by Er
³⁺
-doping. A qualitative, comprehensible explanation is given for the small effect.