Electro-Optic Modulation Performance in Kta1-Xnbxo3 Crystal

Abstract

Motivated by the demand for achieving high modulation depth of optical signal in Three-dimensional (3D) imaging LiDAR, the electro-optic (EO) modulation depth of KTa1-xNbxO3 (KTN) crystal and its stability under the electric field have been investigated. The strong field-enhanced effect of dielectric permittivity occurs owing to the dielectric resonance, the modulation depth is enhanced and half-wave voltage is further reduced.Only applying the AC electric field, the modulation depth increases with the increment of electric field and trends to remain unchanged under the high owing to the saturation of polar nanoregions (PNRs) in KTN crystal.  The modulation depth fluctuates with time, which can reduce the ranging accuracy of 3D imaging LiDAR. We found it can be attributed by the instability of PNRs.The increased modulation depth and its enhanced stability were discovered through improving the polarization and stability of PNRs by applying the DC electric field, which reveals that the DC+AC electric field can increase the ranging accuracy of LiDAR compared to the AC electric field. The study will provide guidance for designing the EO modulator for high-accuracy 3D imaging LiDAR from the perspective of Nanodomain Engineering and Electric-Field-Driven Systems.

Keywords: 3D imaging LiDAR, Electro-optic modulation, modulation depth, KTN crystal, polar nanoregions, dielectric resonance