Fabrication and characterization of high-damage resistance Zn-diffused MgO:PPLN ridge waveguides

This study investigates the fabrication process of Zn-diffused ridge waveguides in periodically poled magnesium-doped lithium niobate(PPMgO:LN).A controlled variable method is used to study the effects of diffusion temperature,diffusion time,ZnO film thickness,and barrier layer thickness on the surface domain depolarization and waveguide quality of PPMgO:LN.A special barrier layer is proposed that can automatically lift off from the sample surface,which increases the depth of Zn doping and reduces the surface loss of the waveguide.By optimizing the process parameters,we fabricate Zn-diffused PPMgO:LN ridge waveguides with a length of 22.80 mm and a period of 18.0μm.The above waveguides can make a second harmonic generation(SHG)at 775 nm with an output power of 90.20 mW by a pump power of 741 mW at 1550 nm.The corresponding conversion efficiency is 3.160%/W·cm2,and the waveguide loss is approximately 0.81 dB/cm.These results demonstrate that high-efficiency devices can be obtained through the fabrication process described in this paper.

Simulation design of thin film lithium niobate electro-optic modulator with bimetallic layer electrodes

Thin-film lithium niobate electro-optical modulator will become the key device in the future optical communication,which has the advantages of high modulation rate,low half-wave voltage,large bandwidth,and easy integration compared with conventional bulk lithium niobate modulator.However,because the electrode gap of the lithium niobate film modulator is very narrow,when the microwave frequency gets higher,it leads to higher microwave loss,and the electro-optical performance of the modulator will be greatly reduced.Here,we propose a thin film lithium niobate electro-optic modulator with a bimetallic layer electrode structure to achieve microwave loss less than 8 dB/cm in the range of 200 GHz,exhibiting a voltage-length product of 1.1 V·cm and a 3 dB electro-optic bandwidth greater than 160 GHz.High-speed data transmission test has been performed,showing good performance.

Compact yellow-orange Nd:YVO_(4)/PPMgLN laser at 589 nm

We propose and make a compact yellow-orange laser of the Nd-doped yttrium vanadate(Nd:YVO_(4))/periodically poled Mg-doped lithium niobate(PPMgLN)module by Raman frequency-doubling at 589 nm.By reasonably designing the size of the Nd:YVO_(4)and 5 mol%PPMgLN crystals,cavity length and coating parameter,a compact 589 nm laser module with a total size of 3 mm×10 mm×1.5 mm is fabricated.In the laser module,the input surface of Nd:YVO_(4)crystal is end-pumped by an 808 nm laser diode(LD).Under the effect of linear resonant cavity structure,the output surface of PPMgLN crystal with a period of 9.48μm generates 589 nm yellow-orange light.The experimental results show that the maximum output power at 589 nm is 390 mW at the pump power of 3 W with the optical-optical conversion efficiency of 13%and the stability of the output power is less than 2%within 3 h.