In this paper, we report on a minized length, compact, low loss Y-branch waveguide based on lithium niobate optical crystal. The Y-branch waveguide device was fabricated using annealed proton exchange technique to achieve single mode guiding at 1550 nm wavelength. The simplified Y-branch structure has a total length of 18.7 mm and calculated bending loss of 0.5 dB has been realized with a splitting ratio found to be 1.25 at 1550 nm wavelength. Such easy to fabricate waveguide could find applications in future photonic communication networks, sensing, and quantum information technology.
Here we report that the properties of the poling electrode is one of the most important factors in fabrication of the ferroelectric crystal poling. In this paper, systematic researches on the property of electrode coating and the forms of electrode contact have been made. By using pulse applied electric field, the periodically poled grating of 31.2μm was prepared on a 1mm thick 5% MgO-doped Lithium Niobate crystal. A wavelength of 1064nm pulse laser was used as fundamental source to operate optical parametric oscillation experiment, and 1.141W of idler output power was obtained when PPMgOLN pumped by 1064nm of 5.567W at the temperature of 80℃. The maximum conversion efficiency from incident pump power to the idler output achieved to 20.1%.
Periodically poled crystals are widely used as SHG, DFG, SFG, OPO and THz generation, and there is a broad application prospect in some areas such as the laser display, optical fiber communication, atmospheric exploration and military confrontation. At present, to get the parameters of periodically poled crystals, like duty ratio, the main method is chemical etching of the samples. In this paper, we present a nondestructive characterization system of periodically poled crystals. When we apply a proper high voltage on both sides of the periodically poled crystal, the refractive index difference of positive and negative domain will be increased and we can observe a clear domain pattern by the a microscope so as to obtain general information. Then a single frequency laser is prepared to radiate on +z surface of the periodically poled crystal, we can get some orders of diffraction according to diffraction optics principle. Finally, we can measure the parameters such as period, duty ratio by use of numerical analysis. The testing sample size of this system can be up to 60mm, The accuracy of the testing period can be 0.1μm, and the measurement range of duty ratio is 20%-50%.