A low-loss single-polarization Y-branch pattern is fabricated on the polished surface of a lithium niobate crystal using selective proton exchange, enabling optical splitting/combining and polarizing/analyzing functions. Electrodes are fabricated on the two branch arms; applying external electrical signals independently adjusts the phase of light transmitted through the two branch waveguides, allowing the device to perform signal processing. An angled coupling technique is used between the fiber end face and the LiNbO₃ chip end face to reduce back reflection and minimize residual intensity modulation. PM fiber pigtails are precisely aligned to the axis to reduce polarization crosstalk.