The frequency converter is prepared by using periodically polarized lithium niobate ridge waveguide, which can realize efficient narrow-band frequency doubling in 1560 nm band. If other bands are required, it can be customized. Different lengths and types of fiber interfaces can be provided according to customer frequency conversion requirements, and the overall insertion loss of the device is less than 4 dB. The frequency multiplier has an efficient nonlinear frequency conversion capability, which can meet the frequency doubling needs under various powers. Under the milliwatt small signal, the normalized frequency doubling efficiency reaches 335%/W*cm². Under the watt-level power input, the frequency multiplier can achieve an absolute conversion efficiency of more than 30%, and can still maintain a stable conversion under long working time, and the efficiency fluctuation is within 0.3%. At the same time, the frequency multiplier can control the frequency doubling wavelength by adjusting the temperature, and the temperature tuning ability is 0.15 nm/℃, and the frequency doubling ability is not affected by temperature and wavelength.