High-Accuracy PER Measurement of Integrated Optic Chip Using Orthogonal Alignment Method

Fiber-optic linear polarizer (LP) is a key component in measuring the polarization extinction ratio (PER) of integrated optic chip utilizing white light interferometry. Intrinsic structural imperfections in LPs, such as rotation angle deviation, however, can directly impact PER measurement accuracy. In this letter, an improved PER measurement method called orthogonal alignment method is proposed. Based on the traditional PER measurement method, a secondary measurement is carried out by rotating the axis-alignment angles of the polarization-maintaining fiber connection points from 0° to 90°. The PER measurement error induced by LPs can be then removed after calculating the average value of the two measurements. Experimental results indicate that the measurement error can be reduced to 0.02 dB for low-PER (~50 dB) measurement and to 0.1 dB for ultra-high-PER (~90 dB) measurement.