A Calibration Method for Large Dynamic Range White Light Interferometry Using High-Order Polarization Crosstalk

This paper presents a method to calibrate a large dynamic range white light interferometer (WLI) using high-order polarization crosstalk. The whole calibration range is divided into three parts. The first part is the measurement range of the polarization extinction ratio (PER) meter. The intensities of polarization crosstalk at the coupling points (first-order polarization crosstalk) are adjusted in this range. Their intensities are measured by a calibrated PER meter. The second and third parts are the double and triple measurement range of the PER meter, respectively. The intensities of polarization crosstalk generated by multiple coupling points (high-order polarization crosstalk) can be calculated from those of first-order polarization crosstalk. The second- and third-order polarization crosstalk will increase the calibration range by a factor of 2 or 3, respectively. The calibration device based on a Y-waveguide has been studied both theoretically and experimentally to avoid high-order crosstalk overlap. A WLI with 100 dB dynamic range is calibrated using this method.