Compensation of output error due to the change of input intensity in an optical wavemeter based on a polarization interferometer

The optical wavemeter implemented with a polarization interferometer is simple and accurate. However, the wavemeter is very sensitive to the intensity of the input light. If the light is modulated or its intensity through the polarizer is varied due to a change of polarization state, the measurement error is increased and, in turn, the resolution and bandwidth are limited. In this study, the source of error, which is generated by a change of light intensity, is analyzed, compensated, and experimentally demonstrated. The measurement error due to fluctuated intensity can be reduced by compensating the output offset values of photo detectors. After compensation, the output errors are reduced to ±0.1 nm from ±1.85 nm at 1540 nm, ±0.12 nm from ±1.6 nm at 1550 nm, and ±0.31 nm from ±0.66 nm at 1570 nm.