Optical transfer delay measurement with enhanced range and accuracy via vernier scale readout principle

An optical transfer delay (OTD) measurement method based on the vernier scale readout principle is proposed to simultaneously enhance the measurement range and accuracy. In this work, two detuned microwave signals modulate an optical carrier, which is then injected into a high-precision swept optical delay line (ODL)-integrated optical-carrier microwave interferometer. This process generates two power-delay profile diagrams exhibiting slightly detuned delay characteristics, from which the target OTD can be precisely extracted via the vernier scale readout principle. Simulation and experimental studies were conducted to evaluate the proposal.