Microwave Photonic Optical Wavelength Measurement Based on Swept Wavelength-to-Time Mapping

Optical wavelength measurement is crucial for various application scenarios, including metrology, sensing, lidar, etc. In these systems, a high resolution and measurement speed are generally desired, thus lots of works have been devoted to improve the resolution and speed of the measurement system. Here, we propose and demonstrate a novel microwave photonic optical wavelength measurement scheme based on swept wavelength-to-time mapping, which features a resolution better than 1.6 pm and a measurement speed as fast as 100 kHz. The key of the proposed scheme is to map the optical wavelength information to the time difference of the output pulses, by firstly filtering an electrically modulated bi-directional frequency-scanning optical reference signal and then converting the filtered signal into electrical pulse pairs. The optical wavelength under test can therefore be obtained with the help of the time domain information. Optical wavelength measurements of a single-frequency optical signal, an optical frequency comb, as well as a frequency-scanning optical signal are successfully demonstrated in the experiment. The proposed scheme offers a powerful and cost-effective way for high-resolution and fast optical wavelength measurement using microwave photonic technology, and can find a wide range of applications.