Instantaneous photonic microwave frequency measurement with a maximized measurement range

The use of photonic techniques to achieve frequency-to-power mapping is very attractive for instantaneous microwave frequency measurement. To have a large measurement range and a uniform measurement resolution in the range, to accurately evaluate the center frequency of a continuous-wave (CW) as well as a pulsed microwave signal, and to easily perform calibration of the measurement system, a linear amplitude comparison function (ACF), defined as the ratio of two powers of the microwave signal experiencing different power fading, is highly desirable. In this paper, we propose and demonstrate, for the first time, a novel technique to achieve a linear ACF for microwave frequency measurement with a maximized measurement range. For a measurement resolution of ≅0.4 GHz, a measurement range of 0˜25 GHz is obtained for a CW microwave signal and a measurement range of 3˜18 GHz is achieved for a pulsed microwave signal. The system is potentially integratable in a monolithically chip, which have the desirable features of small size, low cost and stable operations.