Microwave Photonic Signal Processing with Dynamic Reconfigurability

Abstract

An optical beamforming network that uses an uncooled Fabry-Perot laser is demonstrated. This is achieved by using a fast-scanning, high-resolution optical spectrum analyzer to track the frequency and power shift of the uncooled laser, and then reconfiguring a programmable Fourier-domain optical processor to provide compensation. In this way, the need for temperature control of the laser is eliminated, and the number of optical sources is reduced by using the output spectral lines of the laser. The system realizes six wideband microwave photonic phase shifters, and the resulting magnitude and phase responses vary within a 2σ deviation of 6.1dB and 14.8°, respectively, even when the laser current is changed during measurement. A microwave photonic filter is presented based on a feedback structure, which uses a Fourier-domain optical processor as the control element and the fast-scanning optical spectrum analyzer as the feedback component. This system provides low-pass RF response. Experimental results demonstrate a 6-tap microwave photonic filter with a free spectral range of 2.5GHz. The power fluctuation of the first-order passband in RF response is within ±1dB over 20 minutes. A novel tunable all-optical microwave photonic mixer is presented based on serial phase modulation and an on-chip notch filter. The notch filter breaks the out-of-phase symmetry between the upper and lower sidebands generated from phase modulation, resulting in bandpass response of frequency selection. This system is achieved through an all-optical approach, which does not require electrical components, thus increasing the operation bandwidth of the system. The tunability of frequency selection is achieved through adjusting the wavelength of the optical source. Experimental results verify the technique with a 3rd-order SFDR of 91.7dBm/Hz2/3.