A Photonic Phased Array Using Frequency Quadrupling without Optical Filtering

This work demonstrates a millimeter-wave photonic phased array where the input millimeter-wave is generated by a frequency quadrupling technique. The array consists of an external dual-parallel Mach-Zehnder modulator (DPMZM), an optical amplifier and a wavelength-division-multiplex (WDM) coupler. A wavelength-division-multiplexed optical signal from multiple lasers is inputted into the DPMZM and modulated with a 15-GHz radio-frequency (RF) signal to produce a 60-GHz modulation, in which more than 20 dB on optical harmonic distortion suppression ratio is realized without optical filtering. The modulated signal is propagated over an optical fiber is then divided into each feeder of the array by the WDM coupler and de-modulated by photo diodes. This system provides sufficient phase difference without distortion effected by chromatic dispersion of the fiber. The phases are controlled by changing the wavelength of the lasers. A beam shift from -30 degree to 30 degree is achieved by using this system.