Photonic Generation of 60 GHz Millimeter-Wave by Frequency Quadrupling Based on a Mode-Locking SOA Fiber Ring Laser with a Low Modulation Depth MZM

Abstract

Generation and processing of millimeter-wave (MMW) signal based on photonic technologies is a new trend. A simple and effective optical technique to generate 60 GHz millimeter-wave signal by frequency quadrupling is proposed and demonstrated. In this approach, the frequency quadrupling efficiency is greatly improved by a semiconductor optical amplifier (SOA) fiber ring laser with 2nd-order rational harmonic mode-locking and a Mach-Zehnder modulator (MZM) which is biased at odd-order optical modulation side-bands suppressing state. A center-wavelength tunable comb filter outside the ring laser is tuned to select the optical sidebands separated by 60 GHz. The result shows that the power ratio between quadruple-frequency signal and double-frequency signal is improved at least 30 dB with the mode-locking ring laser when the modulation depth is less than 0.4 and the phase noise of the 60 GHz signal generated is better than –75 dBc/Hz at 1-kHz offset. The key advantage of the technique is that a high-frequency MMW signal can be generated with high efficiency by a low power microwave signal.