Comparison of carrier suppressed and quadrature bias point external modulation for 40 GHz millimeter-wave photonic generation using a 16-QAM signal with directly modulated laser

A directly modulated laser usage is proposed for 16-QAM signal transmission over hybrid optical links using two optical frequency multiplication schemes based on external modulation for 40 GHz millimeter-wave (mmW) signal generation. We provide an experimental comparison of two possible approaches: quadrature bias point external modulation system using additional optical filter and null transmission point with suppressed carrier. The systems are discussed in terms of cost and complexity of mmW photonic transmission. High error vector magnitude performance of mmW transmission over fiber and free space optics links is demonstrated and an estimation of the sensitivity of the systems is provided.