Multi-channel crosstalk in a 25-GHz spaced DWDM millimeter-wave-band radio-over-fiber system

In this paper, we experimentally investigate the influence of multi-channel optical crosstalk in a 25-GHz spaced dense-wavelength division multiplexing (DWDM) millimeter-wave-band radio-over-fiber (RoF) downlink system. The eleven-channel crosstalk filtered with arrayed waveguide gratings (AWGs) was intentionally mixed with the desired channel of the RoF signal. We defined the suppression ratio of the crosstalk as the ratio of the mm-wave power of the desired channel and undesired channels which are estimated from optical spectrum of the detected RoF signal. The experimental results show that the power penalty due to the crosstalk of less than 1 dB is obtained when the suppression ratio is more than 25 dB.