Side mode suppression and dispersion compensation analysis of a 60 GHz radio-over-fibre system based on a gain switched laser

The research and technical community have designated a band of 7 GHz between 57 and 64 GHz for short-range wireless communications. This paper utilizes a simple and cost effective technique for generating a 60 GHz millimeter-wave (mm-wave) signal using an optical comb source based on a gain-switched laser (GSL). This research investigates the effects unwanted comb lines have on the overall system performance with 2.5 Gb/s data transmission. To do this, a programmable optical filter is used to suppress the unwanted comb lines to varying levels. Bit-error rate (BER) measurements were carried out against received optical power to demonstrate the detrimental effects the unwanted comb lines have on the modulated mm-wave signal when not sufficiently suppressed. As chromatic dispersion is a limiting factor to the system's transmission distance, this work also investigates pre-compensation for dispersion utilizing the programmable group delay capabilities of the programmable optical filter, demonstrating the ability to extend the transmission distance by 12 km. All experimental results obtained are reinforced through simulation.