Origin of high linearity in radio-over-fiber link with cascaded filter

Abstract

The radio-over fiber (RoF) transmission is a promising method for broadband signal transmission over long distances. For intensity modulated broadband signals, the fiber dispersion accumulated over long fiber can lead to power fading of the signal. The power fading drawback can be largely alleviated when optical single-side-band (OSSB) modulation approach is adopted, which had been demonstrated via different optical filter schemes [1][2]. However, the majority of these past filtering approaches also introduce additional distortions due to the filter response. We have recently proposed and demonstrated a novel yet practical approach of cascading four identical off-the-shelf 100 GHz optical bandpass Fabry-Perot filters into a fiber link, which not only minimizes the power fading effect, but also increases Carrier-to-Noise ratio and maintains the distortions at a low level [3]. In this paper the distortions are further characterized and compared between links using single filter and cascaded filter respectively, which provides insight on how the cascaded filter maintains the linearity while mitigates the power fading.