Fig. 3: Measured Q-biased APL gain (set-up shown in Fig. 2).
From: Low-loss microwave photonics links using hollow core fibres
a Gain is plotted as a function of the optical power launched into the transmission fibre. The input signal has a frequency of 1 GHz. The measured gain with the SSMF transmission fibre is shown as a solid line with square symbols) and the measured gain with the HCF transmission fibre is shown as a solid line with circle symbols. The predicted gain considering a HCF transmission fibre with the lowest-published attenuation to date is shown as a dashed line. Dashed black arrows indicate net gain or loss. b Measured gain over the frequency range of 0–20 GHz obtained for the maximum received power as limited by SBS (SSMF APL) and photodiode (HCF APL). The HCF APL shows 15-dB higher gain than the SSMF APL
