Coherent Optical Phase-Modulation Link

DSP based Coherent Receiver for Phase-Modulated Radio-over-Fiber Optical Links

“…When the digital PLL is locked, the frequency and phase difference between the transmitter and LO laser is removed from the complex signal Y. Next, we linearly demodulate the phase encoded RF signal, V in , through the relation Im[ln( )] [3]. The signal after linear demodulation is sent to feedforward carrier recovery to recover the RF carrier, whereafter the data can be recovered.…”

“…Radio-over-Fibre (RoF) optical links employing optical phase modulation at the antenna base station have recently attracted large attention [1][2][3]. An immediate advantage of optical phase modulation over intensity modulation is that the process of imposing a high radio frequency (RF) wireless signal on the optical carrier is inherently linear when conventional phase modulators are used.…”

“…With recent advances in integrated electronic circuits and digital signal processing, coherent receivers using DSP are becoming very attractive [5]. Recent efforts on digital coherent receivers for RoF optical links have mostly focused on analog communication with focus on linear demodulation [3]. Furthermore, in [3] no digital compensation technique was implemented for synchronizing the transmitter and the local oscillator (LO) laser.…”

“…Recent efforts on digital coherent receivers for RoF optical links have mostly focused on analog communication with focus on linear demodulation [3]. Furthermore, in [3] no digital compensation technique was implemented for synchronizing the transmitter and the local oscillator (LO) laser. In this paper, a novel DSP based coherent receiver for digital phase modulated RoF optical links is proposed, numerically investigated and experimentally demonstrated.…”

Radio-Frequency Transparent Demodulation for Broadband Hybrid Wireless-Optical Links

“…Recently, several photonic techniques for demodulation of -QAM signals have been proposed ( [4], [5] references therein), but they still require relatively complex high-bandwidth analog phase-locked-loop and RF components. Additionally, digital coherent receiver structures have also been proposed for RF-over-fiber links [6], [7]. Although, the demonstrated digital coherent techniques do not require electronic or optical phase-locked loops, they still require electronics such as analog-to-digital (A/D) converters or signal sources at high RF carrier frequencies [8].…”