Single-photodiode per polarization receiver with signal-signal beat interference suppression through heterodyne detection

Abstract

We show that a simplified, single-photodiode per polarization heterodyne receiver is able to directly suppress signal-signal beat interference (SSBI), without the need for cancellation in the digital domain. We characterize performance degradation due to SSBI, and show that a strong LO in the receiver can mitigate SSBI. Transmission of 400 Gb/s-class signals is shown over single fiber spans of up to 160 km, and over field-deployed metropolitan area fiber. These results indicate that a single photodiode can be used to receive complex optical signals in high speed fiber systems without the need for SSBI cancellation in the digital domain.

Performance of Kramers–Kronig Receivers in the Presence of Local Oscillator Relative Intensity Noise

“…3 (b) presents the SNR with respect to LOSPR at different OSNRs for the receiver without the KK scheme. It can be observed that the increase in SNR with increasing LO power is much more gradual, although at high LOSPR values, effective SSBI suppression is achieved, as described in [17].…”

“…The simulations were carried out using MATLAB, with a single channel being considered. The system employed a 28 Gbaud PDM 16-QAM signal, at a gross data rate of 224 Gb/s, encoding a 2 17 de Bruijn binary sequence. Lasers used in the transmitter and receiver were centered at 1550 nm with a linewidth of 1 MHz (unless otherwise stated), typical for the low-cost DFB lasers used in short-reach systems.…”

“…The Kramers-Kronig (KK) scheme, in particular, has been demonstrated to be effective in reconstructing the optical phase from the received signal's envelope provided that the local oscillator-to-signal power ratio (LOSPR) is sufficiently high to satisfy the minimum phase condition [6,7,[9][10][11][12][13][14][15][16]. A third approach, investigated in [17], is to achieve linearization of the receiver without the requirement for additional DSP through the use of a sufficiently high LO power. In this case, the power of the unwanted signal-signal beating terms is negligible in T comparison to that of the desired signal-LO beating products.…”

Transmission Schemes for Future Access Networks

“…The use of heterodyne detection with a single photodiode has been investigated in [14]. This provides a saving of one photodiode, but results in signal-signal beating interference (SSBI), in contrast to the case with balanced detection.…”

“…This provides a saving of one photodiode, but results in signal-signal beating interference (SSBI), in contrast to the case with balanced detection. Solutions that have been proposed to overcome this include the use of a high LO-to-signal power ratio, so that the wanted signal-LO beat terms dominate over the signal-signal beat terms [14], and the use of digital signal processing (DSP) to mitigate the SSBI, e.g. the Kramers-Kronig scheme [15][16][17][18].…”