Asymmetric Self-Coherent Detection Based on Mach-Zehnder Interferometers

Abstract

We propose an asymmetric self-coherent detection scheme (ASCD) based on Mach-Zehnder interferometers (MZI) for the field reconstruction of self-coherent (SC) complex doublesideband (DSB) signals. The MZI-ASCD scheme approaches the high electrical spectral efficiency (ESE) of homodyne coherent detection via a direct detection (DD) receiver having only two photodiodes (PD) and two analog-to-digital converters. The incoming SC-DSB signal is split into two parts at the receiver in this approach, one of which is delayed and beats with the other part at the outputs of an MZI. We show that the field reconstruction can be performed from the two tributaries of photocurrents. In addition, we present a modified MZI-ASCD scheme referred to as AUX-ASCD which introduces an auxiliary DD branch to improve the SNR of the detected signal. It is found that both the MZI-ASCD scheme and the AUX-ASCD scheme achieve higher OSNR sensitivity compared to the Kramers-Kronig scheme and in the meantime increases the ESE by a factor of 2 using a cost-effective DD receiver. These advantages make the ASCD scheme attractive for short-reach optical communications including edge cloud connections and mobile X-haul systems.

Design and Performance Investigation of Intensity Modulation/Direct Detection Scheme for C- and O-band Point-to-Multipoint Optical Networks

“…Secondly, DD needs one single-end photodiode (PD) and one analog-todigital converter (ADC) [29][30][31]. In contrast, coherent receiver requires complex hardware including local laser (to act as a local oscillator and should be synchronized with the transmitter laser), balanced PDs, and more than one ADC [32,33].…”

Digital subcarrier multiplexing-enabled carrier-free phase-retrieval receiver

“…To bridge the gap between direct and coherent detection via combining the high-performance coherent transmission and the cost-effective direct detection, several self-coherent receivers have attracted worldwide research interest, such as the Kramers-Kronig (KK) receiver, 4,5 the carrier-assisted differential detection (CADD) receiver, 6,7 and the asymmetric self-coherent detection (ASCD) receiver. 8 Those self-coherent receivers utilize an additional continuous-wave (CW) optical carrier to co-propagate with the modulated optical signal at the transmitter side (Tx). Consequently, the optical field of modulation signals can be reconstructed from the term of carrier-signal beating after direct detection.…”

“…Unfortunately, the loss of phase information is the major hurdle for direct detection, leading to an SSMF reach constraint for the high-speed intensity modulation direct detection (IM-DD) transmission. To bridge the gap between direct and coherent detection via combining the high-performance coherent transmission and the cost-effective direct detection, several self-coherent receivers have attracted worldwide research interest, such as the Kramers–Kronig (KK) receiver, 4 , 5 the carrier-assisted differential detection (CADD) receiver, 6 , 7 and the asymmetric self-coherent detection (ASCD) receiver 8 . Those self-coherent receivers utilize an additional continuous-wave (CW) optical carrier to co-propagate with the modulated optical signal at the transmitter side (Tx).…”

Asymmetric simplified coherent receiver based on twin-single-sideband signal realizes ultra-low computational complexity

“…To reduce the requirement of high-performance OBPF, the multiple-input and multiple-output adaptive equalization (MIMO-AEQ) algorithm is proposed to eliminate the cross-talk, 19 and the paper also points out that the system performance is better when the number of digital filter taps in the MIMO-AEQ reaches 25. Recently, an asymmetric direct detection (ADD) receiver for receiving twin-SSB (TSSB) signals is proposed, 20 – 23 which requires only one OBPF. The advantage of this approach is that one OBPF is eliminated and the system cost is reduced.…”