Carrier Assisted Differential Detection With Generalized and Simplified Receiver Structure

• Published in: Journal of lightwave technology Vol. 39; no. 22; pp. 7159 - 7167
• Main Authors: Ji, Honglin, Dong, Shuangyu, Xu, Zhaopeng, Li, Jingchi, Unnithan, Ranjith Rajasekharan, Su, Yikai, Shieh, William
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.11.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Analog to digital converters; Carrier assisted differential detection; Coherence; complex-valued double-sideband signal; Complexity; direct detection; Iterative algorithms; Modulation; optical field recovery; Optical filters; Optical imaging; Optical interferometry; Optical receivers; Performance assessment; Receivers; Recovery; self-coherent homodyne detection; short-reach optical communications
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2021.3114235

Coherent detection has the primary advantage of optical field recovery, which enables channel impairment compensation and advanced modulation formats for high-capacity transmission. On the other hand, direct detection (DD) is more cost-effective due to its local oscillator (LO)-free detection. To gain the field recovery advantage while preserving the LO-free detection for DD-based receivers, carrier assisted differential detection (CADD) has been proposed to retrieve the complex-valued double-sideband (DSB) signal. In this paper, to extend the concept of CADD, we propose a simplified CADD scheme with reduced hardware complexity and present signal-to-signal beating interference (SSBI) iterative mitigation algorithms with and without symbol decision. The required number of photodetectors and analog-digital converters (ADCs) for the simplified CADD receiver becomes the same as the coherent homodyne counterpart but without needing the expensive narrow-linewidth LOs. The performance of the proposed simplified CADD receiver is evaluated by 60-Gbaud 16-QAM DSB signals. Extensive performance comparisons are made between (i) the generalized CADD receivers with and without the simplified receiver structure, (ii) SSBI iterative mitigation algorithm with and without the symbol decision, and (iii) single carrier (SC) and OFDM-modulated DSB signals for the simplified CADD receiver.