IEC TR 61282-16:2022

Fibre optic communication system design guidelines - Part 16: Coherent receivers and transmitters with high-speed digital signal processing

IEC TR 61282-16:2022 is a technical report on coherent optical receiver and transmitter technologies that are employed in fibre optic communication systems as well as in optical test and measurement equipment. This document describes the principle of operation and functional capabilities of coherent optical receivers as well as the operation of optical transmitters used to generate complex vector-modulated signals. It is intended to serve as a technical foundation for other IEC documents and standards related to coherent optical transmission techniques.

General Information

• Status: Published
• Publication Date: 09-May-2022
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: SC 86C - Fibre optic systems and active devices
• Current Stage: PPUB - Publication issued
• Start Date: 13-Jun-2022
• Completion Date: 10-May-2022

Standards Content (Sample)

IEC TR 61282-16 ®
Edition 1.0 2022-05
TECHNICAL
REPORT
Fibre optic communication system design guidelines –
Part 16: Coherent receivers and transmitters with high-speed digital signal
processing
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IEC TR 61282-16 ®
Edition 1.0 2022-05
TECHNICAL
REPORT
Fibre optic communication system design guidelines –

Part 16: Coherent receivers and transmitters with high-speed digital signal

processing
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.01 ISBN 978-2-8322-0094-0

– 2 – IEC TR 61282-16:2022  IEC 2022
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms, definitions, and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 9
4 Background . 12
5 Coherent transmission of vector-modulated signals . 13
5.1 Typical receiver architecture . 13
5.2 Typical transmitter architecture . 14
5.3 Vector-modulated signals . 15
5.3.1 Mathematical description . 15
5.3.2 Binary amplitude and phase modulation . 16
5.3.3 Quadrature amplitude modulation . 17
5.3.4 Polarization multiplexing . 18
5.3.5 Higher-dimensional coding and constellation shaping . 18
6 Coherent receiver architectures and functional capabilities . 19
6.1 Basic principle of coherent detection . 19
6.1.1 General . 19
6.1.2 Homodyne and heterodyne detection . 19
6.1.3 Intradyne detection . 21
6.1.4 Polarization dependence . 21
6.1.5 Frequency dependence . 22
6.1.6 Phase and polarization diversity . 22
6.2 Single coherent mixer with balanced detection . 23
6.2.1 Principle of operation . 23
6.2.2 Common-mode rejection . 24
6.2.3 Polarization dependence . 26
6.2.4 Homodyne detection . 27
6.2.5 Heterodyne detection . 28
6.3 Dual coherent mixer with phase diversity . 29
6.3.1 Principle of operation . 29
6.3.2 Intradyne detection with frequency offset removal. 31
6.3.3 Compensation of chromatic dispersion. 33
6.3.4 Compensation of I-Q skew and phase offset . 40
6.3.5 Spectral shaping and frequency equalization . 42
6.4 Quadruple mixer with phase and polarization diversity . 46
6.4.1 Principle of operation . 46
6.4.2 Polarization demultiplexing . 48
6.4.3 Compensation of polarization-mode dispersion . 51
6.4.4 Compensation of polarization-dependent loss and residual CD . 53
6.4.5 Carrier phase recovery . 54
6.4.6 Impact of laser phase noise . 55
6.5 High-resolution spectral analysis with coherent receivers . 62
6.5.1 Measurement methods . 62

6.5.2 Dual mixer with polarization diversity . 63
6.5.3 Examples of high-resolution spectral analysis . 64
7 Digital signal processing in coherent receivers . 66
7.1 Basic features of digital signal processing . 66
7.2 Real-time DSPs for fibre optic communication systems . 70
7.2.1 Basic functions . 70
7.2.2 Timing recovery . 71
7.2.3 Cycle slip detection . 71
7.2.4 Compensation of nonlinear transmission effects . 71
7.2.5 FEC decoding and performance monitoring . 72
7.3 Software-based DSPs for optical modulation analysers . 73
8 Transmitters for vector-modulated signals . 75
8.1 Generation of vector-modulated signals . 75
8.2 Single Mach-Zehnder modulator . 77
8.2.1 Principle of operation . 77
8.2.2 Modulator extinction ratio . 81
8.2.3 Adaptive bias control in Mach-Zehnder modulators . 83
8.3 Dual Mach-Zehnder modulators . 85
8.3.1 Quadrature-amplitude modulation . 85
8.3.2 Compensation of finite extinction ratio . 86
8.3.3 Adaptive control of I-Q phase . 87
8.4 Quadruple modulators for polarization-multiplexed signals . 91
9 Digital signal processing in transmitters for vector-modulated signals . 94
9.1 Pre-distortion of optical signals . 94
9.1.1 General . 94
9.1.2 Pre-compensation of linear transmitter impairments. 95
9.1.3 Determination of transmitter frequency response . 96
9.1.4 Determination of transmitter skew . 101
9.1.5 Pre-compensation of modulator nonlinearity . 103
9.2 Symbol mapper, FEC encoding and framing . 105
10 Implementation and typical performance specifications . 106
10.1 Coherent receiver . 106
10.1.1 Implementation . 106
10.1.2 Typical performance specifications . 107
10.2 Optical transmitter . 108
10.2.1 Implementation . 108
10.2.2 Typical performance specifications . 109
10.3 Integrated coherent receiver and transmitter . 111
10.4 Tuneable laser assemblies . 111
10.4.1 Implementation . 111
10.4.2 Typical performance specifications . 111
Bibliography . 113

Figure 1 – Coherent optical receiver . 13
Figure 2 – Optical transmitter for coherent transmission . 14
Figure 3 – Generation of vector modulated signals . 16
Figure 4 – Examples of modulation formats for coherent communication . 17
Figure 5 – Signal and local oscillator frequencies for homodyne detection . 20

– 4 – IEC TR 61282-16:2022  IEC 2022
Figure 6 – Signal and local oscillator frequencies for heterodyne detection . 20
Figure 7 – Electrical spectra of homodyne and heterodyne beat signals . 21
Figure 8 – Single balanced mixer for coherent reception . 24
Figure 9 – Balanced heterodyne mixer with electrical down-mixing . 28
Figure 10 – Dual coherent mixer with phase diversity . 30
Figure 11 – Intradyne beat spectrum with 2 GHz frequency offset . 32
Figure 12 – Differential phase shifts introduced by 3 000 ps/nm GVD .
...