Nonlinearity Tolerant LUT-based Probabilistic Shaping for Extended-Reach Single-Span Links

Pavel Skvortcov, Ian Phillips, Wladek Forysiak, Toshiaki Koike-akino, Keisuke Kojima, Kieran Parsons, David S. Millar

Research output: Contribution to journalArticlepeer-review


We propose Huffman-coded sphere shaping (HCSS) as a method for probabilistic constellation shaping which provides improved tolerance to fiber nonlinearities in single-span links. An implementation of this algorithm based on look-up-tables (LUTs) allows for low-complexity, multiplier-free shaping. The advantage of short-length shaping for mitigating fiber nonlinear impairments is experimentally demonstrated for a system employing dual–polarization 64–ary quadrature amplitude modulation (DP-64QAM) at 56 GBd and operating over 210 km of standard single-mode fiber (SSMF). A gain in achievable information rate (AIR) of 0.4 bits/4D-symbol compared with uniform signaling is measured, corresponding to a 100% improvement in shaping gain compared with ideal Maxwell–Boltzmann (MB) shaping. The combinatorial mapping and demapping algorithms can be implemented with integer addition and comparison operations only, utilizing an LUT with 100 kbit size.
Original languageEnglish
Article number9131860
Pages (from-to)967-970
Number of pages4
JournalIEEE Photonics Technology Letters
Issue number16
Early online date2 Jul 2020
Publication statusPublished - 15 Aug 2020

Bibliographical note

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.


  • Probabilistic shaping
  • experimental validation
  • multiplier-free LUT
  • nonlinear fiber channel
  • sphere shaping


Dive into the research topics of 'Nonlinearity Tolerant LUT-based Probabilistic Shaping for Extended-Reach Single-Span Links'. Together they form a unique fingerprint.

Cite this