Abstract

Coherent optical transmission systems offer enhanced possibilities concerning multilevel modulation and the electronic compensation of transmission impairments. One of the key components in a homodyne in-phase/quadrature (IQ) receiver is a 2 × 4 90° hybrid. However, this component is only commercially available in a form that requires an additional active control loop. This paper presents the different possible alternatives for the realization of the 2 × 4 90° hybrids and discusses their availability and properties, as well as the practical implementation considerations.

© 2006 IEEE

Compact optical 90° hybrid employing a tapered 2×4 MMI coupler serially connected by a 2×2 MMI coupler

Seok-Hwan Jeong and Ken Morito
Opt. Express 18(5) 4275-4288 (2010)

Coherent detection in optical fiber systems

Ezra Ip, Alan Pak Tao Lau, Daniel J. F. Barros, and Joseph M. Kahn
Opt. Express 16(2) 753-791 (2008)

Ultra-compact optical 90° hybrid based on a wedge-shaped 2 × 4 MMI coupler and a 2 × 2 MMI coupler in silicon-on-insulator

Wei Yang, Mei Yin, Yanping Li, Xingjun Wang, and Ziyu Wang
Opt. Express 21(23) 28423-28431 (2013)

All-fiber 90° optical hybrid for coherent communications

Leonid G. Kazovsky, Lyn Curtis, William C. Young, and Nim K. Cheung
Appl. Opt. 26(3) 437-439 (1987)

Compact optical 90° hybrid based on a wedge-shaped 2 × 4 MMI coupler and a 2 × 2 MMI coupler on a thin-film lithium niobate platform

Yake Chen, Xiaojun Xie, Yang Sun, Wei Pan, and Lianshan Yan
Opt. Lett. 49(5) 1145-1148 (2024)