Simultaneous all-optical transparent phase multiplexing/de-multiplexing based on FWM in a HNLF

We propose and experimentally demonstrate a novel bidirectional modulation format converter that can simultaneously phase multiplex and de-multiplex PSK signals between QPSK and BPSK formats all-optically by employing four-wave mixing (FWM) in a single HNLF.

1. Introduction

Optical networks are typically classified in a multi-level hierarchy, such as core, metropolitan, and local access networks, depending on their size, bandwidth requirement and transmission distances. Since different networks may employ distinct modulation formats, to achieve transparent connection and enhance the network interoperability, all-optical modulation format conversion has been regarded as an important technology at the gateways between different communication networks. However, the network complexity and implementation costs are almost proportional to the numbers of employed electrical or optical format converters. Hence, for the next generation transparent communication networks, it is highly desirable to develop an all-optical modulation format converter that can simultaneously provide multiple format conversion functions in the optical layer [1].