Hybrid twdm-pon system with downlink dpsk modulation and uplink direct modulation

Abstract

The invention provides a hybrid TWDM-PON system of downlink differential phase shift keying (DPSK) modulation and uplink direct modulation. The system comprises an optical line terminal, a feed line type optical fiber and a passive optical network system. The passive optical network system includes a remote node, distributed optical fibers and optical network units (ONU). The optical line terminal is connected to the remote node via the feed line type optical fiber, and the remote node is connected to the optical network units via the distributed optical fibers. According to the system, the downlink adopts DPSK modulation signals to improve downlink dispersion tolerance, and the uplink uses a direct modulation laser with tunable wavelength as an emitter, and thus a high-speed emission module of the ONU is realized at a low cost. Meanwhile, a periodic filter is disposed in each ONU to realize the demodulation of the downlink signal DPSK and the chirp management of the uplink signals, and thus the system cost is reduced, the dispersion tolerance of the PON system is improved, and the transmission distance of the system is increased. The hybrid TWDM-PON system is easy to realize, and can be completely compatible with a PON system based on time division multiplexing.

Description

technical field [0001] The invention relates to the technical field of optical communication, in particular, to a passive optical network transmission system based on periodic filters to realize low-cost, high dispersion tolerance hybrid wavelength division and time division multiplexing. Background technique [0002] With the emergence of a large number of new services, such as ultra-high-definition HDTV TV, large file sharing, cloud storage, social networking, etc., end users have higher and higher requirements for the uplink and downlink bandwidth of the access network. The system cannot meet future user needs. Therefore, in order to further improve the transmission capability of the access network system and meet the bandwidth requirements of longer-term users. The standard trend of NG-PON2 formulated by IEEE and ITU-T FSAN, proposed to study a new type of PON system, and determined the passive optical network (TWDM-PON) of time division multiplexing and wavelength divi...

AI Technical Summary

Problems solved by technology

However, in the actual implementation of the TWDM-PON system for high-speed uplink and downlink transmission, there are the following problems that need to be solved urgently: first, the realization of low-cost, high-performance colorless optical network unit; Dispersion tolerance problem caused by the increase of transmission distance

In addition, the transmitter of the ONU (Optical Network Unit, Optical Network Unit) in this structure is composed of a laser and an external modulator, which increases the cost of the ONU transmitter

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