Waveguide Bragg Grating for Fault Localization in PON

Femtosecond laser direct inscription is a technique especially useful for prototyping purposes due to its distinctive advantages such as high fabrication accuracy,true 3D processing flexibility,and no need for mold or photomask.In this paper,we demonstrate the design and fabrication of a planar lightwave circuit(PLC)power splitter encoded with waveguide Bragg gratings(WBG)using a femtosecond laser inscription technique for passive optical network(PON)fault localization application.Both the reflected wavelengths and intervals of WBGs can be conveniently tuned.In the experiment,we succeeded in directly inscribing WBGs in 1×4 PLC splitter chips with a wavelength interval of about 4 nm and an adjustable reflectivity of up to 70% in the C-band.The proposed method is suitable for the prototyping of a PLC splitter encoded with WBG for PON fault localization applications.

A Distributed Acoustic Sensing System for Vibration Detection and Classification in Railways

A distributed acoustic sensing(DAS)system is proposed and a data processing method for vibration is designed in this paper.The proposed DAS system is based on the Rayleigh scattering signal and utilizes phase-sensitive optical time-domain reflectometry(φ-OTDR)to demodulate the environmental vibration.It can collect the vibration information in railways and implement vibration classification based on the feature of sensed vibration signals.This system has been deployed in Guangzhou Shenzhen High-Speed Railway,and the experimental results validate its effectiveness.

Higher Speed Passive Optical Networks for Low Latency Services

Latency sensitive services have attracted much attention lately and imposedstringent requirements on the access network design. Passive optical networks (PONs) providea potential long-term solution for the underlying transport network supporting theseservices. This paper discusses latency limitations in PON and recent progress in PONstandardization to improve latency. Experimental results of a low latency PON system arepresented as a proof of concept.

Adaptability Analysis of Fluctuating Traffic for IP Switching and Optical Switching

The technological development of smart devices and Internet of Things(IoT)has brought ever-larger bandwidth and fluctuating traffic to existing networks.The analy⁃sis of network capital expenditure(CAPEX)is extremely important and plays a fundamen⁃tal role in further network optimizing.In this paper,an adaptability analysis is raised for IP switching and optical transport network(OTN)switching in CAPEX when the service bandwidth is fluctuating violently.This paper establishes a multi-layer network architec⁃ture through Clos network model and discusses impacts of maximum allowable blocking rate and service bandwidth standard deviation on CAPEX of IP network and OTN network to find CAPEX demarcation point in different situations.As simulation results show,when the bandwidth deviation mean rate is 0.3 and the maximum allowable blocking rate is 0.01,the hardware cost of OTN switching will exceed IP switching as the average band⁃width is greater than 6100 Mbit/s.When the service bandwidth fluctuation is severe,the hardware cost of OTN switching will increase and exceed IP switching as the single port rate is allowed in optical switching.The increasing of maximum allowable blocking rate can decrease hardware cost of OTN switching.Finally,it is found that Flex Ethernet(FlexE)can be used to decrease CAPEX of OTN switching greatly at this time.