Gezhi Photonics (Shenzhen) Technology Co., Ltd.

CWDM cost efficient transport in optical networks Coarse Wavelength Division Multiplexing (CWDM) is the technology of choice for cost efficiently transporting large amounts of data traffic in telecoms or enterprise networks. Optical networking and especially the use of CWDM technology has proven to be the most cost efficient way of addressing this requirement.   CWDM typically has the capability to transport up to 16 channels (wavelengths) in the spectrum grid from 1270 nm to 1610 nm with a 20 nm channel spacing. Each channel can operate at either 2.5, 4 or 10 Gbit/s. CWDM can not be amplified as most of the channels are outside the operating window of the Erbium Doped Fibre Amplifier (EDFA) used in Dense Wavelength Division Multiplexing (DWDM) systems. This results in a shorter overall system reach of approximately 100 kilometers. However, due to the broader channel spacing in CWDM, cheaper un-cooled lasers are used, giving a cost advantage over DWDM systems.   Transmode uses both CWDM and DWDM technologies as a means of transporting different types of services, e.g. Ethernet, SDH/SONET, and Fibre Channel (FC) in metro networks. CWDM is the most cost efficient of the two WDM variants, but has limitations in the distance over which the traffic is transported and in total channel count. With Transmode CWDM solutions, the distance supported is up to 100 km.   Both Transmode’s TM-Series and TS-Series product families are CWDM and DWDM agnostic. This means a CWDM network can initially be deployed with either product series and when required, the network can be simply upgraded to a hybrid CWDM/DWDM network using common cards and pluggable optics. Therefore, by deploying Transmode’s CWDMor DWDM based solutions the lowest possible day 1 cost are enabled without sacrificing the scalability of the network.

CWDM Passive System with active CWDM SFP transceiver CWDM passive system with the "point to point" topology is designed to organize the extraction and addition of optical signals at predetermined wavelengths from a communication line. There are several construction options for such systems: 1. Setting up communication between the head-end station and terminal nodes that are interconnected with single/dual fibers. The principal feature of this solution is to use of one "head"multiplexer (MUX) and several "terminal" add/drop multiplexers(OADM), which ensure the optical signal extraction at any path point. 2. Arranging a dual-sided system where two multiplexers (MUX) are connected with single/dual fibers. In this system, both single-sided and dual-sided add/drop multiplexers (OADM) providing transmission of signals in either direction are used. The maximum number of spurs is determined by the number of duplex transmission channels (2 to 18) and the optical line budget. OADM modulesused in these systems add optical signal attenuations, which lead to an overall reduction in the path length. In the systems under consideration, 18 transmission channels and 18 extraction points can be arranged as a maximum. CWDM systems can transport 18 wavelengths (1270~1610nm) with a channel spacing of 20nm. In custom application typically use 1470 to 1610nm in the spectrum grid. Compare with DWDM, CWDM has a wider channel spacing than DWDM. System Capabilities: Organization of up to 18 signal output points; Support of all transmission protocols; Transmission of any kind of traffic: data, voice, multimedia. Transmission Medium Features: Single/dual optical fibers; Maximum route length of up to 90 km (depending on the number of output points and fiber-inserted attenuations); Maximum value of fiber-inserted attenuations of about 30 dB (depending on the number of implemented channels).

DWDM Passive Systems GEZHI DWDM passive systems represent a logical extension of the CWDM technology.  Wavelength division multiplexing of DWDM 100 Ghz systems occurs in a narrow range of 1525 nm – 1565 nm, with a pitch of only 0.8 nm between adjacent channels. The channel capacity of such systems may reach 20 channels when working via a single fiber and 40 channels when working via dual fibers. A special feature of the DWDM passive system is the absence of any active components. The line functions only due to the optical budget of transceivers used. No optical signal amplifiers and dispersion compensators are used. DWDM passive systems have a high channel capacity and potential for expansion, however, the transmission distance is limited to the optical budget of transceivers used. The main application of DWDM passive systems is metro networks, as well as high-speed communication lines with a high channel capacity. Unlike active backbone networks with amplifiers and dispersion compensators, the passive DWDM allows to arrange a high-speed system having high channel capacity with substantial cost savings. GEZHI DWDM Link: https://www.gezhiphotonics.com/dwdm-100ghz-200ghz-50ghz.html   System Capabilities: Transmission of up to 40 duplex communication channels; Support of all transmission protocols; Transmission of any kind of traffic; Arrangement of metro networks with high channel capacity. Optical Medium Features: Single/dual optical fibers; Maximum route length of up to 70 km depending on the channel capacity.