CWDM longd distance transmission solution

      1. Overview
      In the 40km to 80km medium and long distance fiber optic transmission applications, CWDM transmission system occupies a large market share, this paper briefly introduces the basics of CWDM and CWDM wavelength division multiplexer, focusing on the introduction of two typical CWDM long-distance transmission solutions.
      2. Introduction of CWDM Basics and WDM
      2.1 Introduction to CWDM Basics

Figure 1 1470-1610 8-channel CWDM channel wavelength diagram

      CWDM (Coarse Wavelength Division Multiplexing) Coarse Wavelength Division Multiplexing, ITU-T G.694.2 defines that CWDM has 18 wavelengths, respectively 1270, 1290 ..... .1610, channel spacing 20nm, channel bandwidth ± 6.5nm. Generally speaking, long distance transmission (more than 40km) uses the last 8 channels, the center wavelength are 1470, 1490..... 1610, CWDM optical module light-emitting wavelength requirements to control the center wavelength ± 6nm, to ensure that the wavelength of the module in the channel pass bandwidth.
      2.2 Coarse Wavelength Division Multiplexer Introduction

Figure 2 Moduletek 1U chassis 8CH CWDM MUX&DEMUX product photo

      8CH CWDM MUX&DEMUX Technical Parameters :
      Model: MT2010-CWDM-MUX8-A
      Wavelength : 1470-1610
      Channel spacing : 20nm
      Bandwidth: ±6.5nm
      Insertion loss : ≤2.5dBm
      Adjacent channel isolation : ≥30dB
      Non-adjacent channel isolation: ≥40dB
      Fiber Type: Dual Fiber
      Chassis: 19-inch 1U chassis
      Operating temperature: -5°C ~ +75°C
      3. CWDM Long Distance Transmission Network Solution
      3.1 2-site Networking
      Customer requirements:
      Node requirements, link length 60km, 8x10Gbps bandwidth communication between 2 sites is required.
      Program design:
      1. After calculation, the loss of MUX and total fiber ≤ 20dB, the link does not need optical amplifiers, and the direct use of CWDM WDM transmission scheme can provide a cost-optimal solution.
      2. Add 8CH WDM (MUX & DEMUX) on 2 nodes respectively, and the combined waveform needs to transmit 8-channel signals.
Program diagram:

Figure 3 2-node 60km CWDM WDM transmission solution diagram

      3.2 Multi-site Networking
      Customer Requirements
Node requirement: the link is 55km long, two nodes need to be added at 15km and 40km, and four sites can communicate with each other.
      Program design
      1. After calculation, the loss of MUX, OADM and total fiber is ≤20dB, no optical amplifier is needed for the link, and CWDM WDM transmission scheme can provide a cost-optimized solution. 2.
      2. 1CH OADM is added to the intermediate node to download and upload signals respectively.
      Scheme diagram:

Figure 4 4-node 55km CWDM WDM transmission solution diagram

      Moduletek limited provides the products involved in the above application guide.
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