All About Dense Wave Division Multiplexing (DWDM)

The Dense Wave Multiplexing DWDM channel or light wavelength matrix (please see chart below) has brought tremendous benefit to the metropolitan and long haul data transmission world. Bandwidth hungry applications are requiring more information over the same transport infrastructure with the explosive growth of the internet.  With CWDM and DWDM Optics, the carrying capacity of the physical medium (fiber)  is increased because  each  DWDM/CWDM channel is transmitted at a different frequency.  Many engineers refer to this as the ‘rainbow’ of light, where each channels represents a color of light available within or over the medium (fiber). DWDM also has the ability to amplify all the wavelengths at the same moment, without first having to convert them to electrical signals, as well as the ability to carry signals of different speeds and types simultaneously over the medium (fiber).  This is called protocol and bit rate independence. DWDM is a big winner in the Metropolitan backbone.  It is fast and flexible in the provisioning of protocol- and bit rate-transparent, data centric, protected services, and has the ability to offer new and higher speed services at less cost. The key requirements for DWDM systems in the Metropolitan area include:  Multi-protocol support, cost effectiveness, reliability and availability, openness (interfaces, network management, standard fiber types, electromagnetic compatibility, ease of installation and management, size and power consumption, and scalability. Overall, the technical advantages to DWDM (Bandwidth Aside) are: DYNAMIC PROVISIONING (Provides engineers the ability to provision in days, not months, because of its fast and simple connections), SCALABILITY (DWDM leverages the available dark fiber to  meet the demand for capacity on point to point links and existing SONET/SDH rings), and TRANSPARANCY (It can transparently support TDM and data formats such as Gigabit Ethernet, ATM, ESCON, and fiber channel wit open interfaces over a common physical layer. DWDM enables a large savings on regenerators (RPTR) and amplifier infrastructure compared to the typical SONET/SDH optical networks, greatly reducing up front infrastructure cost barriers.   Besides the lowered infrastructure cost benefit, the DWDM systems have simplified the of network capacity by problem in many ways. Dense Wavelength Division Multiplexing (DWDM) ITU Grid: C-Band, 100 GHz Spacing Channel Frequency Wavelength Channel Frequency Wavelength (#) (GHz) (nm) (#) (GHz) (nm) 1 190100 1577.03 37 193700 1547.72 2 190200 1576.20 38 193800 1546.92 3 190300 1575.37 39 193900 1546.12 4 190400 1574.54 40 194000 1545.32 5 190500 1573.71 41 194100 1544.53 6 190600 1572.89 42 194200 1543.73 7 190700 1572.06 43 194300 1542.94 8 190800 1571.24 44 194400 1542.14 9 190900 1570.42 45 194500 1541.35 10 191000 1569.59 46 194600 1540.56 11 191100 1568.11 47 194700 1539.77 12 191200 1567.95 48 194800 1538.98 13 191300 1567.13 49 194900 1538.19 14 191400 1566.31 50 195000 1537.40 15 191500 1565.50 51 195100 1536.61 16 191600 1564.68 52 195200 1535.82 17 191700 1563.86 53 195300 1535.04 18 191800 1563.05 54 195400 1534.25 19 191900 1562.23 55 195500 1533.47 20 192000 1561.42 56 195600 1532.68 21 192100 1560.61 57 195700 1531.90 22 192200 1559.79 58 195800 1531.12 23 192300 1558.98 59 195900 1530.33 24 192400 1558.17 60 196000 1529.55 25 192500 1557.36 61 196100 1528.77 26 192600 1556.56 62 196200 1527.99 27 192700 1555.75 63 196300 1527.22 28 192800 1554.94 64 196400 1526.44 29 192900 1554.13 65 196500 1525.66 30 193000 1553.33 66 196600 1524.89 31 193100 1552.52 67 196700 1524.11 32 193200 1551.72 68 196800 1523.34 33 193300 1550.92 69 196900 1522.56 34 193400 1550.12 70 197000 1521.79 35 193500 1549.32 71 197100 1521.02 36 193600 1548.52 72 197200 1520.25 Note: for 200GHz spacing use either odd or even numbered channels.