PASSIVE MUX

The multiplexer does not use any power and has no software or firmware;  it’s a passive device which only “filters” the specific light emitted by the pluggable optic.  So in the case of CWDM, there are 18 different wavelengths of optics which have a specific color.  In the case of DWDM, there are about 48 channels which are commonly used in the industry.   We also offer DWDM ‘tunable’ optics, which can be programmed/tuned to send a specific light color as needed and are useful to have for spares.

For CWDM the nanometer or “color” of the light is commonly used in the naming.  There are two naming conventions – the official naming is 1611nm/1591nm/1571nm/1551nm, etc.  Many of the Switch/Router manufacturers such as Cisco use 1610nm/1590nm/1570nm/1550nm.  Technically there is no difference and you can easily use a 1610 optic in the 1611 port on a mux as each CWDM band is 15nm wide with the 1611nm as the center. For DWDM, different naming conventions are used – the most common being the Channels of the C-Band 100Ghz Grid.  Some vendors use Ghz and some prefer using nanometers.  For example, 1550.12nm is the equivalent to ‘Channel 34.’

The communication signals can have speeds ranging from 1G, 10G, 40G and 100G.  Since the introduction of this technology, 1G and 10G have been the most commonly used speeds and 40G and 100G are the newest speeds.  Since a multiplexer is simply filtering light, you can mix different speeds on the same multiplexer.

It is important to note that every multiplexer blocks a small percentage of the signal which comes through it.  This is know as the’ insertion loss’ (IL), which is calculated in dBs per channel and increases with the number of channels.  A MUX of good quality will cause less attenuation than a MUX of poor quality.  As an example, the typical loss of an 8 port mux is around 2dB.  For projects using the maximum power budget, Solid Optics offers ultra-low loss muxes.

Another important quality aspect of a mux is the ‘Channel Isolation’ which is the blocking of light between the channels, which should be at least 30dB.  At any lower value, light from neighboring channels can interfere with one another. Solid Optics has over a decade of experience in CWDM & DWDM dark fiber project design.  Please contact us with your details so we can help guide you to the best solution for your needs.