Before we discuss anything, you need to understand what DWDM technology is. Dense Wavelength Division Multiplexing or DWDM combines a set of optical wavelengths, transmitting with one fiber. As a laser technology, DWDM increases bandwidth on existing fiber-optic backbones. Most importantly, DWDM technology enables optic fiber networks to transmit signals of several wavelengths simultaneously.
The DWDM system has two indispensable modules; Mux and Demux. Together it’s referred to as DWDM Mux/Demux. Mux is at the transmitter end, bringing several data signals together for transporting over a single fiber. On the other hand, Demux, at the receiver end, separates the signals coming together and passing each channel to an optical receiver.
When combined, the DWDM Mux/Demux multiplexes multiple DWDM channels into one or two fibers, extending the bandwidth of optical communication networks with low cost and long transmission distance. This is what a ideal solution of the model is.
About Active/Passive DWDM Mux?Demux
Based on the device’s need for power supply, the DWDM is divided into active DWDM Mux/Demux and passive DWDM Mux/Demux. If it’s active DWDM Mux/Demux, it means the device needs a power supply.
Difference
An active DWDM Mux/Demux consists of a wavelength adjustable laser, wavelength-adjustable filter, wavelength-selective amplifier, etc. With this, you get more control over your optical network. The best part is that you can dynamically re-tune wavelengths without dropping connections. Commonly, the active DWDM Mux/Demux is used in large-capacity optical transmission applications.
On the other hand, passive DWDM Mux/Demux is unpowered, pure optical equipment. Unlike active DWDM Mux/Demux, the passive DWDM Mux/Demux requires zero maintenance, upgrades, or electricity to function properly. It consists of a dispersion device, interference device, optical coupler, etc. Comparatively, passive DWDM Mux/Demux is simple and convenient to use as it is a plug-and-play system, which is mainly applied to the access layer of MAN, campus network, enterprise network as well as various special industry networks, including banking, public, security, etc. In the present situation, it’s widely used in optical fiber communication solutions.
The only thing is that passive DWDM Mux/Demux doesn’t have OAM, meaning there is no protection in case of link failure. But, fortunately, there is another type of DWDM Mux/Demux to solve this problem.
This type adds optical switches, optical splitters, and other devices in an optical fiber link based on the passive DWDM Mux/Demux. When power is ON, the third type is used as an active DWDM Mux/Demux to monitor each port in real-time. On the other hand, when the power is off, the device is used as a passive DWDM Mux/Demux without affecting the link transmission. In simple words, the third type combines the advantages of active and passive DWDM Mux/Demux, solving the shortcomings of the passive option. No matter what, it’s difficult to manage and maintain this problem through the intervention of active equipment.
This is how active and passive DWDM Mux/Demux is different. When you buy them, keep this difference in your mind.