A passive multiplexer in most networks consists of a mux and demux optical component. The mux combines, or multiplexes, wavelengths onto a fiber. The demux on the other end of the connection splits, or de-multiplexes, the connections.
In DWDM system, DWDM mux demux is two indispensable modules. Mux (Multiplexer) is a module at the transmitter end that brings several data signals together for transporting over a single fiber, while Demux (Demultiplexer) is a module at the receiver end that separates the signals that come together and passes each channel to an optical receiver.

CWDM mux demux (Coarse Wavelength Division Multiplexer/Demultiplexer) is a flexible, low-cost solution that enables the expansion of existing fiber capacity. CWDM multiplexer is for combining signals together, while demultiplexer is for splitting signals apart.

A polarization-maintaining (PM) WDM filter is a small device used to multiplex PM signals while maintaining the output polarization. When you are using highly efficient systems, PM fibers and PM signals play a very critical role in ensuring the desired efficiency.

Fiber Patch Cord & Cable Assembly, often called fiber patch cable, fiber jumper, or fiber patch lead, is a length of fiber cable that terminated with fiber optic connectors (LC, SC, MTRJ, ST and etc.) at each end. The connectors allow fiber optic patch cord to be rapidly connected to an optical switch or other telecommunications/computer device.

Fiber loopback is widely used for various applications. In terms of telecommunication, loopback is a hardware or software method to feed a received signal or data back to the sender. It is very useful for solving physical connection problems.

Fiber terminators(Plug-in type or Build-out type) are used to terminate unused fiber connector ports in fiber optic systems so optical terminators unwanted reflections are not introduced back into the system. It is used in the fiber-optic networks to install on possibly unused ports.

Fiber optic isolator is a passive component used for fiber optic communications. As a magneto-optic device, the purpose of optical isolator is to allow light to be transmitted in only one direction. An optical isolator is a device that is designed to allow the optical signal travel in the forward direction while block reflections that would travel in the backward direction. Optical isolators are critically important in many applications in optical systems.

FBT splitter(fused biconical taper) is the traditional technology in which two fibers are placed closely together, typically twisted around each other and fused together by applying heat while the assembly is being elongated and tapered. A signal source controls the desired coupling ratio. The fused fibers are protected by a glass substrate and then protected by a stainless steel tube, typically 3 mm diameter by 54 mm long. FBT splitters are widely accepted and used in passive optical networks.

The PLC splitters are used to separate or combine optical signals. A PLC (planar lightwave circuit) is a micro-optical component based on planar lightwave circuit technology and provides a low-cost light distribution solution with small form factor and high reliability. PLCs are manufactured using silica glass waveguide circuits that are aligned with a v-groove fiber array chip that uses ribbon fiber. Once everything is aligned and bonded, it is then packaged inside a miniature housing. PLC splitters have high quality performance, such as low insertion loss, low PDL, high return loss, etc.http://www.arkoptics.com/passive-multiplexer/