We are quite familiar with difference between single-mode fiber (SMF) and multi-mode fiber (MMF), but we know little about single-mode and multi-mode transceiver. So what are they? And how to choose between them. Actually single-mode and multi-mode fiber are the transport media of a transceiver module. Besides this, here are certain things you need to know before making that decision which can prevent additional costs in the future.

The key differences between single-mode and multi-mode transceiver lie in the following expects—distance and cost, speed, how they work and compatibility issue. The following text will explain them one by one.

The cost difference between single-mode and multi-mode transceiver mainly arises from the cost difference between single-mode fiber and multi-mode fiber. It is known that the optic for single-mode is nearly twice the cost of multi-mode fiber. But the cost of a single-mode transceiver is negligible when installed as part of a project. Therefore, multi-mode transceivers are typically used when the distance involved is not long.

In contrast, multi-mode fiber has a much bigger core and uses a longer wavelength of light, resulting in MMF having higher numerical apertures which means they are better at collecting light than single-mode fibers. In fact, this refers to the optics is cheaper. Due to the modal dispersion in the fiber, multi-mode fiber has higher pulse spreading rates than single mode fiber, limiting multi-mode fiber’s information transmission capacity. Thus multi-mode transceiver can only support shorter distance.Figure 2 shows a compatible CiscoGLC-SX-MMDand a multi-mode patch cable.

We all knew that single-mode fiber and multi-mode fiber are not compatible. The main reason is that they possess distinct wavelength of the laser and core size of the fiber. Take Cisco SFP as an example, there is a type of SFP transceiver module (GLC-LX-SM-RGD) which can support both single-mode and multi-mode fiber. But amode conditioning patch cableis always required when using single-mode transceiver (likeGLC-ZX-SMD) with 62.5-micron MMF, and only at distances that would have worked using multi-mode transceivers. It does not work when we are exceeding the distance specified for multi-mode fiber. The result could be an elevated bit error rate.

Posted by: angelina at 02:50 AM | No Comments | Add Comment
Post contains 626 words, total size 7 kb.