Dear customers, due to the implementation of the GDPR policy in Europe, UTSOURCE has also made adjustment accordingly to meet the policy requirements. Please read the new privacy policy carefully and this window will no longer pop up after you accept it.

Agree Later 提交

SFP Module Optical Signal Strength

Author:Utoptical Date: 09/28/2018 SHARE

 SFP Module Optical Signal Strength


It is well-known that SFP optical modules use a range of applications including Fiber Channel (FC) switches, SONET / SDH networks, Gigabit Ethernet, high-speed computer links, CWDM and DWDM interfaces. While the SFP+ module and the switch are connected, the optical signal strength is an important parameter to make sure the normal operation of the whole connection. this article will focus on The optical signal strength of an SFP optical module.


Let’s start with the optical transceivers used. In the overwhelming majority of these systems, the SFP (Small Form-Factor Pluggable) module is the optical transceiver of choice, mainly due to its very small size, low cost, and the abundance of pre-existing technology readily available that was originally developed for the optical wireline industry (the fiber optic core backbone). It is easy to understand why the manufacturers of this new wireless system architecture selected SFP modules as the transceiver of choice.


The SFP optical module optical signal strength importance

In most cases, the signal strength of the SFP optical module covers Tx power and Rx power, Tx power means the transmit power signal, Rx power means the received power signal. the values of Tx and Rx power for SFP optical modules indicate that the SFP optical module is working properly within a specific range. For example, Cisco GLC-SX-MM optical module , the transmit power range from -9.5 to -3 dBm and the received power from 0 to 17 dBm. If Tx or Rx is within -30 dBm or less,then it indicates that no signal has been transmitted or received.


The strength of the optical signal directly can help determine whether the network connection is normal or not. If the Rx power is not strong, there will be no signal in the optical link. This is why the long distance optical module or optical amplifier needs to be used for long distance transmission. the SFP optical module will be damaged if the Rx power is too strong, so choosing a high-quality SFP optical module is to ensure that the network connection can be the basic guarantee of normal operation.


SFP optical module optical signal strength measurement

In general, You can find two common methods to measure the optical power strength: milliwatts (mW) and dBm, the former measuring the optical power strength by power, while the latter measuring the optical power strength by power value. Different vendors may use one of them to measure the power of the optical signal, for example, Cisco switch selected dBm to measure, and Brocade switches used to measure with mW.


mW->dBm:dBm=10*(Log mW)


To determine whether the SFP optical module (transmitter and receiver) operates at the appropriate signal level, you will be able to view the SFP optical module information, which is critical including fiber type, transmitter output power range and optical receive power range, etc.,

Other switches, such as Cisco and Brocade SAN switches, are available in the CLI (Command Line Interface), which is used to view detailed information about SFP optical modules, including rate, serial number, part number, and receive / send direction optical signals strength.



Although Cisco and Brocade measure the optical signal strength of different methods, they are supplied SFP optical module at the time of signal strength and useful optical signal strength range. As long as the signal strength of the SFP optical module is within the suitable range, the SFP optical module can operate normally.


If you are interested in UTOPTICAL full range of optical transceivers & cables ,please visit :UTOPTICAL Online Store.

Alternate Text

Please Iogin ? to participate in the comments New customer Start here.


no comment yet

Alternate Text