How Much Do You Know About WDM Transponder?

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In optical fiber communications, a WDM transponder is a common element that sends and receives the optical signal from a fiber. Maybe you have seen and used it many times. But do you really know it clearly? How much do you know? Today, this article is going to talk about something about WDM (Wavelength Division Multiplexing) transponder.
What’s WDM Transponder?
WDM transponder, also named as fiber optic transponder, is an optical-electrical-optical (OEO) wavelength converter which is designed to perform an O-E-O operation to convert wavelengths of light. It plays a key role in WDM system, especially in DWDM (Dense Wavelength Division Multiplexing) system. Its name “transponder” is short for transmitter and responder, which clearly show its purpose. They are protocol and rate-transparent fiber media converters that support SFP, SFP+, XFP and QSFP transceivers with data rates up to 11.32 Gpbs. WDM transponders extend network distance by converting wavelengths (1310 to 1550nm), amplifying optical power and can support the “Three Rs” to Retime, Regenerate and Reshape the optical signals. In general, there is an O-E-O (optical-electrical-optical) function with this device. Fiber optic transponders and optical multiplexers are usually present in the terminal multiplexer.
How does the WDM Transponder work?
The most distinguished characteristic of WDM transponder is that it can automatically receive, amplify, and then retransmit a signal on a different wavelength without altering the data/signal content. In today’s commercial networks, wavelength conversion is only realized with optical to electronic to optical (O-E-O) transponders. OEO Transponder works as a regenerator which converts an optical input signal into electrical form, generates a logical copy of an input signal with a new amplitude and shape of its electrical pulses and uses this signal to drive a transmitter to generate an optical signal at the new wavelength. Here is a picture showing how a transponder works. From left to right, the transponder receives an optical bit stream operating at one particular wavelength (1310 nm). And then it converts the operating wavelength of the incoming bitstream to an ITU-compliant wavelength and transmits its output into a DWDM system. On the receive side (right to left), the process is reversed. The transponder receives an ITU-compliant bit stream and converts the signals back to the wavelength used by the client device.
What’s the Major Functions of WDM Transponder?
WDM transponder is a vital element in optical communication. Usually, its major function includes:
Conversions between electrical and optical signals
Serialization and deserialization
Control and monitoring
Why WDM Transponder Is Needed in WDM System?
There are several reasons that we need wavelength-converting transponder. The first reason is that they can connect incompatible equipment. Such an example is the conversion of 1300nm carrying wavelength of optic networks. Another one is because we have different fiber optic networks with different providers and different criteria. Therefore, we need WDM transponder to traverse from one fiber network to another. WDM transponder helps us to reduce the number of wavelengths required.
How Many Applications of WDM Transponder Do You Know?
WDM transponders are widely used in a number of networks and applications. The following are their major applications.
Convert Multimode to Single-Mode Fiber
It’s known to us that multimode fiber is often used for short distance transmission while single-mode fiber is used for long distance transmission. In order to exceed the limitation of multimode fibers, mode conversion is needed in networks. As the following figure showing, two switches are connected by the WDM transponder which convert the multimode fibers to single-mode fibers.
Convert Dual Fiber to Single-Fiber
In this case, two dual fiber switches are connected with a single-fiber via two transponders. The single fiber uses 1310nm and 1550nm wavelengths over the same fiber strand in opposite directions. As the following figure showing.
Wavelengths Conversion
The most common application of WDM transponder is wavelengths conversion. Fiber optic communications equipment with fixed fiber interfaces (ST, SC, LC or MTRJ connectors) operating over legacy wavelengths (850nm, 1310nm, 1550nm) must be converted to CWDM wavelengths with a transponder. In this application, the transponder is called WDM transponder or wavelength-converting transponder.
In addition, WDM transponder also can be used to extend 10G OTN network distances, SONET ring distances and provide a standard line interface for multiple protocols through replaceable 10G small form-factor pluggable (XFP) client-side optics.
With its own special features, WDM transponder facilitates a wide application in optical networks. Fiberstore provides a number of choices for OEO WDM transponder which have high performance and good quality. Here you can find different transmission rates of this products such as 2.5G, 4.25G, 8G, 10G and 40G, and different ports of OEO converters such as SFP+ to SFP+, SFP+ to XFP, XFP to XFP, etc. If you want to know more, please visit fiber-mart.COM.

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