With the wide application of WDM (Wavelength Division Multiplexing) technology, a number of WDM optical networking products play a vital role in optical communication. WDM filter is part of them. Today, this article will give you a brief introduction to this optical component.
What Is WDM Filter?
WDM filter, also know as FWDM (Filter Wavelength Division Multiplexer), is based on environmentally stable Thin Film Filters (TFF) technology. Its function is to combine or separate light at different wavelengths in a wide wavelength range. Take 1310/1550nm WDM filter for example, this filter can transmit the channel of 1310 nm but reflect channel of 1550 nm. With these features, WDM filter is widely used in EDFA (Erbium Doped Fiber Amplifier), Raman amplifiers, WDM networks and fiber optics instrumentation. In addition, WDM filter has very low insertion loss, low polarization dependence, high isolation and excellent environmental stability.
Types & Application
According to the fibers that WDM filters apply, the WDM filter can be divided into single-mode WDM filter, multimode WDM filter and triplexer WDM filter.
Single-mode WDM Filter
Single-mode WDM filter can separate or combine two wavelength windows. One is around 1310 nm and the other is around 1550 nm. The bandwidth of 1310nm and 1550nm channels can add or reduce 40 nm. That is to say, the wavelength range of single-mode WDM filter is from 1270 nm to 1350 nm and 1510 nm to 1590 nm. And as its name shows, they enable the bi-directional communication using one single fiber.
Here are two single-mode WDM filters. 1310/1550nm single-mode FWDM and 1480/1550nm FWDM (Pump WDM). The former one combines or separates 1310 nm and 1550 nm optical signals, used in single-mode fiber communication. And the latter FWDM separates or combines pump laser and optical signals, Which is usually used for C-band EDFA.
Multimode WDM Filter
Multimode WDM filter often separates or combines two wavelength windows. One is around 850 nm and the other is around 1310 nm. Distinct from single-mode WDM filter, the bandwidth of multimode WDM filter can plus or reduce 50 nm, filtered out from 800 nm to 900 nm and 1260 nm to 1360 nm wavelength range. And multimode WDM filter is usually used in multimode fiber communication, CATV and testing instrumentation. Following are some examples.
850/1310nm FWDM—This FWDM is used interference filter technology to separate or combine 850 nm and 1310 nm optical signals. And it is often used in multimode fiber communication, CATV (Community Antenna Television) and testing instrumentation.
1310/1550nm multimode FWDM—It is used interference filter technology to separate or combine 1310 nm and 1550 nm optical signals. It is also used in multimode fiber communication, CATV and testing instrumentation.
Triplexer WDM Filter
Triplexer WDM filters often can separate or combine more than two wavelengths. And they are often used in the existing triplex FTTH system. Here are some common types of triplexer WDM filter.
1310/1490/1550nm FWDM—This FWDM uses single fiber triple operation wavelength transmission technology. The 1550nm wavelength is used for downstream analog CATV; the 1310nm wavelength is used for the upstream transmission to a large number of end users; the 1490nm wavelength is used for digital downstream transmission. It is applied for PON, FTTX and test instrument.
1310/1550/1625nm FWDM—It enables non-intrusive testing of any fiber path on a remote fiber test system. With this capability, it is ideal for testing active fibers in service.
1310/1490/1550/1625nm FWDM—It is used to combine or separate 1625nm channel with three triplex wavelengths: 1310 nm, 1490 nm and 1550 nm. By using this device, 1625nm channel can be added into the existing triplex FTTH system.
In addition, except for the FWDMs mentioned above, here is another WDM filter—C Band/L Band WDM filter. This WDM filter can combine or separate C band wavelength signals and L band wavelength signals in DWDM systems. The common type of C Band/L Band FWDM is DWDM red/blue band filter.
FS.COM WDM Filter Solution
In order to meet our customers’ needs, Fiberstore provides reliable and high performance WDM filters. Of course, we also offer filter WDM modules that are customized to the particular wavelength bands for specific applications.
| Part Number | Description |
| FS-FWDM-T31/R55-9-SA-1 | FTTH/FTTx 1310/1490/1550nm FWDM Filter WDM for CATV |
| FS-FWDM-T55/R31-9-SA-1 | FTTH/FTTx 1310/1490/1550nm FWDM Filter WDM for CATV |
| FS-FWDM-T31/R4955-9-SA-1 | FTTH/FTTx 1310/1490/1550nm FWDM Filter WDM for CATV |
| FS-FWDM-T49/R3155-9-SA-1 | FTTH/FTTx 1310/1490/1550nm FWDM Filter WDM for CATV |
| FS-FWDM-T55/R3149-9-SA-1 | FTTH/FTTx 1310/1490/1550nm FWDM Filter WDM for CATV |
| FS-FWDM-T4955/R31-9-SA-1 | FTTH/FTTx 1310/1490/1550nm FWDM Filter WDM for CATV |
| FS-FWDM-T3149/R55-9-SA-1 | FTTH/FTTx 1310/1490/1550nm FWDM Filter WDM for CATV |
Conclusion
WDM filter can be widely used in system monitoring, fiber optical amplifiers, WDM networks and fiber optics instrumentation. As a professional and reliable fiber optic components manufacturer that always pursue excellent quality and high performance, FS.COM has been well recognized among our customers throughout the world. If you have any question, please contact at sales@fs.com.
