Filter WDM device is a commonly heard item in the WDM fiber optic network solutions. Then what’s filter WDM or Filter Wavelength Division Multiplexer definition? Take this problem, this article will give a brief introduction of Filter WDM.

At the beginning, we need to know what WDM means. WDM or wavelength-division multiplexing refer to a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths of laser light. This technology is widely used in EDFA, Raman amplifiers, WDM networks and fiber optics instrumentation, applying to an optical carrier whereas frequency-division multiplexing typically applies to a radio carrier.

The Filter WDM or FWDM is a module based on environmentally stable TFF (Thin Film Filter) technology. FWDM filter combines or separates light at different wavelengths in a wide wavelength range, and offer very low insertion loss, low polarization dependence, high isolation and low temperature sensitivity and epoxy free optical path.

According to the different wavelength patterns, the WDM systems are devided into coarse CWDM, coarse wavelength-division multiplexing and DWDM, dense wavelength-division multiplexing. CWDM systems provide up to 8 channels in the 3rd transmission window (C-Band) of silica fibers around 1550 nm. DWDM uses the same transmission window but with denser channel spacing. WDM, DWDM and CWDM are based on the same concept of using multiple wavelengths of light on a single fiber, but differ in the spacing of the wavelengths, number of channels, and the ability to amplify the multiplexed signals in the optical space. EDFA provide an efficient wideband amplification for the C-band, Raman amplification adds a mechanism for amplification in the L-band. The C Band/L band filter wavelength division multiplexer is a micro optics device based on environmentally stable Thin Film Filters technology. It is used to combine or separate C band wavelength signals and L band wavelength signals in DWDM systems.

Basically, the FWDM Flitter series covers the following wavelength widows that widely used in optical fiber systems: 1310/1550nm for WDM or DWDM optical communications, 1480/1550nm for high-power DWDM optical amplifier/EDFA, 1510/1550nm for DWDM multi-channel optical networks, 980/1550nm for or high performance DWDM optical amplifier/EDFA and 1310/1490/1550nm for PON/FTTX/test instrument.