What is channel spacing in WDM?

The functionality of DWDM (Dense Wavelength Division Multiplexing) resembles to the one of CWDM. The DWDM channel spacing is 0.8/0.4 nm (100 GHz/50 GHz grid). This small channel spacing allows to transmit simultaneously more information.

How much channel spacing is required for dense WDM DWDM?

Dense WDM (DWDM) uses the C-Band (1530 nm-1565 nm) transmission window but with denser channel spacing. Channel plans vary, but a typical DWDM system would use 40 channels at 100 GHz spacing or 80 channels with 50 GHz spacing. Some technologies are capable of 12.5 GHz spacing (sometimes called ultra-dense WDM).

Why the operating wavelength a λ 1.3 μm and b 1.55 μm are widely used for long distance optical fiber communication networks?

At around 1.3 – 1.5 micron, both Rayleigh scattering and IR absorption (shadow overtones) makes a valley region (minimum absorption), which is idea for long distance data transmission using silica fibers. Since optical communication reflects silica, this is much more established as the low loss window.

What is WDM channel?

Channeling data in WDM A WDM channel is therefore assigned to a specific frequency or wavelength within the optical frequency or wavelength domain that is sent through the optical fiber. Different WDM channels are separated by a defined difference in frequency or wavelength, which is the channel spacing.

Why WDM must be spaced properly?

Wavelengths in WDM must be properly spaced to avoid interchannel interference. Transmission bandwidths in 1310 nm and 1550 nm windows allow the use of many simultaneous channels for sources with narrow spectral widths. narrow portion of the transmission bandwidth capability of a fiber.

How is channel spacing calculated in DWDM?

Rmax =Bolog2(OSNR+1) For a 62 GHz channel passband (for standard 200 GHz DWDM channel spacing) and an OSNR of 126 (21 dB) the maximum possible channel capacity is 433 Gbps.

Why is it called 1310 and 1550?

Typically multi-mode glass fibers use light at 850 nm – 1300nm, referred to as “short wavelength” and single-mode fiber operates at 1310, or 1550 nm, called “long wavelength”. These wavelengths are used because they have the lowest attenuation rate.

What is the difference between 1310 and 1550?

If made properly, the cable assembly will test about the same at either 1310 or 1550. 1550 Insertion Loss results are generally better by a few hundredths of a dB, due to, in part, its lower fiber attenuation. It’s normal that Insertion Loss values for a connector be ~0.01 – 0.05 dB better at 1550 than 1310.

What is channel spacing in VHF?

By reducing the channel spacing between consecutive transmit frequencies in the aeronautical VHF bands, the 8.33 kHz channel spacing adds two additional channels for every 25 kHz channel. This is to overcome the frequency congestion in the medium to long term by providing more channels.