APT Small Class: -- Distinction and selection of CWDM, DWDM and CCWDM

When selecting WDM, DWDM and CCWDM, customers are often confused about CWDM, DWDM and CCWDM. What is the difference between these three products and how to choose them?

How does WDM work?

Wavelength division multiplexing (WDM) is the simultaneous transmission of several signals of different wavelengths coupled on a single optical fiber. It usually has a composite wave and a component wave. The main function of MUX is to combine multiple signal wavelengths in a single optical fiber at the sending end. The main function of DEMUX is to separate multiple wavelength signals transmitted in a single optical fiber at the receiving end. The main purpose of WDM is to increase the available bandwidth of optical fiber. As a result, WDM systems are widely used by telecommunications companies to expand capacity through WDM without the need to lay more fiber.

How to select CWDM and DWDM?

CWDM (Coarse Wavelength Division Multiplexer) is a sparse Wavelength Division Multiplexer, also known as Coarse Wavelength Division Multiplexer. DWDM (Dense Division Multiplexer) is a Dense WDM.

There is a big difference between CWDM and DWDM in the channel interval. Channel spacing is the difference between the nominal carrier frequencies of two adjacent channels and can be used to prevent inter-channel interference. The wavelength interval between CWDM channels is 20nm, while DWDM channel interval is 1.6/0.8/0.4nm (200GHz/100 GHz/50 GHz), which is much smaller than CWDM. Differences in channel spacing also lead to differences in the bandwidth and capacity that CWDM and DWDM can carry. DWDM module can further improve system bandwidth and capacity by using closely spaced wavelengths to carry more signals on the same optical fiber.

The biggest advantage of CWDM system is its low cost, which is mainly reflected in the filter and laser. The wide wavelength interval of 20nm also brings advantages of low technical requirements for the laser and simplified structure of the optical multiplexer/demultiplexer to CWDM. The structure is simplified, the yield is improved, so the cost is reduced. DWDM's cost increase is mainly due to the high cost of laser diodes and the cooling laser technology used to maintain wavelength stability.

What is CCWDM?

CCWDM is a mini WAVELENGTH division multiplexer and a mini version of CWDM. A TFF(thin film filter) based WDM technology works in the same way as CWDM. The difference is that CCWDM USES free space technology, and its package size is greatly reduced compared with CWDM module, and the insertion loss is lower and the consistency is better. It can replace CWDM products in telecommunications, enterprise networks, PON networks, cable TELEVISION and other fields.

When CWDM/DWDM/CCWDM scheme is selected, the optimal scheme should be made according to their respective characteristics and differences and the requirements and budget of application scenario construction should be considered comprehensively.

Qingdao APT is one of the first domestic manufacturers to develop and produce a full series of WDM products, professional and reliable products and services for the 5G industry wholeheartedly help fuel!