WDM comparison, CWDM, DWDM, CCWDM What is the difference?

WDM comparison, CWDM, DWDM, CCWDM What is the difference?
Wavelength division multiplexing (WDM), including CWDM(coarse wavelength division multiplexing) and DWDM(dense wavelength division multiplexing). It refers to the simultaneous transmission of multiple signals of different wavelengths coupled to a single optical fiber. It has a multiplexer and a demultiplexer. The multiplexer (MUX) transmits multiple signal wavelengths in one fiber at the transmitting end. A demultiplexer (DEMUX) separates multiple wavelengths of signal transmitted in an optical fiber at the receiving end. The main purpose of WDM is to increase the available bandwidth of optical fibers, which can be expanded by WDM without the need to lay more optical fibers, so it is widely adopted by telecommunications companies.

What is the difference between CWDM and DWDM?
Different wavelength intervals CWDM: wavelength interval ≥20nm, usually used 1470~1610nm eight bands, interval 20nm, (easy to fly 1260nm~1620nm) DWDM: Wavelength interval < 10nm, usually 1550~1570nm band, wavelength interval is 200GHz (1.6nm), 100GHz(0.8nm) or 50GHz(0.4nm), (easy to fly 1525nm~1565nm) modulated laser is different under normal circumstances, CWDM modulated laser uses uncooled laser, while DWDM uses cooled laser. The cooled laser uses temperature tuning, and the uncooled laser uses electronic tuning.

What are the advantages of CWDM vs DWDM?
Compared with DWDM, the biggest advantage of CWDM system is the low cost, and the device cost is mainly reflected in the filter and laser. The wide wavelength interval of 20nm enables CWDM to lower the technical requirements of the laser, simplify the structure of the optical multiplexer/demultiplexer, improve the yield, and therefore reduce the cost.
DWDM can be applied to long-distance transmission, compared with CWDM, DWDM with a tighter wavelength interval, can carry 8 to 160 wavelengths on a fiber, more suitable for long-distance transmission. With the help of EDFA (Erbium-doped Fiber Amplifier), DWDM systems can operate over a range of thousands of kilometers.
What are the differences between CWDM and DWDM application scenarios?
Based on the above different features of CWDM and DWDM, their application scenarios are also different:
CWDM is used in: metro access layer, telecommunications, enterprise networks, campus networks, etc. DWDM is suitable for: long distance, large capacity long-distance trunk network, or large capacity metro core node compared CWDM, DWDM, let's understand a mini version of CWDM - CCWDM, it is different from CWDM?
What is CCWDM?
CCWDM is called compact coarse wavelength division multiplexer and is a mini version of CWDM. It is based on the wavelength division multiplexing technology of TFF(thin film filter) and works in the same way as CWDM, except that the adjacent channels of CCWDM are cascaded in free space using parallel beams instead of optical fibers. Without the fiber used in the cascade, the CCWDM box is up to 10 times smaller than the standard CWDM package.
What is the difference between CWDM and CCWDM?
The CWDM system uses a low-cost, refrigeration-free distributed feedback (DFB) laser, while the CCWDM system has a different cascade structure with its collimator and filter welded to a common substrate.
A three-port filter for a specific wavelength of CWDM whose wavelength channel consists of two lenses and a TFF matched to that specific wavelength. The reflection port of each filter is connected to the common port of the next filter, and the filters are connected through a fiber optic connector, that is, a CWDM multiplexer.

The principle of CCWDM is to use an input lens to set the wavelength on the input fiber to λ1, λ2... λn light signal is focused on the first filter; The optical signal with wavelength λ1 is separated from the optical signal with wavelength λ1 by coupling to the first output fiber through the first filter and the first output lens. The remaining optical signals are reflected from the first slide to the next slide for optical signal separation; And so on until all the signals have been isolated. The coupling between wavelength channels is realized in the form of a straight light that travels along the line of the word.

From a cost point of view, CCWDM is cheaper than CWDM and DWDM. The industrial CCWDM coarse wavelength division multiplexer integrates Yifeiyang's own Free Space Optical system (FSO) technology platform, which can significantly improve optical performance, reduce manufacturing costs, small package size, and high scalability (4/8/10 or more channels), suitable for low-cost uncooled laser technology data communication networks/telecommunications networks.
5G is a key milestone in the history of communications, with a huge market and many challenges, and WDM solutions can save a lot of fiber resources. The company's product line has automated auxiliary production lines and advanced equipment, passive wave division series products have been in Korea KT and other operators have been commercially available in large quantities.