Wavelength division multiplexing (WDM), including CWDM (coarse wavelength division multiplexing) and DWDM (dense wavelength division multiplexing), etc. It refers to the coupling of multiple signals of different wavelengths on a single fiber for simultaneous transmission.

It has multiplexer and de-multiplexer. The multiplexer (MUX) combines multiple signal wavelengths in a single fiber for transmission at the transmitter side; the de-multiplexer (DEMUX) separates multiple wavelength signals transmitted in a single fiber at the receiver side. The main purpose of WDM is to increase the available bandwidth of the fiber, which can be expanded by WDM without the need to lay more fibers.

What is the difference between CWDM and DWDM?

- Different wavelength intervals

CWDM: wavelength interval ≥20nm, usually using eight bands of 1470~1610nm with 20nm interval, (HTF: 1270nm~1610nm)

DWDM: wavelength interval <10nm, usually using 1550~1570nm band with wavelength interval of 200GHz (1.6nm), 100GHz (0.8nm) or 50GHz (0.4nm), (HTF: 1528nm~1565nm)

- Modulated lasers are different

In general, CWDM modulated lasers use uncooled lasers, while DWDM uses cooled lasers. 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, the device cost is mainly in the filter and laser. 20nm wide wavelength interval makes CWDM low technical index requirements for laser, optical multiplexer/demultiplexer structure simplifies, the yield rate increases, so the cost decreases.

DWDM can be suitable for long-distance transmission. Compared with CWDM, DWDM with tighter wavelength spacing, which can carry 8~160 wavelengths on a single fiber, is more suitable for long-distance transmission. With the help of EDFA (Erbium Doped Fiber Amplifier), DWDM systems can operate over thousands of kilometers.

What is the difference between CWDM and DWDM application scenarios?

Combining the above different characteristics of CWDM and DWDM, their application scenarios are also different.

CWDM is applied to: metro network access layer, telecom, enterprise network, campus network, etc.

DWDM is suitable for: long distance, large capacity long distance trunk network, or large capacity metro network core node

What is CCWDM?

CCWDM is called Compact Coarse Wavelength Division Multiplexer, which is a mini version of CWDM. It is based on TFF (thin film filter) WDM technology and works in the same way as CWDM, with the difference that CCWDM‘s adjacent channels are cascaded in free space using parallel beams instead of optical fibers. Without the fiber used for cascading, the size of the CCWDM package box is fully 10 times smaller than the standard CWDM package.

What is the difference between CWDM and CCWDM?

CWDM systems use low-cost, cooling-free distributed feedback (DFB) lasers, while CCWDM has a different cascade structure with the collimator and filter welded on a common substrate.

A three-port filter for CWDM at a specific wavelength has a wavelength channel consisting 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 to each other via fiber optic connectors, i.e., a CWDM multiplexer.

The CCWDM principle is to use the input lens to focus the light signal of wavelength λ1, λ2...λn on the input fiber to the first filter; the light signal of wavelength λ1 passes through the first filter and is coupled to the first output fiber by the first output lens to separate the light signal of wavelength λ1; the rest of the light signal is reflected by the first slide to the next slide for The remaining optical signals are reflected by the first slide to the next slide for optical signal separation; and so on until all signals are separated. The coupling between the wavelength channels is achieved in the form of a straight line that follows a "zigzag" path.

From the cost point of view, CCWDM is cheaper than CWDM and DWDM. 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. HTF has the capability to design and manufacture WDM. Ask for your requirements and we will provide you with customized services.