Another Point of Thought about Fiber Optics Which Take WDM as an Example

We usually defined unfamiliar things as mystical, or difficult to understand but must be associated with the creation of that which is not familiar and already understood. In fact, I think that the familiar thing or regular thing you often do it. Maybe you do not really understand it completely. You just know what you need it to do. For example, when you go up early to work and ready to go to have a shower, Do you know all the things that had to happen for that hot water to come out of the shower? Possiblely not, you just know that once you turn on the switch, you will have a warm shower. Have a think of all the happened things in a normal day, you may not have second though because they are so familiar. Turn on the light, Watch TV, have a call, send an email and so on.

This always makes me think about that when a new technology is brought in the daily life, we always keep evasive attitude towards it, and the improvements of benefits and so many converiences it brings to our daily life. Well, I set the fiber optics product as an example. WDM, wavelength division. Related product: 8 channel cwdm multiplexer. See the figure. They have a similar feature is that people all used it but they are not aware that they are. Well, if you ask me about what the optical wavelength division multiplexing is, I will be glad to tell you the answer in a special way.


While in the copper cabling, if you want to get multiple signals on the same cable, it needs various of technical phenomena and acronyms which you may think it too boring. Such as ASK, CPFSK, DTMF, FSK, MFSK, OFDM and others. In fact, it just used in the old common telephone.

white light

While in the optical wavelength division multiplexing, it likes this. When go out and see the bright sunny day, the light from the Sun is basically white color. However, you take that light and shine it through a triangular glass prism and voila, you are presented with a rainbow of different colors! Well, those colors that are visible to us. We all know scientists divided it as Red, Orange, Yellow, Green, Violet, Indigo and Blue.  Like the figure. As you can see, visible light is actually just a sliver of the total light spectrum. In fiber optics, we use the light at the near infrared side starting at 850nm all the way out to the far infrared side around 1620nm. Each color is related to its particular wavelength. For example, the color green has a wavelength between 495nm – 570nm in the visible spectrum. So, in its simplest form of optical fiber, we take an electrical signal and convert it to a wavelength of light. Then we combine several different wavelengths (multiplexing), each carrying its own signal and transfer it over a glass fiber which so small as a human hair. After you form a habit that understands a technology from a familiar thing which you use it everyday, you will find many differences and more interests in your common life.