Brief Introduction of Optical Fiber System Design

Optical fiber is the abbreviation for light-guide fiber. Optical fiber communication is a communication method that uses light waves as the carrier and optical fiber as the transmission medium.

Brief introduction to optical fiber system design:

Ⅰ. Design ideas of optical fiber system

The designer can choose the most effective and cost-effective way to transmit the optical signal. To do this, the designer must understand the requirements and losses of the various components in the system. 

In addition, the designer must also consider the following aspects:

1. Is the fiber optic system to transmit video, audio, data, or a combination of these signals?

2. Are these signals one-way or two-way?

3. How far is the signal transmission distance?

4. What is the optical loss budget of the fiber optic system?

5. What is the result of comparing the total optical loss in the system with the maximum optical attenuation allowed by the optical transceiver?

Ⅱ. Optical transmission loss of optical fiber system

The optical loss value or total attenuation value is the sum of the losses of the individual components between the receiver and transmitter. 

The main causes of optical loss are:

1. Optical fiber loss per kilometer;

2. Loss of fiber coupler;

3. Connector loss;

4. Interface loss.

When calculating these losses, it is impossible to be very accurate. The optical component manufacturers will give the standard range and formulate tolerances for the following content, such as the type of connector, the life and status of the light source emitter, and environmental factors including temperature changes. When estimating the optical power loss, you can refer to the above loss table to make a budget.

Ⅲ. Maximum attenuation value of fiber optic system

Generally, optical transceivers are marked with the maximum attenuation index (or transmit power and receiving sensitivity). The higher the number (expressed in dB), the longer the optical fiber system can work. It is the maximum optical signal attenuation value that the optical fiber system can tolerate and work normally. The loss of the entire line, that is, the link loss, can be determined as follows:

1. Use optical instruments (such as optical power meters) to measure loss;

2. The last one to actually estimate the loss of each system component should consider the following factors, each factor has its associated loss value: connector, connector type, fiber type, fiber jumper/distribution board, optical margin, etc.

With the continuous advancement of manufacturing technology and processes, this loss value is also decreasing. Therefore, when estimating the transmission distance, in addition to considering the above factors according to the loss table, it is necessary to refer to the actual parameters stated by the fiber optic system component manufacturer. Adding the optical loss caused by these factors, if the total is less than the maximum attenuation value marked by the optical transceiver, the normal operation of the optical fiber system can be guaranteed. And this can usually be used as a reference standard for the success or failure of the design of an optical fiber transmission system.