Optical Specifications of Splitters

According to the communication industry standard of the People's Republic of China "Technical Conditions for Optical Fiber Couplers" YD/T893-1997 stipulates the optical index of the splitter
Include the following
1. Additional loss
The additional loss is defined as the DB number of the sum of the optical power of all output ports relative to the input optical power loss. It is worth mentioning that for optical fiber couplers, the additional loss is an index reflecting the quality of the device manufacturing process, reflecting the inherent loss of the device manufacturing process. The insertion loss only represents the output power status of each output port, not only the inherent loss factor, but also the influence of the splitting ratio. Therefore, the difference in insertion loss between different fiber couplers cannot reflect the quality of the device.
2. Uniformity
Uniformity refers to the variation of the insertion loss at each output end of the splitter that splits the light evenly
3. Spectral ratio
The splitting ratio is defined as the ratio of the output power of each output port of the fiber splitter. In the system application, the splitting ratio is indeed based on the optical power required by the actual system optical node to determine the appropriate splitting ratio (except for the average distribution), The splitting ratio of the optical fiber splitter is related to the wavelength of the transmitted light. For example, when an optical splitter transmits light of 1.31 μm, the splitting ratio of the two output ends is 50:50; when transmitting light of 1.5 μm, it becomes 70: 30 (the reason for this is that the fiber splitter has a certain bandwidth, that is, the frequency bandwidth of the transmitted optical signal when the splitting ratio is basically unchanged). So be sure to indicate the wavelength when ordering the fiber splitter.
4. Insertion loss
The insertion loss of the fiber optic splitter refers to the dB number of each output relative to the input optical loss. Its mathematical expression is: Ai=-10lg Pouti/Pin, where Ai refers to the insertion loss of the i-th output port; Pouti is The optical power of the ith output port; Pin is the optical power value of the input port.
5. Isolation
Isolation refers to the isolation ability of a certain optical path of a fiber optic splitter to optical signals in other optical paths. Among the above indicators, the isolation degree is more significant for the fiber splitter. In practical system applications, devices with isolation degree above 40dB are often required, otherwise the performance of the entire system will be affected. In addition, the stability of the fiber optic splitter is also an important indicator. The so-called stability means that when the external temperature changes and the working state of other devices changes, the splitting ratio and other performance indicators of the fiber optic splitter should remain basically unchanged. In fact, the stability of the optical fiber splitter depends entirely on the technical level of the manufacturer, and the quality of the products of different manufacturers varies greatly. In practical applications, I have indeed encountered many low-quality optical fiber splitters, not only the performance indicators deteriorate rapidly, but also the damage rate is quite high. The price, the price of the optical branch with low technology level is definitely low.
6. Spectral ratio error
The error between the split ratio actually used by the splitter and the designed split ratio.
7. Return loss
Return loss, also called reflection loss
Transmission: The scattered light that is continuously transmitted to the input is called retroreflected light. dB relative to the ratio of input light
The larger the return loss, the better, to reduce the impact of reflected light on the light source and system.
8. Polarization loss
Polarization loss PDL is the maximum transmission difference of an optical device or system in all polarization states. it is where the light equipment is located
There are ratios of maximum transmission and minimum transmission in the polarization state. Or the amount of change in insertion loss IL during vibration
9. Temperature loss
Generally speaking, the temperature loss TDL is the amount of change in the insertion loss IL during the temperature change.

10. Directionality