Analysis of Insertion Loss and Return Loss of Optical Fiber Patch Cord

Optical fiber jumpers are widely used in the field of optical communication and optoelectronics. Insertion loss (insertion loss) and return loss (return loss) are two important indicators of optical fiber jumpers. Insertion loss will weaken the optical power in the optical link and reduce the receiving sensitivity; The return loss will change the spectral width of the laser diode of the light source, introduce noise into the system, and even change the working wavelength of the light source. Now we will analyze what is the insertion loss and return loss of optical fiber jumper.

Insertion loss refers to the loss of signal power caused by the insertion of a device somewhere in the transmission cable. It generally refers to attenuation. It is expressed as the ratio of output optical power to input optical power of the port, in decibels (dB). Insertion loss is one of the standards to measure the quality of optical fiber jumper. The lower the insertion loss value, the better the insertion loss performance.

Return loss is the power loss caused by some signals reflecting back to the signal source during transmission due to the discontinuity of the transmission link. This discontinuity may not match the terminal load or the equipment inserted in the line. It is expressed as the ratio of the reflected wave power and the incident wave power at the transmission line port. The unit is decibel, and the value is generally positive.

Therefore, the higher the absolute value of return loss, the smaller the reflection, and the greater the signal power transmission, that is, the higher the return loss, the better the performance of the optical fiber connector. The main factors that affect the insertion loss and return loss of optical fiber jumper are as follows:

First, the cleanliness and end face defects of the optical fiber end face, that is, scratches, pits, cracks, particle contamination and other conditions on the end face, will lead to high insertion loss and return loss.

Second, the degree of accurate butt joint between the two end faces, that is, when the fiber cores are not precisely aligned, the insertion loss and return loss will be greatly affected when the connector cores are connected and the alignment deviation occurs.

The third is the type of optical fiber end face. The types of optical fiber end face include physical contact (PC), ultra physical end face (UPC), and inclined plane physical contact (APC). The UPC connector has the lowest insertion loss due to the minimum end air gap, while the APC connector can achieve the highest return loss due to the use of inclined optical fiber end face.