2024-03-06
Fiber optic patch cables are widely used in the fields of optical communication and optoelectronics, with insertion loss (IL) and return loss (RL) being key indicators. Insertion loss weakens the optical power in the light link, reducing receiver sensitivity; while return loss alters the spectral width of the light source's laser diode, introducing noise and potentially causing changes in the operating wavelength of the light source. The following will analyze the meaning and impact of insertion loss and return loss of fiber optic patch cables.
Insertion loss refers to the signal power loss caused by the insertion of a component into the transmission cable, typically manifested as attenuation. It is expressed in decibels as the ratio of output optical power to input optical power. Insertion loss is one of the key indicators for evaluating the quality of fiber optic patch cables, with lower values indicating better performance.
Return loss is caused by the discontinuity of the transmission link, resulting in power loss as some signals reflect back to the signal source during transmission. This discontinuity may be due to mismatched terminal loads or mismatched devices inserted in the line. Return loss is expressed in decibels as the ratio of reflected wave power at the transmission line port to the incident wave power, typically as a positive value.
Therefore, the higher the absolute value of return loss, the smaller the reflection, leading to greater signal power transmission. In other words, higher return loss values indicate better performance of fiber optic connectors. Factors affecting insertion loss and return loss of fiber optic patch cables mainly include the following:
The cleanliness and defects of fiber optic end faces have a significant impact on insertion loss and return loss. For example, scratches, pits, cracks, or particle contamination can all lead to higher losses.
The precision of end face alignment is also crucial. If the fiber cores are not accurately aligned, deviations during connector insertion will directly affect the level of loss.
Another key factor is the type of fiber optic end face. Physical Contact (PC), Ultra Physical Contact (UPC), and Angled Physical Contact (APC) are common types. UPC connectors have the lowest insertion loss due to minimal air gaps at the end face, while APC connectors achieve higher return loss using angled end faces.
In conclusion, understanding the insertion loss and return loss of fiber optic patch cables contributes to building higher-quality optical transmission networks. Therefore, when purchasing fiber optic patch cables, it is crucial to ensure that the measured insertion loss and return loss indicators meet the requirements to ensure the proper operation of the fiber optic system.
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