Insertion loss (IL) refers to the reduction in signal strength when a device, such as a fiber optic connector, is inserted into a transmission line. Measured in decibels (dB), a lower IL value indicates less signal loss, which signifies better performance.

Return loss (RL) measures the loss of signal power due to reflections caused by mismatched or discontinuous connections in the transmission line. A higher RL value means less reflected signal, resulting in better transmission quality. In simpler terms, higher RL values reflect better connector performance and signal quality.

Several factors in fiber optic networks can lead to increased insertion and return loss:

• Misalignment of fiber ends: Improperly aligned fiber connectors cause partial signal loss.
• Fiber cable end-face quality: Irregularities or contamination on the fiber cable end-face can disrupt signal transmission and increase loss.
• Material mismatch: Differences in the optical properties of materials can lead to greater reflection and loss.
• These issues emphasize the importance of precision and cleanliness in fiber optic connections to maintain optimal transmission performance.