Which method allows for less optical loss within a given optical link?

Fusion splicing is the method that allows for less optical loss within a given optical link. This process involves actually joining two optical fibers together by melting their ends using an electric arc. This results in a seamless connection that minimizes the amount of light lost at the junction. The alignment of the fiber cores in fusion splicing is highly precise, which enhances the transmission efficiency and maintains the integrity of the light signal.

Optical losses during transmission can occur due to misalignment or poor joint quality, which fusion splicing effectively mitigates. This method is preferred in many telecommunications applications because it results in lower insertion loss and returns loss compared to other methods.

Other methods, such as score and cleave or using pigtails, typically introduce more loss due to the potential for imperfect fiber end geometry or misalignment. Mode coupling pertains more to the effects of light propagation within the fibers rather than the fidelity of the joint connection, thus not directly contributing to reducing optical loss in the context of connecting fibers.