To reduce reflectance as well as loss, how is the end of a connector ferrule polished?

The end of a connector ferrule is polished to a PC (Physical Contact) finish to reduce reflectance and loss in fiber optic connections. This type of polish creates a smooth, flat surface that allows two fiber ends to come into direct contact with each other when connected. This contact minimizes the air gap that can lead to light loss due to reflection.

A PC finish results in better alignment of the optical fibers, improving the signal transfer between them. The physical contact in this polishing technique reduces back reflection and increases the efficiency of the transmission. In environments where minimizing signal loss is critical, this method is preferred.

Other polishing types, such as an angled finish, are used for specific applications like reducing back reflection further in certain connectors but do not serve the general purpose as effectively as a PC finish does for standard fiber optic connections. Similarly, a matte or rough finish would not provide the necessary precision and smoothness required for effective light transmission between fibers, leading to higher loss and potential performance issues.