What is the purpose of an optical amplifier?

An optical amplifier serves a crucial role in enhancing the strength of an optical signal without converting it to an electrical form. This is essential in communication systems, as signals can weaken over long distances due to dispersion and attenuation. By utilizing substances such as erbium-doped fibers or semiconductor optical amplifiers, these devices amplify the incoming light signal directly, enabling it to travel further without degradation. This amplification is vital for maintaining signal integrity in fiber optic networks, particularly in long-haul and high-speed data transmission applications.

The other choices pertain to different optical devices or functionalities that do not align with the primary objective of an optical amplifier. Converting light to electrical signals is a function of photodetectors, filtering specific wavelengths is characteristic of optical filters, and encoding data onto light waves is related to modulation techniques. Each of these functions plays a significant role in optical communications, but they do not fulfill the specific purpose of boosting optical signal strength, which is the primary function of an optical amplifier.