In which component of a fiber-optics communication system do changes to the intensity of the optical signal occur?

The optical transmitter is the component in a fiber-optics communication system responsible for converting electrical signals into optical signals. This process inherently involves modulating the intensity of the optical signal to carry the information being transmitted.

In an optical transmitter, changes to the intensity can be achieved through modulation techniques, which adjust the light output to represent the digital data being sent. The transmitter typically uses a light source, such as a laser or light-emitting diode (LED), to emit light. By turning the light source on and off, or varying its intensity, the transmitter encodes the information onto the optical signal. Therefore, the modulation of intensity at this point is crucial, as it directly influences the quality and integrity of the data being carried over the fiber.

While optical receivers, amplifiers, and switches play vital roles in the transmission of the optical signal, they do not primarily focus on modulating the intensity of the signal as it originates from the source. Receivers primarily convert the optical signal back to an electrical form, amplifiers boost signal strength, and switches direct the flow of light but do not change the intensity for the purpose of data encoding. Hence, the optical transmitter is the correct choice for where changes to the intensity of the optical signal occur.