Which device transmits pulses of light into the fiber and detects the amount of reflected light?

The optical time domain reflectometer (OTDR) is specifically designed for the purpose of transmitting pulses of light into a fiber optic cable and measuring the amount of reflected light. When light pulses are injected into the fiber, they travel through the cable and any imperfections or faults within the fiber cause some of the light to be reflected back to the OTDR. By analyzing these reflections, the OTDR can provide crucial information about the condition of the fiber, including the location and severity of any faults, splices, or connectors within the system.

This ability to detect and analyze reflected light makes OTDR a vital tool for maintaining and troubleshooting fiber optic networks. It plays a significant role in monitoring the integrity and performance of these systems, ensuring that they operate effectively.

Other devices listed have different functions. For instance, an optical fiber amplifier is used to boost the signal within a fiber optic path, an optical power meter measures the intensity of light in a fiber but does not analyze reflections, and an optical return loss test set measures the amount of reflected light but does so without the capability of pulsing light into the fiber for a time-domain analysis. This distinction highlights the unique capabilities of the OTDR in providing detailed assessments of fiber optic networks.