1310nm Single-Mode Fiber Reflector

Examples of fiber total reflection mirrors used in erbium-doped fiber amplifiers. In this application, a fiber-based back reflector is placed at the end of an erbium-doped fiber, reflecting light back into the fiber in the direction of the incident light. A circulator is used to direct both the input and amplified output signals along their respective optical paths. This setup allows the signal light to pass through the gain fiber twice, effectively enhancing the amplifier's gain absorption efficiency. Another practical application of back reflectors is the construction of tunable back reflectors, as shown in Figure 2. Feedback signals from a downstream back reflector can cause instability in certain devices, such as laser diodes. By incorporating a tunable back reflector, the sensitivity of a device to back reflection can be determined. A tunable attenuator enables users to introduce a controlled reflection into the system. By analyzing the effects of back reflection, users can calculate parameters such as noise level, bit error rate, and distortion.