980nm Single Mode Fiber Reflector Mirror

An example of a fiber total reflector used in an erbium-doped fiber amplifier. In this example, a fiber retroreflector is placed at the end of an erbium-doped fiber to reflect light back into the fiber in the direction of the incident light. A circulator is used to directly guide the input light and the amplified output light into their appropriate optical paths, so that the signal light can pass through the gain fiber twice, and the gain of the amplifier is absorbed and utilized more effectively. Another practical application of retroreflectors is to build adjustable retroreflectors, as shown in Figure 2. The feedback signal from the downstream retroreflector can cause instability in some devices, such as laser diodes. By using an adjustable retroreflector, the sensitivity of the device to retroreflection can be determined. The adjustable attenuator allows the user to introduce standard reflections into the device. By analyzing the retroreflection effect, the user can calculate the device's noise level, bit error rate, distortion and other parameters.