Fiber Mode Scrambler, Knob Control, Graduated Scale

The FM-1 Fiber Mode Scrambler produces a stable mode distribution in a fiber and low insertion loss regardless of the light launch conditions. This condition is important when making accurate measurements of properties and losses due to fiber components. Its precision mechanism gently presses the fiber between specially designed corrugated surfaces to cause micro bending of the fiber. This dramatically increases mode coupling among guided modes (known as mode scrambling) and coupling of high-order guided modes to radiation modes (mode filtering). The distribution of power among the modes is then independent of the launch conditions of the light, simulating the distribution achieved after the light has traveled through several kilometers of fiber. The fiber is placed in an easily accessible slot. A knob controls the pressure applied to the fiber until the desired output distribution is achieved. Tests have shown that losses introduced are negligible regardless of launch condition. A graduated scale assures that the fiber may be removed and replaced and the pressure reset with high repeatability.