For experiments requiring up to 850 MHz (Model 1611) and 1 GHz (Model 1601) bandwidths and 500 ps rise times we recommend these fiber-optic receivers with a well-balanced combination of gain, bandwidth, and very low noise. The fiber-optic input works equally well with FC/PC-connectorized single-mode or multimode fiber. They have been engineered to eliminate most common sources of noise and drift, and have enough gain to pick up even very weak signals making them ideal optical front ends for systems requiring a low-noise input.