Thin, flexible fibers made of high-quality glass, used to transmit signals more efficiently than with metal wires. In-game, fiber optics are a key component to high-tier electronic weapon modifications and settlement devices, such as laser turrets. With the Contraptions Workshop add-on, they can be used to produce energy weapons on the energy weapon forge.
49 can be obtained in the Jamaica Plain Town Hall basement by disarming a large amount of laser tripwires. This can be done indefinitely thus providing infinite supply of fiber optics and crystals, to do this simply press button beside the door for re-enabling the lasers and disarm them again.