A type of fiber optic cable that uses a hard plastic tube with an inside diameter several times larger than that of the fiber is called _____.

The correct answer is Loose Tube. Loose tube fiber optic cables are specifically designed with a hard plastic tube that has an inside diameter that is significantly larger than the fiber itself. This design allows the optical fibers to move freely within the tube, accommodating temperature fluctuations and mechanical stresses. The extra space prevents the fibers from becoming overly stressed, which can lead to performance issues or potential damage.

The loose tube design is particularly beneficial in outdoor environments where the cable may be exposed to various environmental factors. The protective tube not only provides mechanical protection but also allows the fibers to expand and contract with temperature changes without affecting overall cable performance.

In contrast, other cable types such as simplex cable typically consist of a single fiber with no ample plastic tube to allow for movement, and multimode cables refer more to the type of transmission mode rather than the physical cable structure. Rigid fiber cables, on the other hand, do not provide the same level of flexibility and protection as loose tube cables, making the loose tube design the optimal choice for many installation scenarios.