The question inquires about the potential use of the sol-gel technique for producing fiber preforms (rods) and whether its application is limited solely to volume optics. The sol-gel technique refers to a process that involves the synthesis of materials in a solution, followed by gelation and subsequent solidification. In the context of fiber optics, fiber preforms serve as the initial structures that are later drawn into optical fibers.

The question seeks to determine whether the sol-gel technique can be employed to create these fiber preforms or if its scope is restricted to applications solely related to volume optics, which typically involve the manipulation of light within bulk materials. By understanding the capabilities and limitations of the sol-gel technique in relation to fiber preform production, a comprehensive answer can be provided.