Nanoptics, Inc.

Gradient index (GRIN) materials have many applications in optical fiber communication, imaging and optical instruments. Almost all GRIN optical fiber or lenses are made of glass, which has limitations due to poor flexibility, difficulty in processing and high price. Therefore, polymers are being investigated to produce a GRIN material that solves the problems of GRIN glass. In this study, the optical transmittance and refractive indices of three kinds of miscible copolymers of Methyl Methacrylate/Benzyl Methacrylate, Methyl Methacrylate/Trifluoro‐ethyl Methacrylate and Benzyl Methacrylate/Trifluoro‐ethyl Methacrylate were examined.

A method was developed for fabrication of cylindrical objects with radially varying properties for functionally gradient materials (FGMs) in powder metallurgy, ceramics, and graded-index plastic optical fibers (GI-POFs) for communications.The method is a coextrusion process in which two polymers (materials a and b) with different properties (e.g., refractive index in the case of GI-POF fabrication) are fed sep. to a die (which will be called a GI die block (GDB)) where they are mixed in a desired proportion and a continuous variation of a property (e.g., refractive index profile) is created.The design of the GI die block depends on the properties of the material to be processed and the operating conditions.For the present study, the GDB was designed for a poly(Me methacrylate) (PMMA) with an average mol. weight (M_w) of 2 × 10⁶ and for a total flow rate of 1 kg/h at 200°.For fabrication of GI-POF, a random copolymer of benzyl methacrylate (BMA) and Me methacrylate (MMA) with the BMA content of 65 mol% and refractive index of 1.538 was used.When the BMA content is 45 mol %, the refractive index of the BMA/MMA copolymer becomes 1.525.While this method is capable of producing GI-POFs, its applicability may not be limited to GI-POFs.