Polymer optical fibers PMMA

FIGURE 5.29 Standard PMMA step-index polymer optical fiber, (a) Structure of cable, (b) Refractive index (n) profile. (After Knisley, J. 2002. Fiber optic lighting dries out, ecmweb.com/mag/electric fiber optic lighting.)... 

Transparent amorphous polymers such as poly(methyl methacrylate) (PMMA) have been found to be useful materials for polymer optical fibers (POFs) (1,2), waveguides (3), lenses (4), optical disks (5), and other optical components because of their excellent mechanical properties and easy processing. Many recently developed optical applications utilizing polarization techniques need optical polymers for maintaining more accurate polarization. However, applications of optical polymers are limited by birefringence which occurs in the process of device fabrication. 

The opacity of plastic foams, and polymers with scratched surfaces, is also governed by Fresnel s law. The n value of the gas which occupies the scratch indentation is much lower than that of the polymer. Light may be directed through rods of transparent polymers, such as PMMA. This effect may be enhanced when the rod or filament is coated with a polymer with a different refractive index, such as polytetrafluoroethylene (ptfe). Optical fibers utilize this principle. 

Recently, optical telecommunications tliat transmit large amounts of information via light signals have been rapidly replacing conventional electrical telecommunications. Optical polymers, such as poly(methylmethacrylate) (PMMA), polystyrene (PS), and polycarbonate (PC) are used for plastic optical fibers and waveguides. However, these polymers do not have enough Ihermal... 

From a material s point of view polymeric optical fibers are selected first of all on the basis of their optical characteristics. Table 4.4 summarizes the relationships between various physical parameters and fundamental optical properties. In recent years, Lorentz relationships between the refractive index and molecular parameters have been derived to guide experimentalists in selecting acceptable polymers. Representative optical characteristics of transparent polymers are reviewed in Table 4.5. The polymers CR-39, PMMA, and PC are... 

Frequency upconversion of 800 nm ultrashort 175 fs optical pulses by two-photon absorption in a stilbenoid compound-doped polymer (PMMA) optical fiber was reported [28]. By the intensity-dependent transmission method, the two-photon absorption cross section was deduced. The combination of a well-designed organic chromophore incorporated into a fiber geometry is appealing for the development of an upconversion blue polymer laser. Upconversion fluorescence and optical power limiting effects based on the two- and three-photon absorption process of a frans-4,4 bis(pyrrolidinyl)stilbene were investigated [29]. The molecular TPA cross section three-photon absorption (3PA) cross section g3 at 720-1000 nm were measured. The 3PA-induced optical power-limiting properties were also illustrated at 980 nm. 

For optical fibers, polymethylmethacrylate (PMMA) is an excellent transparent polymer. PMMA-based plastic optical fibers (POFs) have been extensively used... 

It has been shown that by irradiation of a PMMA polymer substrate with ions waveguide structures can be produced. Detailed results of the ion-induced chemical changes that lead to increased index of refraction have been reported elsewhere [156, 158]. A possible solution of the problem of exact coupling between the optical fiber and the device has been suggested. 

---