Low-index material

Fig. 12.3 Refractive index (a) and TE polarized modal field profiles of a CBNL designed for m 7, Les 0.852 pm, with 5 internal and 10 external Bragg layers, (b) A nonperiodic distribution of high and low index material is required in an annular Bragg resonator...

It is clear that in order to achieve the largest index differential it is desirable that the less reactive component have an index as much below that of the polymer formed from the more reactive component as is possible. This is difficult in practice because low-index materials, perhaps with the exception of fluor-inated species, are too compatible with most polymers. 

However, photons are not actually reflected at the interface, but rather tunnel into the low-index material by optical tunneling. As a result, the reflected beam of fight is shifted along the interface by a small amount (Ax = 2Goos-Haenchen shift. This shift is ty pically small for fluid diagnostic applications (Ax < 1 pm) as compared to the field of view. A typical field of view for the magnification of microscope objectives is on the order of several hundred micrometers. 

Fig. 4 Amplitude of the evanescent field intensity at the interface in the low-index material 2 for both parallel and perpendicular polarization of the incident electromagnetic field...

Bange D.E., Erickson D.D., Wood T.E., Wood W.P. Sol-gel products news. 3M cubitron 321 abrasive grain. J. Sol-Gel Sci. Technol. 2000 18 288-289 Bazin N., Andrew J.E., Mcinnes H.A. Comparison of different high and low index materials in the manufacture of high laser damage threshold mirrors at the 351 nm wavelength. J. Sol-Gel Sci. Technol. 1998 13 757-761... 

Bazin N., Andrew J.E., Mcinnes H.A. Comparison of different high and low index materials in the manufacture of high laser damage threshold mirrors at the 351 nm wavelength. J. Sol-Gel Sci. 

The angle (pi is measured in material 1. For interference filters with a high index material as the A./2 layer in the center, this angle is substantially smaller than the external angle. Filters with a high index material in the center have a much smaller wavenumber shift with external incidence angle than filters with a low index material or a Fabry-Perot interferometer with air or vacuum in the gap. 

Most fiindamental surface science investigations employ single-crystal samples cut along a low-index plane. The single-crystal surface is prepared to be nearly atomically flat. The surface may also be modified in vacuum. For example, it may be exposed to a gas that adsorbs (sticks) to the surface, or a film can be grown onto a sample by evaporation of material. In addition to single-crystal surfaces, many researchers have investigated vicinal, i.e. stepped, surfaces as well as the surfaces of polycrystalline and disordered materials. 

Collection of the product fraction should begin after a few milliliters of an intermediate fraction has been collected at 155°/25 mm. This material has a low index of refraction. 

Xu, Q. Almeida, V. R. Panepucci, R. R. Lipson, M., Experimental demonstration of guiding and confining light in nanometer size low refractive index material, Opt. Lett. 2004, 29, 1626 1628... 

The Bragg confinement mechanism allows great flexibility in engineering the radial mode profile. For example, it is possible to design a resonator in which the light is confined within a defect composed of low refractive index material or even air. By contrast, this would be impossible in the case of conventional TIR-based resonators. Such configuration is useful for sensing applications as discussed later. 

One possibility to obtain a relatively small leakage into the substrate is to introduce a thin film of metal or absorbing layer such as a polymer or a dye with a complex dielectric function, or a thin layer of low refractive index material... 

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