Photonics INDEX

As shown in Fig. 7, a large increase in optical absorption occurs at higher photon energies above the HOMO-LUMO gap where electric dipole transitions become allowed. Transmission spectra taken in this range (see Fig. 7) confirm the similarity of the optical spectra for solid Ceo and Ceo in solution (decalin) [78], as well as a similarity to electron energy loss spectra shown as the inset to this figure. The optical properties of solid Ceo and C70 have been studied over a wide frequency range [78, 79, 80] and yield the complex refractive index n(cj) = n(cj) + and the optical dielectric function... 

Figure 7-13. (a) Linear absorption of DOO-PPV, (b) imaginary part of ) (proportional to two-photon absorption), and (c) real part ol (proportional to the nonlinear index of refraction. .). 

Combining the effects of index of refraction and penetration depth of photons, the predicted CCD QE for a 15 m thick CCD with the Lesser backside passivation process and single layer Hf02 AR coating is presented in Fig.13. The sensitivity to thickness of AR coating and transparency of the CCD to longer wavelengths is very evident. 

For the application of QDs to three-dimensional biological imaging, a large two-photon absorption cross section is required to avoid cell damage by light irradiation. For application to optoelectronics, QDs should have a large nonlinear refractive index as well as fast response. Two-photon absorption and the optical Kerr effect of QDs are third-order nonlinear optical effects, which can be evaluated from the third-order nonlinear susceptibility, or the nonlinear refractive index, y, and the nonlinear absorption coefficient, p. Experimentally, third-order nonlinear optical parameters have been examined by four-wave mixing and Z-scan experiments. 

ULTRACOMPACT OPTICAL SENSORS BASED ON HIGH INDEX-CONTRAST PHOTONIC STRUCTURES... 

Recently Hopman and al.15 applied a quasi one-dimensional photonic crystal (length 76 pm) for optical sensing. They measured the transmission spectrum as a function of the cladding refractive index. The cladding was varied using a liquid flow, of which the index was slowly varied over a small range (Figure 9). 

Figure 9. Cross-section of a refractive index sensor based on a quasi one-dimensional photonic crystal with grating period A = 190 nm. The top cladding over the grating is formed by a fluid contained in a cuvette that is sealed to the sensor chip.

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