Passive and Active Optical Devices

Optical filters with a well-defined transmission band can be manufactured by 

However optical applications of PS are not restricted to passive devices, ft has been shown that electroluminescent solid-state devices based on silicon are feasible. 

Bulk silicon constitutes an optical long-pass filter, as shown in Fig. 7.6. The same is true for micro- and mesoporous silicon, for which the effective medium approximation (EMA) is valid in the visible regime. The dimensions of macroporous silicon are in the visible regime and the EMA becomes invalid. 

To calculate the optical transmittance of a single macropore, it can be modeled by two opaque screens with an aperture of diameter d at a distance l, as shown in the inset of Fig. 10.13. For such an arrangement the ratio nt of transmitted power to incident power of a wavelength X can be approximated by 

The short-pass characteristic of Eq. (10.11) is evident. Measurements of the spectral transmittance of macropore arrays with the pore axis parallel to the inci- 

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