We fabricated a one-dimensional nanoporous silicon photonic crystal on a silicon insulator substrate by a cost-effective electrochemical method as an optical biosensor for the detection of DNA hybridization. In the first step, a transfer matrix method was used to calculate the corresponding reflectivity spectrum for the design of nanoporous silicon photonic crystals. Then silicon-on-insulator-based photonic crystals were prepared by a novel simple electrochemical etching. Genes were hybridized inside the porous silicon (PS) pores by aminopropyltriethoxysilane and glutaraldehyde and detected through frequency resolved reflectance measurements. A detection sensitivity of 17.445 nm/μM is demonstrated with good specific detection. The linear response range covers a concentration range of antifreeze protein gene from 0.625 to 10.000 μM. This high responsivity indicates that the silicon-on-insulator-based PS photonic crystal has significant potential for application in biological micro-electro-mechanical-systems technologies.
We present a fast, novel method for building porous silicon-based silicon-on-insulator photonic crystals in which a periodic modulation of the refractive index is built by alternating different electrochemical etching currents. The morphology and reflectance spectra of the photonic crystals, prepared by the proposed method, are investigated. The scanning electron micrograph and atomic force microscopy images show a very uniform structure and the porous silicon demonstrates an 829 nm wide photonic band gap.
We report the measurements of the nonlinear refractive index of a metal/porous silicon composite system as measured by the reflection Z-scan technique. The composite system is formed by using magnetron sputtering to deposit thin metallic films onto porous silicon anodized on p-type silicon. The experiment results indicate an enhancement over the nonlinear refractive index of the composite system, which suggests an opportunity to form new-type nonlinear-optical media consisting of porous silicon for nonlinear optical applications such as power limiting or optical switching.
Third order nonlinear properties of new composite materials obtained by embedding A new type π-conjugated poly
[2,1,3-benzoselenadiazole-(2,5-didodecyloxy-1,4-phenylene)ethynylene](PPE)in porous silicon are measured in 532nm.
The picoseconds measurements show a significant increase of nonlinear refractive index not only with respect to the
standard optical materials. The reason can be explained as follows, the Π-electron conjugation bond would be expected
to have a significant effect on the ground and excited state dipole moments and electronic transition energies of the
molecule and, consequently, could affect the third-order nonlinear optical property of the molecule. The result shows that
it is a promising candidate for further material development and possible photonic device applications.
We have designed and characterized a novel fractal Cantor multilayer porous silicon photonic crystal with a defect
embedded in its middle as an optical sensor for sensing of various chemical and biological species. Compared with the
common periodic structure one (such as Bragg) and some aperiodic structure (such as Thue-morse), it is more sensitive
because of the lower number of interfaces. This research lays the foundation for design all-silicon sensor for biochemical
sensing and can also be good applied in excellent filter.
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