Moisture adsorption effects in biaxial and chiral optical thin film coatings

Hodgkinson, Ian J.; Wu, Qihong; McGrath, Kathryn M.

doi:10.1117/12.351251

Cited by 19 publications

(12 citation statements)

References 7 publications

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“…However, this index contrast for PTFs is only about 28% greater than that of the template films, thus suggesting that the index contrast alone cannot explain the entire effect. It has previously been noted that water ( ) can infiltrate porous films and condense within them [33], possibly leading to unwanted shifts in the optical characteristics of porous thin film media. The effect of water infiltration can be quite dramatic and has been exploited to produce GLAD-based capacitive humidity sensors [34], [35].…”

Section: Optical Rotation Measurementsmentioning

confidence: 99%

Fabrication and optical characterization of template-constructed thin films with chiral nanostructure

Harris

Sit

Brett

2002

IEEE Trans. Nanotechnology

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We report the fabrication of thin films perforated by high aspect ratio helical or chevron pores by an extension of the glancing angle deposition (GLAD) technique. The perforated films were created by transferring the nanostructure of a GLAD template film into target materials such as polymers and spin-onglasses and subsequently removing the template. The pore shapes are shown to be highly controllable and films designed to suit particular applications are discussed. By a double templating technique, we replicate the structure of the original film using alternate materials, which are typically less suited to the unmodified GLAD technique. Helical films of Cu and Ni were created by this method and the process should be transferable to additional electrodeposited materials. The optical rotatory power of perforated thin films formed on glass substrates was characterized and perforated films were shown to be effective in rotating the polarization plane of linearly polarized incident light by as much as 1.4 m.

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Section: Optical Rotation Measurementsmentioning

confidence: 99%

Fabrication and optical characterization of template-constructed thin films with chiral nanostructure

Harris

Sit

Brett

2002

IEEE Trans. Nanotechnology

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“…Adsorption of toluene on the anisotropic TiO 2 film causes the refractive index of the film to increase due to the void volume ( n ≈ 1) being displaced by toluene ( n 800nm = 1.49), while the anisotropy of the film decreases because the refractive index contrast between the columns ( n columns ) and the surroundings ( n surroundings ) is reduced . Both of these changes are directly observed through specific Mueller matrix elements.…”

mentioning

confidence: 99%

Hybrid Generalized Ellipsometry and Quartz Crystal Microbalance Nanogravimetry for the Determination of Adsorption Isotherms on Biaxial Metal Oxide Films

May¹,

Flaherty²,

Mullins³

et al. 2010

J. Phys. Chem. Lett.

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Generalized ellipsometry and quartz crystal nanogravimetry are combined to determine adsorption isotherms and changes in the optical properties of biaxial TiO 2 thin films by monitoring changes in the Mueller matrix. Individual Mueller matrix elements, corresponding to a variety of polarization states, exhibit dramatically different sensitivities to the adsorption of toluene. While some elements are sensitive to structural anisotropy and orientation, others report uniquely on the refractive index. The fast (n a ) optical axis reflects the greatest change in refractive index due to the adsorption, leading to a decrease from Δn 800nm =0.4 to 0.1. This change is discussed in terms of the Bragg-Pippard (B-P) effective medium approximation, which is shown to accurately describe changes in optical behavior in response to adsorption. The integration of generalized ellipsometry with quartz crystal nanogravimetry establishes a highly sensitive technique for acquiring adsorption isotherms and for chemical optical sensing of structurally anisotropic thin films. SECTION Nanoparticles and Nanostructures

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“…In particular, theoretical research has shown that the Bragg regime of a chiral STF must shift accordingly, thereby providing a measure of the fluid concentration [37]. Qualitative support for this finding is provided by experiments on wet and dry chiral STFs [39].…”

Section: Fluid Sensorsmentioning

confidence: 50%

Sculptured thin films: accomplishments and emerging uses

Lakhtakia

2002

Materials Science and Engineering: C

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Sculptured thin films (STFs) are nano-engineered materials whose columnar morphology is tailored to elicit desired optical responses upon excitation. Two canonical forms of STFs have been identified. Linear constitutive relations for general STFs as unidirectionally nonhomogeneous (continuously or piecewise uniformly) and locally bianisotropic continuums are presented, along with a 4×4 matrix ordinary differential equation for wave propagation therein. A nominal model for the macroscopic properties of linear STFs is devised from nanoscopic considerations. The accomplished implementation of STFs as circular polarization filters and spectral hole filters is discussed, as also are emerging applications such as bioluminescence sensors and optical interconnects.

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Moisture adsorption effects in biaxial and chiral optical thin film coatings

Cited by 19 publications

References 7 publications

Fabrication and optical characterization of template-constructed thin films with chiral nanostructure

Fabrication and optical characterization of template-constructed thin films with chiral nanostructure

Hybrid Generalized Ellipsometry and Quartz Crystal Microbalance Nanogravimetry for the Determination of Adsorption Isotherms on Biaxial Metal Oxide Films

Sculptured thin films: accomplishments and emerging uses

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