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Fabrication of gradient optical filter containing anisotropic Bragg nanostructure
Bomin Cho1, Sungyong Um, Hee-Gweon Woo
1Department of Chemisrty, Chosun University, 375 Seosuk-dong, Gwangju 501-759, Korea.
Journal of Nanoscience and Nanotechnology
|November 23, 2011
Summary
Researchers created novel gradient optical filters using asymmetric Bragg structure porous silicon (PSi). These filters exhibit tunable rainbow reflections, with pore size and reflection wavelength controlled by lateral distance.
Area of Science:
- Materials Science
- Optics
- Nanotechnology
Background:
- Distributed Bragg reflector (DBR) structures are essential for optical filtering applications.
- Porous silicon (PSi) offers tunable optical properties through controlled fabrication.
- Gradient optical filters require precise control over structural parameters.
Purpose of the Study:
- To develop new gradient optical filters with asymmetric Bragg structures.
- To investigate the fabrication of anisotropic DBR PSi and its composite films.
- To analyze the relationship between structural modifications and optical reflection properties.
Main Methods:
- Preparation of asymmetric Bragg structure DBR porous silicon (PSi) using anisotropic etching.
- Fabrication of flexible anisotropic DBR PSi composite films by polymer casting.
- Characterization of film morphology using cold field emission scanning electron microscopy (CFE-SEM).
Main Results:
- Anisotropic DBR PSi exhibiting rainbow-colored reflection was successfully generated.
- Composite films showed decreased average pore size and porous layer thickness with increasing lateral distance.
- Reflection resonance was observed to shift towards shorter wavelengths as lateral distance increased.
Conclusions:
- Asymmetric Bragg structure DBR PSi is a viable material for gradient optical filters.
- The anisotropic etching method allows for controlled tuning of optical properties.
- Flexible composite films offer potential for advanced optical device applications.
