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Omnidirectional reflector using nanoporous SiO2 as a low-refractive-index material
J Q Xi1, Manas Ojha, Woojin Cho
1Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
Optics Letters
|July 13, 2005
Summary
Triple-layer omnidirectional reflectors (ODRs) achieve high reflectivity across all angles. Internal ODRs using nanoporous silicon dioxide show potential for low-loss waveguide structures.
Area of Science:
- Optics and Photonics
- Materials Science
Background:
- Omnidirectional reflectors (ODRs) are crucial optical components.
- Achieving high reflectivity across all angles of incidence is a key challenge.
Purpose of the Study:
- To demonstrate internal ODRs incorporating nanoporous silicon dioxide (SiO2).
- To evaluate the reflectivity performance of these novel ODR structures.
Main Methods:
- Fabrication of triple-layer ODRs using GaP (semiconductor), nanoporous/dense SiO2 (dielectric), and Ag (metal).
- Experimental measurement of reflectivity, including angular dependence.
- Theoretical calculation of angle-integrated Transverse Electric (TE) and Transverse Magnetic (TM) reflectivities.
Main Results:
- Internal ODRs with nanoporous SiO2 (refractive index n=1.23) and dense SiO2 (n=1.46) were successfully fabricated.
- Calculated angle-integrated reflectivities for ODRs with nanoporous SiO2 reached R(int)/TE = 99.9% and R(int)/TM = 98.9%.
- High reflectivity was observed for all angles of incidence.
Conclusions:
- Nanoporous SiO2 is a viable low-refractive-index material for internal ODRs.
- These ODRs exhibit excellent performance, indicating high potential for low-loss waveguide applications.