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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 14:57 |
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Conference: Bucharest University Faculty of Physics 2008 Meeting
Section: Solid State Physics and Materials Science
Title:
Characterization of Bragg structures and optical micro-cavities by Spectroscopic Ellipsometry
Authors:
Carmen S. Petrone*1, Marian Zamfirescu2, George Epurescu2, Aurelian C. Galca1, Ana Ioanid3, Maria Dinescu2
Affiliation:
1 National Institute of Materials Physics, Magurele, Romania
2 National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania
3 Faculty of Physics, University of Bucharest, Magurele, Romania
E-mail
petrone@infim.ro
Keywords:
microcavities, bragg reflectors, ellipsometry, polariton laser
Abstract:
In the last years, planar photonic structures such as semiconductor optical micro-cavities, attracted a lot of interest due to their capability to control both optical and electronic properties in the same device. When a micro-cavity structure is well designed and fabricated, the cavity mode can be coupled with the excitonic states of the semiconductor material embedded in the cavity, conducting to the polariton states of the cavity. Such boson type quasi-particle like the microcavity polariton, induces new and exciting effects such us stimulated polariton scattering, condensation, and even lasing. In order to obtain such polariton effects in a microcavity, the critical components which have to be attentively considered are the Bragg mirrors. Their reflectivity, transparency, absorption and homogeneity are decisive for the obtaining the desired effects.
In this work we designed, fabricated and characterized Bragg Mirrors and micro-cavities. Using the pulsed laser deposition technique (PLD) we obtained multilayer structures such us SiO2/TiO2 mirrors and ZnO based cavity with SiO2/TiO2 mirrors. The optical properties are measured by Spectroscopic Ellipsometry (SE) technique. The classical technique of angle resolved reflectometry gives us only few information about the amplitude of the reflected optical radiation. In contrast, SE provide us a wide range of information including the phase shift between the s- and p- polarizations of the reflected light. Acquiring such information allows to redesign and optimize the planar structures taking into account the distribution of the electromagnetic field inside the cavity. An improved cavity structure will assure a stronger photon-exciton coupling, and a more stable polariton states up to room temperature in a ZnO cavity.
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