Low loss optical waveguides and polarization splitters with oxidized AlxGa1-xAs layers
Author(s)
Advisor
Aydınlı, AtillaDate
1998Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Low propagation loss waveguides, operating at 1.55 fim optical wavelength,
are fabricated utilizing oxidized AhGai_a;As layers. MBE grown multilayer
semiconductor heterostructures are characterized before and after oxidation by
ellipsometric techniques. In fabrication of optical waveguides, reactive ion etching
method is used extensively. Loss measurements are performed, involving a
fiber input-coupled laser source setup using Fabry-Perot resonance technique.
Propagation loss of an AlGaAs based multilayer rib waveguide with oxidized
AhG ai_3,As top layer is observed to reduce from 6 dB/cm to as low as 1 clB/cm
lor TM and from 3.7 dB/cm to as low as 0.6 dB/cm for TE polarizations in the
presence of metal electrodes on top of the rib. These results arc compared with
loss measurements on standard rib waveguides. Polarization splitters are also
fabricated with the same material. Effect of the oxide layer on the polarization
splitter’s coupling length for TE and TM polarizations are measured. Polarization
extinction ratios as high as 12.4 dB are obtained. Polarization extinction
ratios are also attempted to be controlled by the use of electro-optic effect in Al.x,.Gai_a;As system. Only AC fields are found to be effective.
Keywords
Optical losswaveguide
coupler
oxidation
reactive ion etching
ellipsometry
Fabry-Perot
polarization splitter