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Modulateurs de cohérence en optique intégrée sur semiconducteurs III.V : guide biréfringent et interféromètre de Mach-Zehnder

Abstract : This study deals with the design, fabrication and characterization of coherence modulators integrated on III-V compound semiconductor substrates. We first explain the principle of coherence modulation, a technique of optical coding applied to the transmission and multiplexing of signals, based on the introduction in a two-waves interferometer of an optical path delay larger than the coherence length of the optical source. We have fabricated a first coherence modulator, a polarisation interferometer based on a highly birefringent ridge optical waveguide. Since III-V compound semiconductors are not birefringent we have developped an original structure which guides the sole fundamental modes TE0 and TM0 with a high form birefringence resulting from the stacking of several thin AlGaAs layers. At the waveguide output the two modes present an optical path difference of 230 mm which can be modulated by electro-optic effect and is greater than the coherence length of a 1.3 mm superluminescent diode. Next we fabricated a second modulator in the form of a highly unbalanced Mach-Zehnder interferometer. This two-waves interferometer is completely integrated in AlGaAs/GaAs and introduces an optical path delay of 100 mm due to the length difference between its two arms. In order to minimize the losses in this complex structure we etched trenches located at the outside of the bend parts. This solution was chosen after simulation of the device by the beam propagation method (BPM). The performances of the device are comparable to those of the former one. We thus fabricated the first coherence modulators integrated in III-V compound semiconductors which open the way to new applications in wavelength filtering, polarization control... in optical telecommunications networks.
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Contributor : Emilie Marchand <>
Submitted on : Thursday, September 22, 2005 - 10:23:57 AM
Last modification on : Friday, January 10, 2020 - 9:08:09 PM
Long-term archiving on: : Tuesday, September 7, 2010 - 5:36:01 PM


  • HAL Id : tel-00010242, version 1


Sabry Khalfallah. Modulateurs de cohérence en optique intégrée sur semiconducteurs III.V : guide biréfringent et interféromètre de Mach-Zehnder. Micro et nanotechnologies/Microélectronique. Université Paul Sabatier - Toulouse III, 1997. Français. ⟨tel-00010242⟩



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