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Proceedings Paper

Theory Of An Electro-Optic Modulator Based On Quantum Wells In A Semiconductor etalon
Author(s): D. R. P. Guy; N. Apsley; L. L. Taylor; S. J. Bass; P. C Klipstein
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Paper Abstract

We present the design of an electro-optic modulator which is based on the quantum-confined Stark effect (QCSE) in GaAs quantum wells contained within the central layer of a Fabry-Perot etalon. The etalon mirrors are quarter wave stacks of Ga0.7A10.3As and AlAs, eliminating the need for the application of anti-reflection coatings. p-i-n-doping is employed with the undoped Or stack sandwiched between doped mirrors, enabling electric fields of the order of 105Vcm-1 to be readily developed across the quantum wells. Placing a multiple quantum well structure within an etalon resonant cavity gives flexibility of design in terms of operating wavelength and mode: Light incident perpendicular to the QW stack is modulated through the operation of the QCSE on the QW excitons, either electro-refractively by a change in the real part of the QW refractive index producing a wavelength modulation of the narrow-band Fabry-Perot transmission resonance or in electro-absorptive mode. The semi-empirical theory uses conventional multilayer optical matrix methods together with a recent theory of the QCSE which has been tested against the results of electro-reflectance experiments. In electro-absorption mode we find a ratio of 19:1 on:off at 857.5nm for 8 quantum wells. In electro-refractive mode, using 32 wells, we predict modulation from 10% to 76% reflection at 883nm. These figures exclude substrate effects. Extension of the theory to other materials systems is readily accomplished. We present the reflectivity spectrum of a high quality etalon in In0.53Ga0.47As/InP and find good agreement with the predictions of the optical matrix model.

Paper Details

Date Published: 11 August 1987
PDF: 8 pages
Proc. SPIE 0792, Quantum Well and Superlattice Physics, (11 August 1987);
Show Author Affiliations
D. R. P. Guy, Royal Signals and Radar Establishment (UK)
N. Apsley, Royal Signals and Radar Establishment (UK)
L. L. Taylor, Royal Signals and Radar Establishment (UK)
S. J. Bass, Royal Signals and Radar Establishment (UK)
P. C Klipstein, Imperial College of Science and Technology (UK)

Published in SPIE Proceedings Vol. 0792:
Quantum Well and Superlattice Physics
Gottfried H. Doehler; Joel N. Schulman, Editor(s)

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