Spectral characterization of the linear and quadratic electro-optic effects in GaAs/AlGaAs multiple quantum well waveguides

The electro-optic effect in GaAs/AlGaAs multiple quantum well stripe waveguides has been studied extensively for both TE and TM polarization in a spectral range close to the excitonic band edge. The effect has been resolved into two components, a linear electro-optic (LEO) effect and a quadratic electro-optic (QEO) effect. The LEO coefficients r₆₃ and r₃₃ have been measured to be -1.75*10^-12 m V^-1 and zero respectively, similar to that of bulk GaAs, with no significant wavelength dependence. The quadratic effect, however, has been shown to be highly wavelength-dependent and enhanced compared with bulk GaAs. A QEO coefficient as large as 140*10^-20 m² V^-2 has been measured at photon energies 28 meV from the lowest energy exciton. The spectral dependence of the quadratic effect has been studied for both TE and TM polarization.