Phase modulation in GaAs/AlGaAs double heterostructures. I. Theory

Faist, J.; Reinhart, F. K.

doi:10.1063/1.345045

Cited by 32 publications

(3 citation statements)

References 27 publications

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“…A eo summarizes all voltage independent factors. Isotropic changes of the refractive index, e.g., due to free carrier absorption, 16 do not contribute to the anisotropic TEOS signal.…”

Section: Blochmentioning

confidence: 99%

Midbandgap electro-optic detection of Bloch oscillations

et al. 2000

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Bloch oscillations excited in a biased GaAs/Al x Ga 1Ϫx As superlattice are investigated in a time-resolved two-color electro-optic detection scheme. The detection of resonantly excited Bloch oscillations is based on the Pockels effect probed at a wavelength in the center of the band gap. The observed birefringence is induced by the macroscopic polarization of the electronic wave packets relative to the localized holes. The off-resonant detection away from optical transitions directly monitors the spatial dynamics of the electrons in amplitude and phase. The dependence of the amplitudes of the Bloch oscillating electrons on the applied electric fields are in good agreement with the electron-hole dipole lengths calculated by a quantum-mechanical model. Bloch1 and Zener 2 have proposed in their theoretical studies on the dynamics of electronic wave packets in periodic potentials a temporal and spatial oscillation of the carriers in the presence of a static electric field. The frequency and the spatial amplitude L of these Bloch oscillations ͑BO's͒ are ϭeFd/h and Lϭ⌬/eF, ͑1͒respectively, where F is the applied electric field, d the potential period, h Planck's constant, and ⌬ the electronic bandwidth. As proposed by Esaki and Tsu, this intriguing phenomenon can be realized in a biased semiconductor superlattice ͑SL͒.3 Here, BO's are excited by the coherent superposition of several electronic Wannier-Stark ͑WS͒ states 4,5 with a common hole state by short laser pulses. The localization lengths of the electronic wave packets deviate from the semiclassical picture of BO's ͓Eq. ͑1͔͒ if a fully quantum-mechanical calculation of the wave functions in the artificial semiconductor structure is used.6 Additionally, the amplitude of optically excited BO's depends on the exciting laser pulse width and energy that determine the initial conditions of the wave packets. Pathbreaking investigations on BO's have been performed in four-wave-mixing, 8,9 THz emission, 10 and resonant transmittive electro-optic sampling ͑TEOS͒ experiments.11 In recent years, the experimental determination of the spatial amplitude of the oscillating electronic wave packets has become an objective of the studies. The amplitude determination of BO's in a SL has been reported in a THz emission experiment.12 The amplitudes were calculated from the detected THz radiation power by applying a superradiance theory. Subsequently, the BO amplitude has been carefully determined in spectrally and time-resolved four-wave mixing experiments.13 Using this technique, the dependence of the amplitudes on the spectral position of the exciting laser pulses was investigated.14 Resonant TEOS experiments performed with optical detection spectrally integrated over WS transitions can only provide a qualitative analysis of the electronic dynamics due to nonlinearities of the electro-optic effect at the interband resonances.In this paper, we present the off-resonant electro-optic detection of Bloch oscillations in a GaAs/Al x Ga 1Ϫx As SL. BO's are excited resonantly, but detecte...

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“…A eo summarizes all voltage independent factors. Isotropic changes of the refractive index, e.g., due to free carrier absorption, 16 do not contribute to the anisotropic TEOS signal.…”

Section: Blochmentioning

confidence: 99%

Midbandgap electro-optic detection of Bloch oscillations

et al. 2000

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“…Having calculated the number of carriers that are injected inside the ring core as a function of bias, our next task is to determine the RI change of the core due to these injected carriers [31]. The injected carriers alter the RI through three mechanisms such as (i) band gap shrinkage (BGS), (ii) band filling (BF), and (iii) free carrier absorption (FCA).…”

Section: Calculation Of Index Change For a Given Carrier Densitymentioning

confidence: 99%

GaAs based long-wavelength microring resonator optical switches utilising bias assisted carrier-injection induced refractive index change

Ravindran¹,

Datta²,

Alameh³

et al. 2012

Opt. Express

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“…The refractive index change arises from three effects: the plasma (PL), the band filling (BF), and the band-gap shrinkage (BS).The equations for these effects in InGaAsP have been obtained from experimental results, Schraud [ 5 ] , and based on a semi-empirical model reported, Faist [6], for GaAs . The results from these equations accord well for high carrier concentration with previous results, Bennet [7].…”

Section: I1 -Ingaasp -Refractive Index Alterationmentioning

confidence: 99%

MMIC Based InP/InGaAsP Intensity Optical Modulator

Silva

Herczfeld²

SBMO International Microwave Conference/Brazil,

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The research presented in this paper concerns the development of a MMIC InPhGaAsP intensity optical modulator, suitable for chip level integration of photonic devices and MMICs. In the proposed codigluration the microwave field induces EL periodic structure via doping and electro-optic effects. The: interaction of light with the induced grating yields a modulated optical signal. The paper discusses the structure design anti the expected device performance. I -INTRODUCTIONThe merging of photonic and microwave devices on a MMIC chip will bring benefits to many applications: phased-array radar, antenna remoting, optical processing of microwave signal, and CATV signal distributioin. MMIC based optical detectors, such as InP based pseudomorphic HEMTs with cutoff frequencies well in the GHz range, has been reported, Martin [ 11. Inl-xGaxAsyP1-y quaternary is a suitable material for optoelectronic devices since it can be lattice matched grown on InP. The lattice-matching relation between the compositions x and y can be expressed as:Conventional photonic modulators are based on the linear electro-optic effect which is a y small in semiconductors, thus, requiring devices with long interaction length or large voltage, or both. A significant change in the refractive index and absorption can be achieved via the Franz-Keldysh effect which leads to the electrorefraction or quadratic electro-optic effect and electroabsorption. For photon energies far from de material band-gap energy the electrorefraction and electroabsorptiiori are weak , however as the photon energy approaches the band-gap energy both effects increase significantly. Thus in relation to the operation wavelength the semiconductor band-gap wavelength can be tailored to maximize the effects. In addition, a significant change in the refractive index can be obtained by the use of doping. Three effects contribute to the alterauion of the refractive index: the plasma, the band filling, and the band-gap shrinkage. These effects may be exploited in the fabrication of phase and intensity type modulators.It has been shown that InP/InC;aAsP intensity modulator based on electroabsorption, Lin [2], and phase modulator based on doping effects, Vinchant 131, offer small size and potentially large bandwidth, but suffer of high insertion loss or high drive voltage, or both. Recently, it has been reported, Lee [4],, that GaAs/GaAlAs phase modulator based on doping and electro-optic effects presents excellent performance in relation to size, bandwidth, and insertion loss. These results show thilt the combination of doping and electro-optic effects is a key element in the design of modulators with superior performance.It is the objective of this paper to propose an intensity optical modulator based on doping and electro-optic effects to be integ,rated with InP based MMICs.. The device design and expected performance are also presented. I1 -InGaAsP -REFRACTIVE INDEX ALTERATIONThe refractive index is function of the carrier concentration which can be changed by doping or depletion of...

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Phase modulation in GaAs/AlGaAs double heterostructures. I. Theory

Cited by 32 publications

References 27 publications

Midbandgap electro-optic detection of Bloch oscillations

Midbandgap electro-optic detection of Bloch oscillations

GaAs based long-wavelength microring resonator optical switches utilising bias assisted carrier-injection induced refractive index change

MMIC Based InP/InGaAsP Intensity Optical Modulator

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