© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

Philosophical Transactions of the Royal Society of London Series A Mathematical and Physical Sciences

Multiple quantum well optical nonlinearities: bistability from increasing absorption and the self electro-optic device

David A. B. Miller

Published Dec 18, 1984• 6 citations

Abstract

Abstract This paper briefly reviews the nonlinear optical and electro-optical properties and applications of GaAs—AlGaAs multiple quantum wells, all of which are compatible with laser diodes or semiconductor electronics or both. They show large nonlinear absorption and refraction (associated with their strong room-temperature exciton resonances) applicable to all-optical devices. They also show large electroabsorptive effects, some of which are unique to the quantum wells at any temperature, which are so strong that optical modulators can be made with micrometre dimensions. A new class of optical bistability (due to increasing absorption) is also reviewed; combination of this with the electroabsorptive effects enables a new mirrorless optical switch called a Self Electro-optic Effect Device (SEED), which sets a new standard for optical switching energies, with energy densities reduced by a factor of six by comparison to even the best resonant cavity devices.

DOI: 10.1098/rsta.1984.0101

Related papers

Modelling of devices for optoelectronic applications: The quantum confined Stark effect and self-electrooptic effect devices

Eckehard Schöll

Electro-optical effects, such as the Franz-Keldysh effect in bulk materials or the quantum confined Stark effect in quantum well structures, lead to strong optoelectronic nonlinearities which form the basis for optical modulators and optically bistable devices. They result from a modification of the optical absorption properties by an applied electric field and are particularly pronounced in the case of low dimensional semiconductors. We review theoretical modelling and computer simulations of such optoelectronic devices in particular for ZnSe based quantum well structures, where excitonic features dominate even at room temperature. The field dependent absorption spectra are calculated by a many-body theory including the full electron-electron interaction. The transition from the quantum confined Stark effect, which is found for well widths smaller than the exciton Bohr diameter, to the Franz-Keldysh effect, which corresponds to the limit of wide wells, is studied. Optical bistability and switching is found in R-SEED and D-SEED configurations, and the optimization of the device performance is discussed.

TURKISH JOURNAL OF PHYSICS•Dec 3, 1999•3 citations

Optical nonlinearity, bistability, and signal processing in semiconductors

Nasser N. Peyghambarian, H. M. Gibbs

Semiconductors exhibit large optical nonlinearities near the band edge because of resonance enhancement. Optical bistability occurs when the optical nonlinearities are coupled with feedback. In bulk GaAs and GaAs–AlGaAs multiple-quantum-well superlattices, the nonlinearity arising from the presence of the free-exciton resonance has produced room-temperature optical bistability with a few milliwatts of power. The formation of biexcitons in CuCl, the saturation of the bound exciton on CdS, and band-filling effects in InSb, InAs, and HgCdTe lead to observation of bistability in these materials. A bistable etalon can be operated in an optical-gate mode to generate optical analogs of electronic gates such as and, or, and nor. It has been demonstrated that a GaAs optical NOR gate responds in ∼1 psec, using only ≲3 pJ of energy. However, because of the carrier lifetime of a few nanoseconds, the repetition rate of the NOR gate is now limited to a few hundred megahertz.

Journal of the Optical Society of America B•Jul 1, 1985•69 citations

A simplified analysis of the optical bistability of multiple quantum well etalons

H. Yokoyama

An analysis of static room-temperature-operation characteristics of a reflection-mode semiconductor multiple-quantum well etalon by a simplified two-level system formula of optical nonlinear properties and a computer simulation is presented. In the calculation for a GaAs/AlGaAs multiple-quantum-well etalon using the parameters reported in experimental measurement, it is shown that the very large excitonic optical nonlinearity is not effectively utilized for the optical bistable operation. This occurs because the effective positive-feedback mechanism which increases the etalon internal light intensity is suppressed when a hardly saturable background interband absorption tail is larger than a few thousand cm/sup -1/ at a wavelength where the large excitonic dispersive nonlinearity is observed.>

IEEE Journal of Quantum Electronics•Jun 1, 1989•13 citations

Thermally Induced Optical Bistability at Room Temperature in GaAs/AlGaAs Multiple Quantum Wells

Alan Miller, G. Steward, Peter Blood +1 more

Results on both dispersive optical bistability and bistability by increasing absorption are presented for multiple quantum wells consisting of 120 wells of 63 + thickness GaAs separated by 218 + thick barriers of Al0·4 Ga0·6As. Optical bistability is observed in the wavelength range 845–870nm for incident powers below 10mW. A second absorptive switching feature unique to quantum wells is observed at the n=2 transition. Wavelength bistability is also reported for the first time.

Optica Acta International Journal of Optics•Apr 1, 1986•8 citations

Contributions to optical absorption in GaAs/AlGaAs multiple quantum wells

Alan R. Kost, M. Kawase, E. Garmire

An examination of the contribution of excitons, compared to the continuum states, to the optical properties of GaAs/AlGaAs multiple quantum wells illuminates the mechanisms underlying nonlinear absorption and nonlinear refraction and yields information which is useful for optimizing devices which incorporate these materials. We have measured the absorption as a function of intensity at three different wavelengths—above the band edge, on the excitonic resonance, and far below the band edge—to separate the effects. We find that different well thicknesses have different saturation intensities both for excitonic and continuum absorption.

Annual Meeting Optical Society of America•Jan 1, 1987•1 citation

The Geometrical Dependence of Transient Optical Nonlinearities in Multiple Quantum Well Structures

R. J. Manning, D. W. Crust, Alan Miller +1 more

Semiconductor multiple quantum well structures exhibit very large, room temperature, nonlinear refractive effects associated with resolvable excitonic features [1]. These nonlinearities may find use in all-optical devices if sufficient refractive index change can be achieved before the exciton completely saturates [2]. A unique aspect of band gap resonant optical, nonlinearities in quantum wells is the spatial confinement of the generated carriers within the layers. We have exploited the excitonic refractive nonlinearity in GaAs/AlGaAs multiple quantum wells in two separate degenerate four wave mixing configurations. These compare the intra-well and cross-well contributions to highly anisotropic carrier diffusion and also allow measurement of carrier relaxation rates and the saturation of the excitonic nonlinear refraction with increasing intensity.

Topical Meeting on Optical Bistability (OB)•Jan 1, 1988•0 citations

Abstract This paper briefly reviews the nonlinear optical and electro-optical properties and applications of GaAs—AlGaAs multiple quantum wells, all of which are compatible with laser diodes or semiconductor electronics or both. They show large nonlinear absorption and refraction (associated with their strong room-temperature exciton resonances) applicable to all-optical devices. They also show large electroabsorptive effects, some of which are unique to the quantum wells at any temperature, which are so strong that optical modulators can be made with micrometre dimensions. A new class of optical bistability (due to increasing absorption) is also reviewed; combination of this with the electroabsorptive effects enables a new mirrorless optical switch called a Self Electro-optic Effect Device (SEED), which sets a new standard for optical switching energies, with energy densities reduced by a factor of six by comparison to even the best resonant cavity devices.

Electro-optical effects, such as the Franz-Keldysh effect in bulk materials or the quantum confined Stark effect in quantum well structures, lead to strong optoelectronic nonlinearities which form the basis for optical modulators and optically bistable devices. They result from a modification of the optical absorption properties by an applied electric field and are particularly pronounced in the case of low dimensional semiconductors. We review theoretical modelling and computer simulations of such optoelectronic devices in particular for ZnSe based quantum well structures, where excitonic features dominate even at room temperature. The field dependent absorption spectra are calculated by a many-body theory including the full electron-electron interaction. The transition from the quantum confined Stark effect, which is found for well widths smaller than the exciton Bohr diameter, to the Franz-Keldysh effect, which corresponds to the limit of wide wells, is studied. Optical bistability and switching is found in R-SEED and D-SEED configurations, and the optimization of the device performance is discussed.

Semiconductors exhibit large optical nonlinearities near the band edge because of resonance enhancement. Optical bistability occurs when the optical nonlinearities are coupled with feedback. In bulk GaAs and GaAs–AlGaAs multiple-quantum-well superlattices, the nonlinearity arising from the presence of the free-exciton resonance has produced room-temperature optical bistability with a few milliwatts of power. The formation of biexcitons in CuCl, the saturation of the bound exciton on CdS, and band-filling effects in InSb, InAs, and HgCdTe lead to observation of bistability in these materials. A bistable etalon can be operated in an optical-gate mode to generate optical analogs of electronic gates such as and, or, and nor. It has been demonstrated that a GaAs optical NOR gate responds in ∼1 psec, using only ≲3 pJ of energy. However, because of the carrier lifetime of a few nanoseconds, the repetition rate of the NOR gate is now limited to a few hundred megahertz.

An analysis of static room-temperature-operation characteristics of a reflection-mode semiconductor multiple-quantum well etalon by a simplified two-level system formula of optical nonlinear properties and a computer simulation is presented. In the calculation for a GaAs/AlGaAs multiple-quantum-well etalon using the parameters reported in experimental measurement, it is shown that the very large excitonic optical nonlinearity is not effectively utilized for the optical bistable operation. This occurs because the effective positive-feedback mechanism which increases the etalon internal light intensity is suppressed when a hardly saturable background interband absorption tail is larger than a few thousand cm/sup -1/ at a wavelength where the large excitonic dispersive nonlinearity is observed.>

An examination of the contribution of excitons, compared to the continuum states, to the optical properties of GaAs/AlGaAs multiple quantum wells illuminates the mechanisms underlying nonlinear absorption and nonlinear refraction and yields information which is useful for optimizing devices which incorporate these materials. We have measured the absorption as a function of intensity at three different wavelengths—above the band edge, on the excitonic resonance, and far below the band edge—to separate the effects. We find that different well thicknesses have different saturation intensities both for excitonic and continuum absorption.

Semiconductor multiple quantum well structures exhibit very large, room temperature, nonlinear refractive effects associated with resolvable excitonic features [1]. These nonlinearities may find use in all-optical devices if sufficient refractive index change can be achieved before the exciton completely saturates [2]. A unique aspect of band gap resonant optical, nonlinearities in quantum wells is the spatial confinement of the generated carriers within the layers. We have exploited the excitonic refractive nonlinearity in GaAs/AlGaAs multiple quantum wells in two separate degenerate four wave mixing configurations. These compare the intra-well and cross-well contributions to highly anisotropic carrier diffusion and also allow measurement of carrier relaxation rates and the saturation of the excitonic nonlinear refraction with increasing intensity.