Quantum Electronics

Theoretical analysis of multiple quantum-well, slow-light devices under applied external fields using a fully analytical model in fractional dimension

Reza Kohandani, Hassan Kaatuzian

Published Jan 31, 2015• 7 citations

Abstract

We report a theoretical study of optical properties of AlGaAs/GaAs multiple quantum-well (MQW), slow-light devices based on excitonic population oscillations under applied external magnetic and electric fields using an analytical model for complex dielectric constant of Wannier excitons in fractional dimension. The results are shown for quantum wells (QWs) of different width. The significant characteristics of the exciton in QWs such as exciton energy and exciton oscillator strength (EOS) can be varied by application of external magnetic and electric fields. It is found that a higher bandwidth and an appropriate slow-down factor (SDF) can be achieved by changing the QW width during the fabrication process and by applying magnetic and electric fields during device functioning, respectively. It is shown that a SDF of is obtained at best.

DOI: 10.1070/qe2015v045n01abeh015596

Related papers

Analysis of the effects of applying external fields and device dimensions alterations on GaAs/AlGaAs multiple quantum well slow light devices based on excitonic population oscillation

Reza Kohandani, Ashkan Zandi, Hassan Kaatuzian

This paper demonstrates the effects of applying magnetic and electric fields and physical dimensions alterations on AlGaAs/GaAs multiple quantum well (QW) slow light devices. Physical parameters include quantum well sizes and number of quantum wells. To the best of our knowledge, this is the first analysis of the effects of both applying magnetic/electric fields and physical parameters alterations and the first suggestion for matching the prefabrication and post fabrication tuning of the slow light devices based on excitonic population oscillations. The aim of our theoretical analysis is controlling the optical properties such as central frequency, bandwidth, and slow down factor (SDF) in slow light devices based on excitonic population oscillation to achieve better tuning. To reach these purposes, first we investigate the quantum well size and number of quantum wells alteration effects. Next, we analyze the effects of applying magnetic and electric fields to the multiple quantum well structure, separately. Finally, physical parameters and applied external fields are changed for measuring frequency shift and SDF for coherent population oscillation slow light devices. The results show the available central frequency shifts in about 1.6 THz at best. Also the SDF value improvement is about one order of magnitude. These results will be applicable for optical nonlinearity enhancements, all-optical signal processing, optical communications, all-optical switches, optical modulators, and variable true delays.

Applied OpticsFeb 19, 20149 citations

Analysis and simulation of strained quantum wells slow light devices according to V-type EIT

Saeed Abdolhosseini, Hassan Kaatuzian, Bahram Choupanzadeh

This article investigates and improves optical properties of slow light devices. The device structure consists GaAs/AlGaAs [110] strained quantum wells (QWs) based on V-type electromagnetically induced transparency (EIT). In this paper, we use an analytical model in fractional dimension in order to simulate and analysis slow light device. Effects of well width variation have been investigated on exciton oscillator strength (EOS) and fractional dimension parameter. Influences of these parameters alterations have been illustrated in optical properties of slow light system such as slow down factor (SDF) and central energy of the device. Based on obtained results, we can adjust optical variables of slow light system with controlling the well thickness. Using proposed method, we have also estimated the maximum value of SDF about 9×103.

Iranian Conference on Electrical EngineeringMay 1, 20171 citation

Well width and alloy concentration dependence of optical properties of slow light devices

Hassan Kaatuzian, Reza Kohandani

This paper theoretically presents a technique for characteristics tuning of AlGaAs/GaAs multiple quantum well (MQW) slow light devices based on excitonic population oscillations. The multiple quantum well slow light device is analyzed and simulated using semiconductor Bloch equations. In addition the simulation results are shown for the quantum wells (QWs) of different width and barriers with different alloy concentration. The results demonstrate that the optical properties of the slow light device, such as central frequency and bandwidth, are dependent on quantum well width and aluminum percentage of the multiple quantum well structure. According to the best theoretical results, the central frequency of the device can be shifted in a range of 2THz.

Iranian Conference on Electrical EngineeringMay 1, 20153 citations

A theoretical study of the influence of barrier thickness variations on optical properties of a semiconductor multiple quantum well slow light device

Saeed Abdolhosseini, Hassan Kaatuzian, Reza Kohandani +1 more

The influence of barrier thickness variations on the operation of GaAs/AlGaAs multiple quantum well (MQW) slow light devices based on coherence population oscillations (CPOs) is explained. The variations are shown to affect the slow down factor (SDF) and bandwidth of these devices. Bloch equations and the analytical model in fractional dimension are used to analyse and simulate the slow light device. It is shown that other physical parameters of MQW structures (QW width and barrier alloy concentration) affect significantly the optical properties of the device. The presented approaches make it possible to achieve suitable values of SDF and focal energy by adjusting the barrier thickness, QW width and aluminium content. The maximum range of the centre frequency tuning is estimated to be about 1 THz in our calculations, while the slow down factor can reach a high value of 8.5 × 10 4 .

Quantum ElectronicsJan 29, 20181 citation

Electric field effects on multiple quantum wells slow light device

Hossein Shokri Kojori, Hassan Kaatuzian, Abodolbar Mallah

Summary from only given. This paper investigates the effect of applied electric field on frequency center, bandwidth and slow down factor of an slow light device. In this way, we consider the shift of exciton energy levels in quantum wells. Analysis and simulation of a basic GaAs/AlGaAs quantum wells optical slow light device shows that applied electric field can tune the frequency and time domain properties of an optical slow light device. Simulation shows that electric field could shift the limited gigahertz bandwidth of this device up to 1 THz. These achievements are useful in optical nonlinearity enhancement and all-optical signal processing applications.

Iranian Conference on Electrical EngineeringJan 1, 20110 citations

Analysis and investigation of temperature and hydrostatic pressure effects on optical characteristics of multiple quantum well slow light devices

Saeed Abdolhosseini, Reza Kohandani, Hassan Kaatuzian

This paper represents the influences of temperature and hydrostatic pressure variations on GaAs/AlGaAs multiple quantum well slow light systems based on coherence population oscillations. An analytical model in non-integer dimension space is used to study the considerable effects of these parameters on optical properties of the slow light apparatus. Exciton oscillator strength and fractional dimension constants have special roles on the analytical model in fractional dimension. Hence, the impacts of hydrostatic pressure and temperature on exciton oscillator strength and fractional dimension quantity are investigated theoretically in this paper. Based on the achieved results, temperature and hydrostatic pressure play key roles on optical parameters of the slow light systems, such as the slow down factor and central energy of the device. It is found that the slope and value of the refractive index real part change with alterations of temperature and hydrostatic pressure in the range of 5–40 deg of Kelvin and 1 bar to 2 kbar, respectively. Thus, the peak value of the slow down factor can be adjusted by altering these parameters. Moreover, the central energy of the device shifts when the hydrostatic pressure is applied to the slow light device or temperature is varied. In comparison with previous reported experimental results, our simulations follow them successfully. It is shown that the maximum value of the slow down factor is estimated close to 5.5×104 with a fine adjustment of temperature and hydrostatic pressure. Meanwhile, the central energy shift of the slow light device rises up to 27 meV, which provides an appropriate basis for different optical devices in which multiple quantum well slow light is one of their essential subsections. This multiple quantum well slow light device has potential applications for use as a tunable optical buffer and pressure/temperature sensors.

Applied OpticsSep 1, 20174 citations