Optical switching based on transparency in a semiconductor double-quantum well

陈渊 Chen Yuan, 邝耘丰 Kuang Yunfeng, 陈爱喜 Chen Aixi

Kumar Kumar

Hamid Reza Hamedi

The problem of pulse propagation is theoretically investigated through a coupled semiconductor-double-quantum-dot (SDQD) nanostructure. Solving the coupled Maxwell–Bloch equations for the SDQD and field simultaneously, the dynamic control of pulse propagation through the medium is numerically explored. It is found that when all the control fields are in exact resonance with their corresponding transitions, a weak Gaussian-shaped probe pulse is transmitted through the medium nearly without any significant absorption and losses so that it can preserve its shape for quite a long propagation distance. In contrast, when one of the control fields is not in resonance with its corresponding transition, the probe pulse will be absorbed by the QD medium after a short distance. Then we consider the probe pulses with higher intensities. It is realized that an intense probe pulse experiences remarkable absorption and broadening during propagation. Finally, we demonstrate that this SDQD system can be employed as an optically controllable switch for the wave propagation to transit from an absorbing phase to a perfect transparency for the probe field. The required time for such switch is also estimated through realistic values.

Forough Bozorgzadeh, Mostafa Sahrai

Abstract We analyze the electromagnetically induced grating in a four-level inverted-Y double quantum well system. Based on the electromagnetically induced transparency, the Fraunhofer diffraction of a weak probe laser field is theoretically investigated. It is shown that the diffraction patterns are sensitive to both the absorptive and dispersive properties of the system. The effect of coupling and pumping fields intensity, frequency detuning, the relative phase of fields and the sample interaction length on diffraction pattern is then discussed. Our scheme may find potential applications in designing the semiconductor quantum well-based photonic devices, such as all-optical switches at low light levels.

V.A. Sinyak

Jin‐Hui Wu, Jin-Yue Gao, Ji-Hua Xu +4 more

We study the temporal and spatial dynamics of two light pulses, a probe and a switch, propagating through an asymmetric double quantum well where tunneling-induced quantum interference may be observed. When such an interference takes place, in the absence of the switch, the quantum well is transparent to the probe which propagates over sufficiently long distances at very small group velocities. In the presence of a relatively strong switch, however, the probe pulse is absorbed due to the quenching of tunneling-induced quantum interference. The probe may be made to vanish even when switch and probe are somewhat delayed with respect to one another. Conversely, our asymmetric double quantum well may be rendered either opaque or transparent to the switch pulse. Such a probe-switch ``reciprocity'' can be used to devise a versatile all-optical quantum interference-based solid-state switch for optical communication devices.