A mechanism for low-power all-optical switching in multiple-quantum-well structures

Abstract

We demonstrate a novel type of optical switching mechanism in pin separate confinement multiple quantum well (SCMQW) structures. By introducing additional large barriers into conventional InGaAs(P)/InP SCMQW structures, the transport of photogenerated holes can be controlled in such a way that they accumulate in the intrinsic region. This positive space charge leads to a local screening of the internal field in the optical confinement layer and to an enhancement of the internal field in the MQW region. We characterize the optical nonlinearity, which is based on the quantum confined Stark effect (QCSE), experimentally and theoretically. As the nonlinearity is observed at input powers <1 W/cm2 in the basic nonoptimized structures presented here, we propose to use our structure especially for low-power optical switches.

Frequency Resolved Optical Gating Studies of Strained Saturable Bragg Reflector: Anomalous Dispersion near Resonance Absorption of the Exciton Resonance

“…In the past work, the SBR sample exhibits enhanced reflection at around 800 nm and enhanced absorption at around 770 nm. 7) The build up data show that the sample has a strong mode-locking force at around 800 nm. The experimental setup is shown in Fig.…”

“…The nonlinearity of multiple quantum wells (MQWs) has been proposed for optical switching from large optical nonlinearities. [7][8][9] The predicted and measured large optical nonlinearities of a strained MQW (SMQW) have also been reported by several groups. [10][11][12][13] Moreover, the exciton through quantum confined stark effect of SMQW has been proposed for screening piezoelectric field and increasing oscillator strength that produces very large optical nonlinearities.…”

All-optical switching due to state filling in quantum dots

“…All-optical switching has mainly been performed using active elements such as semiconductor optical amplifier gates 1,2 . Photonic switching in passive materials [3][4][5][6] suffer from small all-optical nonlinearities, requiring a too high switching energy. Semiconductor quantum dots (QDs) are expected to provide improved all-optical nonlinearities 7,8 due to their delta-function density of states.…”

Hole transport over heterobarriers in InP based multiple quantum well structures

“…The modulation voltage is varied until the EM spectrum equals the LM spectrum. 6,8 From the modulation voltage and the intrinsic thickness the internal field is determined. The LM measurements were performed at very low optical input power to avoid accumulation of holes to the left of the transport barrier.…”

“…6 The basic switching structure ͑Fig. 1͒ consists of a conventional separate confinement MQW structure, where one quaternary heterobarrier is replaced by a higher barrier.…”