Our experiment revealed that the cross-phase modulation (XPM) power efficiency was enhanced by decreasing the doping density in InGaAs/AlAsSb coupled double quantum well (CDQW) waveguides with an AlGaAs coupling barrier. To interpret this enhancement and systematically study the physics of XPM, we implemented the eight-band k·p calculation based on the interband dispersion model under intersubband excitation [proposed by our group in Phys. Rev. B 75, 075308 (2008) for XPM]. This calculation allows for an evaluation of the contributions to XPM, not only from the lowest interband transition (HH1-e1), but also from higher transitions (LH1-e1, HH2-e2). By considering all of these contributions, the calculated carrier density dependence of the index change well explains the enhancement in XPM efficiency, which mainly results from the redshift of the interband absorption edge when the doping density is decreased. To further enhance the XPM efficiency, we decreased the Al composition in the coupling barrier in order to lower the interband absorption edges for both HH1-e1 and LH1-e1. We predicted that the XPM efficiency would be tripled by decreasing the Al composition from 0.5 to zero for a carrier density of ~1×10¹⁸ cm^-3.
No takes yet. Share an insight, caveat, or question.
Cong et al. (2009) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: