Coupled InGaAs Quantum Dots for Electro-Optic Modulation

We investigated the growth of vertically coupled In0.75Ga0.25As quantum dots (QDs) by varying the GaAs spacer thickness (d). Vertically-aligned triple-layer QDs of uniform size and highest accumulated strain are formed with d = 5 nm. The electroluminescence (EL) characteristics for In0.75Ga0.25As QDs show an emission spectrum at optical wavelength (lambda) of 1100-1300 nm. The EL spectra exhibit the highest optical gain at lambda ~ 1200 nm, and the narrowest FWHM = 151 nm of the sample with d = 5 nm at injection current = 20 mA. Fabry-Perot measurements at lambda = 1515 nm of TE and TM polarizations were carried out to investigate the electro-optic modulation for a single-mode ridge waveguide consisting of vertically-coupled triple-layer In0.75Ga0.25As QDs (d = 5 nm). The linear (r) and quadratic (s) electro-optic coefficients are r = 2.99 x 10(-11) m/V and s = 4.10 x 10(-17) m(2)/V-2 for TE polarization, and r = 1.37 x 10(-11) m/V and s = 3.2 x 10(-17) m(2)/V-2 for TM polarization, respectively. The results highlight the potential of TE/TM lightwave modulation by InGaAs QDs at photon energy below energy band resonance.

Automated summary

The study investigated the growth of vertically coupled InGaAs quantum dots by varying the spacer thickness. It demonstrated the potential of InGaAs QDs for TE/TM lightwave modulation.