1.55 µm Wavelength Strain-Compensated InxGa1-xAs/InyAl1-yAs Electroabsorption Modulators with High Extinction Ratio and Low Polarization-Dependent Loss

Abstract

Photocurrent (PC) measurements were carried out to investigate the excitonic transitions in InxGa1-xAs/InyAl1-yAs multiple quantum wells with and without an applied electric field. Transmission electron microscopy showed that high-quality 11-period strain-compensated In0.64Ga0.36As/In0.47Al0.53As electroabsorption modulator structures with high-quality heterointerfaces were grown by molecular beam epitaxy. The results for the PC data at 300 K for several applied electric fields showed that many excitonic transitions shifted to longer wavelengths as the applied electric field increased. The calculated value of the interband transitions from the first electronic state to the first heavy-hole state were in qualitative agreement with those obtained from the PC measurements. The maximum extinction ratio at a wanelength of 1.55 µm under an applied voltage of -1.5 V was 14.3 dB, the polarization-dependent loss at an extinction ratio of 14.3 dB was less than 0.5 dB, and the coupling losses were below 1.5 dB per facet at 1.55 µm. These results indicate that the electroabsorption modulators fabricated utilizing srain-compensated In0.64Ga0.36As/In0.47Al0.53As multiple quantum wells hold promise for high-efficiency devices in the 1.55-µm spectral range.