Electric-field-induced refractive index changes in InGaAs-InAlAs asymmetric coupled quantum wells

Two kinds of InGaAs-InAlAs asymmetric coupled quantum wells (QW's) were numerically analyzed in an effort to enhance change in the refractive index (/spl Delta/n) at longer wavelengths where absorption coefficient is small. The analysis reveals the operating voltage, /spl Delta/n, chirp parameter, /spl Delta/n//spl Delta/k, (/spl Delta/k: change in the extinction coefficient) and figure of merit, /spl Delta/n//spl alpha/, (/spl alpha/: absorption coefficient) can be improved by these two kinds of the QW's. This improvement is caused by an abrupt electric-field-induced increase or decrease in the oscillator strength for the lowest heavy hole exciton.>