A five-layer asymmetric coupled quantum well (FACQW) is a novel potential-tailored quantum well that is expected to exhibit giant electrorefractive (ER) index change in a transparency wavelength region. We studied the GaAs/AlGaAs and InGaAs/InAlAs FACQW theoretically and experimentally. A GaAs/AlGaAs FACQW was grown by molecular beam epitaxy (MBE). Giant ER sensitivity |dn/dF| as large as 1.7 × 10^-4 cm/kV was observed in the FACQW phase modulator. A Mach-Zehnder (MZ) FACQW modulator was fabricated and the operation voltage was successfully decreased. For 1.55 μm wavelength region, an InGaAs/InAlAs FACQWs was also proposed and studied. We found that the InGaAs/InAlAs FACQW is also expected to produce a giant ER sensitivity |dn/dF|. The InGaAs/InAlAs multiple FACQW was successfully grown by MBE and the results of its photoabsorption current measurements are consistent with the theory. We proposed an MZ modulator and a 2 × 2 switch with the multi-FACQWs in the core. Driving voltages of the FACQW modulator and the switch with 1mm-long phase shifters can be decreased as low as 0.1~0.2 V.

Date Published: 26 November 2007
PDF: 12 pages
Proc. SPIE 6782, Optoelectronic Materials and Devices II, 67820W (26 November 2007);

Published in SPIE Proceedings Vol. 6782:
Optoelectronic Materials and Devices II
Yoshiaki Nakano, Editor(s)