Integrated Electro-Optic Modulators/Nanowire Lasers Demonstrated

In the Oct. 10 issue of Applied Physics Letters, scientists at Harvard University in Cambridge, Mass., report the integration of electro-optic modulators with lasers based on crystalline nanowires. The devices may have a role in the development of nanophotonic systems for multiplexed optical sensing and for optical information storage and processing.

Using metallorganic vapor phase epitaxy and pulsed laser deposition growth techniques, the investigators produced CdS and GaN nanowires. They added electrodes either above and below or alongside the structures to act as a parallel-plate or fringe-field electro-optic modulator, respectively.

To characterize the performance of the devices, they optically excited the nanowires with either 405-nm light from a Ti:sapphire laser or 266-nm radiation from an Nd:YVO₄, applied a time-varying voltage to the electrodes and monitored the effect on the emission intensity. Modulation versus voltage measurements demonstrated no shift in the peak emission wavelength of the nanowire lasers and indicated modulation as high as 40 percent in the CdS device. Experiments performed on devices operating at below the lasing threshold indicated that an electroabsorption mechanism is responsible for the effect.