Today, data transfer is based on light pulses that are sent through fiber optic cables. The faster the light intensity varies, the faster information can be transmitted. However, fundamental physical limits of the lasers that generate the modulated light prevent the process from becoming much faster than it currently is.
With the help of spin lasers, researchers at Ruhr-Universität Bochum now want to encode information in the polarization of the light instead of in the light intensity. They generate a special form of circularly polarized light whose polarization state varies extremely quickly. These polarization oscillations use a quantum mechanical property of electrons, the spin, and are therefore not subject to the same limitations as the change in light intensity.
The surface emitters used for this purpose (vertical-cavity surface-emitting lasers) are based on GaAs wafers for wavelengths between 650 nm and 1300 nm; for wavelengths between 1300 nm and 2000 nm (long-wavelength surface emitters), at least the active zone consists of InP or GaInAsN. The aim of the Bochum team is to realize components that are many times faster than conventional technologies and also significantly more energy-efficient than current standard lasers.
