Researchers at Linköping University, together with colleagues in China, have developed a tiny unit that is both an optical transmitter and a receiver.
As a demonstration of what it can do, one of the researchers types in a sentence on a computer screen, and the same sentence immediately appears on the neighboring screen, optically transferred from one diode to another.
The diode is made from perovskite, one of a large family of materials defined by their special crystal structure. Perovskites consist of metal and halogen and have proved to be versatile semiconductors that are easy and cheap to manufacture. They also have the useful property of both detecting and emitting light.
The researchers have now used it to develop a diode that can be directed in two directions: it can receive optical signals and it can just as easily transmit them. This means that text and photographs can be wirelessly transmitted from one unit to the other and back again, using two identical units. And so rapidly that we experience it as happening in real time.
All optical communication requires rapid and reliable photodetectors. Current optical communication systems use photodetectors made from materials such as silicon and indium gallium arsenide. These are, however, expensive and they cannot be used in applications that require low weight, flexibility, or large surfaces.
In order to demonstrate the potential of the diode, the researchers have built a monolithic sensor that detects heart beats in real time combined with optical, bidirectional communication. This is an example of how the device provides the ability to simplify and shrink the functionality of current optical systems because it can be integrated with traditional electronic circuits.