Discoveries and inventions periodically cause new technological developments within human societies. Key inventions and their accompanying economic and social changes can be seen as the main promoters of technological and structural progress. Many examples of change can be traced back to key inventions. At the end of the last century, one of the major lines of technological development was the implementation of electricity, the introduction of electric current. Inno vations were generated both by applying the "low quality" thermal and energy transmission properties, as well as by studying "high quality" characteristics like signal processing and electromagnetic wave propagation. In the field of signal processing, particular devices like the thermionic valve, the transistor and the (micro) chip deserve mention. Regarding energy generation, distribution and consumption, huge investments were made in coal and nuclear power plants, as well as in consumer and industrial electric appliances. Which innovations can be expected to improve or replace some of the applications (products, processes) of electricity? Thinking of an important technology invented about three decades ago - the laser - coherent light plays the key role in the process ("light amplification by stimulated emission of radiation"). Thus the new term technologies of light can be used for such innovations. Extending the definition, "technologies of light" or "photonics" can be defined as any methods, processes or products which make use of the spectrum of light, and any systems whose function is to study, measure, transform or transmit by means of light."