We cannot imagine our life without light. From the first ray of Sun in the morning to the lamp in the night, light accompany us in all the activities. In modern life, three most important sources of light, which I think make major impact on life are the Sun, the light emitting diode (LED) and the laser. We always come across these sources in one way or the other.
The Sun is undoubtedly the most important one. It is a constant source of energy for us. It is the most important factor that influenced the way life evolved on Earth. From photosynthesis, which is responsible for making food in plants to the beautiful world we see and to meeting our energy requirements, the Sun is pivotal to our life. In recent years there has been tremendous advancement in the area of solar photovoltaic, a process which converts light into electrical energy through a variety of materials. Traditional bulky solar panels are soon going to be replaced by flexible thin film polymer solar cells. Now these cells can also be coated on your car and generate electricity while you drive in the Sun. You can simultaneously get electricity from the window pane of your room while you read a newspaper in sunlight. With petroleum energy sources getting exhausted rapidly, solar energy is the only clean energy option that can meet the energy requirements of our future generations.
Second important light source on my list is the LED. This tiny source of light is not only lighting up our world in a big way but also creating high resolution display screens for our smartphones, computers, and televisions. After the Sun sets down, LEDs are probably the most seen source of light around us, be it in indicators in electronic devices, in traffic signal lights, remote controls, toys, or decorative items. Advancements in organic LEDs have made it quite efficient and flexible too. White LED lamps are replacing fluorescent tube lights rapidly and white LEDs are creating high resolution display screens. No wonder the Nobel Prize in Physics 2014 went to the blue LED, which was crucial to create white light.
Third most important source of light that influenced our lives is laser. Soon after its invention in 1960, this highly coherent, directional and powerful source of light brought revolution and gave birth to several new branches of science and engineering. Advancements in nonlinear optics, holography, precision cutting, welding and drilling, laser-guided defense equipments, and most importantly optical telecommunication could be possible only because of the laser. Today, color of light when passing through a crystal can be changed from red to blue, a 3D image of an object can be created in space, data can be read from and written to a compact disc, missiles can be guided by laser beam, very fine tiny holes can be drilled in thick metal sheets, nuclei can be fused to generate nuclear power, pictures and video can be shared with our friends thousands of miles away, thanks to advancements in lasers. Lasers have made our world very small through optical telecommunication. Communication is our fourth most important basic need after food, shelter and clothing. Optical telecommunication has made the flow of information considerably fast. Voice, video and internet data ride on light from a laser diode and travel thousands of miles through hair-thin optical fiber at unprecedented rate to reach our colleague, friends and family. This blog is also reaching you through light. Indeed, life without light is unimaginable.
Vipul Rastogi is an Associate Professor in the Department of Physics at Indian Institute of Technology Roorkee, India. His current research interests are optical fiber designs for high power lasers and high data rate optical communication, optical fiber sensors, and optoelectronic devices. He has published over 130 research papers in refereed journals and conferences. He is a Senior Member of Optical Society of America, Life Member of Indian Laser Association and Fellow of Optical Society of India. IIT Roorkee honored him with an Outstanding Teacher Award in the year 2011.