Page 72 - AWSAR 2.0

48 || AWSAR Awarded Popular Science Stories - 2019
switch would not only consume less power to run but also work at faster speeds since light can travel much faster than electrical current.
The reason why a light-based switch is expected to consume less power is that we Cartoon showing the ON and OFF states of the
can engineer special media through which light can travel with much lower loss of power compared with electrical current. In a light- based transistor, one light beam called the control light controls the state
of another light beam called the signal light. For example, if the control light is off, the signal light would travel in a certain direction and reach the detector. We would call it the ON state. When the control light is on, the signal light would deviate from its path and not reach the detector. We would call this an OFF state.
Therefore, we wanted
to find a way to control the
direction of one beam of light
using another beam of light. To do this, we needed to pass light through a material or a medium other than air. Light interacts with such a medium in an unusual manner and changes its properties. This change in the medium’s property can then be used to direct the second beam of light. This together constitutes the equivalent of a transistor based
on light or an optical transistor. Currently, very few such media are known, which can be used for making an optical transistor, and most of these need a control light beam to be of very high power.
When we thought about tackling this problem, we initially decided to look for materials that may interact strongly with the light of very low power. Our system of choice was a special type of medium that consisted of extremely small particles called quantum dots. Quantum dots are made up of hundreds to thousands of atoms. Due to their unique sizes, they behave very differently from both the atoms, which are their basic building blocks and large objects (which we commonly refer to as bulk materials). Our research group had previously demonstrated the ability of quantum dots to strongly interact with light by devising ultra-low-power lasers based on quantum dots.
Thus, the problem that we defined for our research was: “How can we control a light beam by another low-power light beam using quantum dots as media?” During our journey through several experiments in the laboratory, we came up with a unique solution to this problem. To our surprise, the solution was not based on the basic electronic properties of quantum dots, which made them very interesting for many other applications, but rather
on their ability to strongly absorb light and convert this light energy into heat energy.
We found that a part of the light energy absorbed by quantum dots could heat up the solvents surrounding them and vaporize them. Thesolventvaporsformedasmallbubblewith a typical diameter of several micrometers to millimeters. Interestingly, this bubble acted
bubble-based switch.
All of us use mobile phones and computers. They make our life easy and happy. Calculations that would take hours to do on a paper can be done in fractions of a second on a computer. They also open up a world of information, knowledge and opportunities for each one of us.