• Question: How do you make the tiny devices to turn lazer beams on and off

    Asked by anon-244170 to Pan-ngum, Natalia, Mick, Filipe, Bruce on 10 Mar 2020.
    • Photo: Michael Schubert

      Michael Schubert answered on 10 Mar 2020:

      I’m afraid the only lasers I have ever used just had ordinary switches! You would press a button to turn them on and off, just like a torch or lamp. In an electrical circuit, the wires and devices have to make a complete circle to turn on the light – and it’s the same for a laser. A switch or a button interrupts that circle and turns the light or laser on and off. I know that some lasers have switches that are controlled by a computer, but they work the same way: the computer interrupts the flow of electricity to the laser to turn it off, and lets it flow again to turn the laser back on.

    • Photo: Filipe Richheimer

      Filipe Richheimer answered on 10 Mar 2020:

      Yes, as Mick already said, you need electricity for a laser to work. If you turn off the electricity, the laser stops working. For safety reasons, sometimes you can place a shutter in front of the laser. The shutter then blocks the beam in emergency situations. That would be another way to “turn off a laser”, blocking the beam with an opaque surface.

    • Photo: Bruce Saleeb-Mousa

      Bruce Saleeb-Mousa answered on 11 Mar 2020:

      I make these devices as part of my research. The way we make them is we start off with a special material called a semiconductor. This allows electricity to pass through it in certain conditions but not in others. We make the devices by using specialised equipment to eat away the bits of material we don’t want which leaves behind the structure we need – a bit like making an ice sculpture starting with a block of ice. Once we have this structure we can then use it to switch laser beams on and off. If we shine the laser beam onto the device then it passes straight through it like a window. The clever part is when we connect the device to a battery and let electricity flow through it. This makes the laser beam bend inside the device and it no longer passes through – turning the laser beam off. This is better than just turning the laser itself off since when you turn a laser on it takes a while for it to stabilise and become useful enough to use in an experiment. Since laser beams are used in a lot of different physics experiments these devices could be very useful in improving their results.

Comments