Bending a laser beam

Using just water and sugar in order to create a mixture with a gradient refraction index  a laser beam can bent  as shown in the video below.

Youtube video: Bending a laser beam

This is the principle explaining the mirages, gradient index lenses and fibres.  Amaze your friends by telling them that you put a black hole behind the recipient in order to create a huge gravitational field which bends light beams (General theory of relativity). A friend was convinced that we put a strong magnet below !!!

When properly poured, the sweet water will create a mixture with a gradual refraction index. The bottom will have a higher refraction index than the top. When a light beam travels inside, its direction will bend continuously (principle of Fermat)

In order to success the mixture:

  1. Saturate the water with sugar. You can go faster by heating the water
  2. Put FIRST the fresh water in the recipient and then the sweet water at room temperature. The saturated water will sink creating the gradient.
  3. Do NOT shake or mix the solution once you pour the sweet water

Creative Commons License
Bending a laser beam by CAOS group is licensed under a Creative Commons Attribution-Non-Commercial-No Derivative Works 3.0 Germany License.
Based on a work at



Filed under Laboratory

3 responses to “Bending a laser beam

  1. Anonymous

    hey, i actually thought lasers were powerful???

  2. Steve Taylor

    Beautiful demo. Thanks for sharing it.

  3. tell why the sugar would bend the laser

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