Optical Dissipative Solitons May Help Search for Alien Planets

Normal waves widen as they travel and eventually disappear. Soliton water waves, in contrast, can travel for miles without any significant change in their shape or amplitude. Now, scientists have discovered that so-called optical dissipative solitons can exist in small millimeter-size optical resonators. This could have huge implications for future technology.

Solitons were first discovered over 150 years ago in water canals. They represent a surprising phenomenon of wave propagation and have been seen in natural phenomena that includes moving sand dunes and space plasmas. One particularly unique property of solitons is that they can retain their shape because of non-linear and dispersive effects that stabilize the wave. In fact, solitons can even occur as pulses of light that can propagate through a suitable transparent medium, such as an optical communication fiber.

In this case, the researchers created optical resonators, which are crystals shaped to form a resonator that can guide a soliton light pulse on an endless circular path. When a soliton light pulse circulates inside the resonator, a small fraction of it can be extracted every time the pulse completes one roundtrip.

The scientists analyzed the extracted light pulses from the resonator and found them to be surprisingly short in duration. In fact, they were much shorter than one millionth of one millionth of a second. Due to the small size of the optical resonator, the time between two extracted pulses was extremely short and the pulse rate was very high.

So what sort of applications do these findings have? In astronomy, the high rate of ultra-short light pulses can be used to search for Earth-like planets. In addition, chemists can use this to identify unknown substances and the capacity of today's telecommunication networks can be boosted by orders of magnitude. In addition, the solitons can be used for low-noise microwave generation or in future space-based optical clocks. This would significantly improve today's geo-navigation.

The findings are published in the journal Nature Photonics.