Researchers at Israel's Institute of Technology, the Technion, published in Nature Photonics a new method to analyze and reconstruct the evanescent wave by combining two separate light beams to make a new wave of a different color. An evanescent wave, as opposed to a traveling wave, is a wave with rapidly decaying amplitude and no power transport, according to RP Photonics.The scientists mixed a laser beam with the evanescent wave to create a new frequency that can be seen and studied.
Guided waves, as in optical fibers and photonic integrated circuits, all contain specific frequencies and energy that can travel extremely fast and don't radiate outside of their containers. However, they do leave a trace: an evanescent wave that decays and cannot be detected with a standard microscope.
"The interesting bit was the information we could extract,” explained research leader Prof. Guy Bartal.
“By changing the direction of the electric field of the high-intensity pulses, we could see different shapes," he said. "We then found out that we are not just measuring the evanescent waves, but we can choose what information to take out of them."
The ability to study these trace waves could allow scientists to better understand and decipher evanescent wave information from photonic circuits.
"Below some spatial limit, information remains bound to the surface and cannot be seen by any camera. Our technique “releases” this information into radiation that can be detected – even with a commercial camera!" Bartal exclaimed.
The scientists call their technique Nonlinear Near-field Optical Microscopy. It is unique in that it requires little equipment and is inexpensive.
“We haven't even begun to explore the limits of this scheme and its applications,” one of the researchers, Kobi Frischwasser said. “It may very well help us to develop better methods of verification for photonic circuitry. "We are very excited about the future, and hope that many groups around the world will join us on our quest."