Optical frequency comb by giant nonlinear capillary waves

摘要

Nonlinear optical processes are essential for modern photonics and they are possible mostly whenlight is produced by a high-power laser. However, nonlinear effects of non-optical origin, such as those observedin acoustical and mechanical systems, are many orders of magnitude stronger than optical nonlinearities, andtherefore they can be induced with energy that is much lower than that of a laser pulse. Here, we experimentallyconfirm our theoretical prediction of the possibility to convert giant acoustic and capillary wave nonlinearitiesinto optical signals, thereby effectively reproducing the result of a conventional nonlinear-optical interaction. Weexcite highly nonlinear capillary Faraday waves on the surface of a thin layer of ethanol and we reflect a beamof low-power, incoherent light from these waves to produce an optical frequency comb. Our results can be usedin many areas of photonics, including new classes of biomedical sensors that do not rely on high laser powers.