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Doppler effect on nanopatterning with nonlinear laser lithography

Just five years after invention of the laser, laser induced periodic structures (LIPSS) had been reported [1]. However, the structure period is not very uniform in LIPSS. Recently, with nonlinear laser lithography (NLL), long range ordered periodic surface structures had been maintained by exploiting various feedback mechanisms and nonlinearities [2]. Albeit, fine tuning of structure period remains challenging. Here, we present an analogy between Doppler effect and structure period of the NLL which adds a capability of changing the structure period.