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Laser Induced Periodic Surface Structure: An Experimental And Theoretical Review

We summarize the work conducted by our group over the past seven years on the development of coherent surface structures on solid surfaces during illumination by single, intense laser beams. We show how interference effects lead to the formation of structures on many different types of solids with a periodicity which is related to the wavelength of light and angle of incidence of the beam. The spatial spectrum of such structures and their detailed morphology, however, can depend on beam polarization and pulse width. The latter parameter, in particular, can grossly alter the nature of the feedback which allows these structures to develop and grow from a randomly rough surface. We demonstrate these differences with structures generated by nanosecond pulses and continuous beams on silicon and germanium. Most recently, a new class of periodic structure has been generated on silicon and germanium surfaces by picosecond laser pulses at repetition rates of 80 MHz. These structures have a periodicity nearly an order of magnitude smaller than the wave-length of light and are linked to the generation of surface acoustic waves by strongly absorbed light. In all cases we offer an overview of the key experimental observations and discuss the salient theoretical ideas without attempting to be detailed or rigorous.