Propagation of ultrashort pulses of intense, infrared light through transparent medium gives rise to a visually spectacular phenomenon known as supercontinuum (white light) generation wherein the spectrum of transmitted light is very considerably broader than that of the incident light. We have studied the propagation of ultrafast (<45 fs) pulses of intense infrared light through biological media (water, and water doped with salivary proteins) which reveal that white light generation is severely suppressed in the presence of a major salivary protein, &agr;-amylase.
We propose the use of square arrays of multiple atomic lenses, produced by interference of four nearly collinear optical beams in atom lithography using dipole force. Simulated lithographic patterns are reported for collimated as well as divergent rubidium atomic beam traveling in such square arrays of optical channels. The proposed configuration has the ability to write large numbers of periodic structures in square arrays in a single step.