Adiabatic second-harmonic generation.

Adiabatic three-wave mixing processes enable broadband, efficient, and robust frequency conversion by slowly varying the phase mismatch between the interacting waves along the interaction region. Up until now, this method was mainly used in the case in which one of the waves was undepleted. Here we experimentally study fully nonlinear adiabatic processes by implementation in type I and type II second-harmonic generation processes, where the undepleted pump approximation does not hold.

Calcite microcrystals in the pineal gland of the human brain: first physical and chemical studies.

A new form of biomineralization has been studied in the pineal gland of the human brain. It consists of small crystals that are less than 20 microm in length and that are completely distinct from the often observed mulberry-type hydroxyapatite concretions. A special procedure was developed for isolation of the crystals from the organic matter in the pineal gland.