Adiabatic processes in frequency conversion

Adiabatic evolution, an important dynamical process in a variety of classical and quantum systems providing a robust way of steering a system into a desired state, was introduced only recently to frequency conversion. Adiabatic frequency conversion allowed the achievement of efficient scalable broadband frequency conversion and was applied successfully to the conversion of ultrashort pulses, demonstrating near-100% efficiency for ultrabroadband spectrum. The underlying analogy between undepleted pump nonlinear processes and coherently excited quantum systems was extended in the past few years to multi-level quantum systems, demonstrating new concepts in frequency conversion, such as complete frequency conversion through an absorption band. Additionally, the undepleted pump restriction was removed, enabling the exploration of adiabatic processes in the fully nonlinear dynamics regime of nonlinear optics. In this article, the basic concept of adiabatic frequency conversion is introduced, and recent advances in ultrashort physics, multi-process systems, and the fully nonlinear dynamics regime are reviewed. Adiabatic frequency conversion allowed efficient scalable broadband frequency conversion and was applied successfully to the conversion of ultrashort pulses. The underlying analogy between undepleted pump nonlinear processes and coherently excited quantum systems was extended to multi-level quantum systems, demonstrating new concepts in frequency conversion. Additionally, the undepleted pump restriction was removed, enabling the exploration of adiabatic processes in the fully nonlinear dynamics regime of nonlinear optics. In this article, the concept of adiabatic frequency conversion is introduced, and recent advances in ultrashort physics, multiprocess systems, and the fully nonlinear dynamics regime are reviewed.