According to the geometry optical principles, a high intensity infrared radiation system for medical application is designed. In this system, the infrared optical fiber's output energy density can reach 17 kW/cm2 after being focused, and the diameter of
Localized fields in the defect mode of one-dimensional photonic crystals with active impurity are studied with the help of the theory of spontaneous emission from two-level atoms embedded in photonic crystals. Numerical simulations demonstrate that the en