Semiconductor lasers for medical applications

Abstract: The ‘laser’ properties of semiconductor lasers are usually not as good as in ‘classical’ gas or solid-state lasers. Disadvantages include: lower power output; spatial coherence and beam divergence unsatisfactory without optics; usually operate in multimode regime; wide spectral width. Advantages include: can be directly pumped by an electrical current; extremely high efficiency; very small and compact; easy to connect to optical fibres; mostly low cost; light can be generated in a wide spectral region; tunable; and huge laser arrays with optical power of hundreds of kW can be constructed. Thus they are widely used in many applications, including medicine. In this chapter the physical principles, materials and methods of preparation, and electrical and optical properties of semiconductor lasers and diode lasers are described, focusing on medical applications.