The development of laser diode-pumped solid state lasers (LDPSSL) and laser diode technology has accelerated in the last 20 years and revolutionized solid state laser technology. The advent of new diode laser arrays, bars, and stackable diodes, as well as developments in other material science and optics fields, enhanced the development of LDPSSLs. These developments have led to novel laser crystals and unique optical methods to couple the diode light into the crystal.
A solid state laser system is a combination of both the hosting crystal and the doped ion. In the case of rare-earth ions, the emission bandwidth is relatively narrow. The type of the doped ion determines the peak of the laser emission wavelength. Therefore, one can control the emission-wavelength peak by selecting the appropriate ion. Examples were discussed previously and include , , , , and for laser emission in the spectral range of 1â3 Î¼m. Also, a spectral shift of the emission peak of the same ion doped in various hosts is influenced to a small extent by the crystal field of the solid state host. The emission peak of is centered at 1060 nm, at 1064 nm, and Nd:YLF at 1047 or 1057 nm, depending on the emission polarization.
The thermal and mechanical properties of the laser crystals are dominated by the nature of the host laser crystal through the mechanical-strength parameters, thermal coefficient, hardness, elastic properties, thermal expansion coefficient, and other properties. The subject was discussed in more detail in Secs. 4.1 and 5.1.
Diode pumping is applied mainly to solid state laser systems that emit laser radiation in the spectral range of 1â3 microns; these ions include the rare-earth ions listed above doped in hosts such as YAG, YLF, , SFAP , SVAP , and others. The main advantages of a LDPSSL, which make it technologically useful, are its efficiency, reliability, and compactness (see the appendix for more detail).
Efficient pumping depends on the pump power per unit area (pump density) of the pumping source.