Nd : Glass

There are a number of characteristics that distinguish glass from other solid-state laser host materials. Its properties are isotropic. It can be doped at very high concentrations with excellent uniformity, and it can be made in large pieces of diffraction-limited optical quality. In addition, glass lasers have been made, in a variety of shapes and sizes, from fibers a few micrometers in diameter to rods 2m long and 7.5 cm in diameter and disks up to 90 cm in diameter and 5 cm thick. The most common commercial optical glasses are oxide glasses, principally silicates and phosphates, that is, SiO2 and P2O5 based. Table 1.1 summarizes some important physical and optical properties of commercially available silicate and phosphate glasses. The gain cross sections at 10⁵³ nm of available phosphates range from 3.0 × 10⁻²⁰ to 4.2 × 10⁻²⁰ cm² and are generally larger than the 10⁶⁴ nm cross sections of silicate glasses. Silicate and phosphate glasses have fluorescent decay times of around 300μs at doping levels of 2×10²⁰ Nd atoms/cm³.

TABLE 1.1. Physical and optical properties of Nd-doped glasses.