C⁴⁺:YAG has become the solid-state passive Q-switch material of choice for 1 micron laser systems, offering several significant advantages over active acousto-optic and electro-optic devices, including:
• Eliminates the need for a high voltage power supply
• Reduce packaging size and weight
• Improved reliability and a longer lifetime in 1064 nm Nd:YAG lasers.
• Readily fabricated into high optical quality OEM components.
A small fraction of the chromium ions in YAG can be induced to change valence from the normal Cr³⁺ to Cr⁴⁺ with the addition of charge compensating impurities such as Mg²⁺ or Ca²⁺. The best measure of the Cr⁴⁺ concentration is the low power absorption coefficient alpha at 1064 nm. The typical values of alpha vary from 1-7 cm-1 for passive Q-switch applications.