Laser diode pumped Nd:YAG lasers are promising sources for the application of new wavelength standards because of their inherently low-frequency noise, small size, and high power.
The Nd:YAG lasers are used to study the hyperfine spectrum of ¹²⁷I₂ for establishing a portable wavelength standard at 532nm and 1064nm. The Nd:YAG laser frequency is locked to observed Doppler-free absorption lines of ¹²⁷I₂.The root Allan variance of the beat frequency between two I₂ stabilized laser systems follows 2.410^-10/ dependence, and reaches its lowest value of 3.310^-12 | for =10000s. The lasers are extremely stable and can be operated continuously for over one month.

Picture: Florescence of iodine molecule pumped by a Nd: YAG laser at 532nm. The strong transition of iodine at 532nm (R(56)32-0) is an excellent reference of laser frequency stabilization.