In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including 3He gas, wherein if 4He gas is also present in the buffer gas, the ratio of the concentration of the 3He gas to the 4He gas is greater than 1.37×10−6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including 3He gas, wherein if 4He gas is also present in the buffer gas, the ratio of the concentration of the 3He gas to the 4He gas is greater than 1.37×10−6. Other embodiments are also disclosed.