Study of Fe3 -sapphire maser above 4K

Abstract

The Whispering Gallery Mode Maser Oscillator (WHIGMO) uses paramagnetic Fe3+ ions in HEMEX sapphire at low temperature, and has been described in many previous publications [1-7]. The fractional frequency instability has been demonstrated to be as low as σy(1s< τ100s) 10-14. This instability is normally measured at the frequency-temperature turnover point of the sapphire where the effects of temperature fluctuations on frequency are nullified to first order [8-9]. Usually the temperature is determined by the relative concentrations of several paramagnetic ions such as Cr3+, Mo3+, and Ti3+. In this paper, we show that Fe3+ ions have a strong effect on the turnover point. We compare the behavi..