Frequency-temperature compensation in Ti3+ and Ti4+ doped sapphire whispering gallery mode resonators

J.G. Hartnett , M.E. Tobar , A.G. Mann , E.N. Ivanov , Jerzy Krupka


A new method of compensating the frequency-temperature dependence of high-Q monolithic sapphire dielectric resonators near liquid nitrogen temperature is presented. This is achieved by doping monocrystalline sapphire with Ti3+ ions. This technique offers significant advantages over other methods. A second sapphire resonator had the Ti 3+ ions converted to Ti4+ ions. The method left an unknown residual concentration of Ti3+ ions. We found that temperature compensation (turning) points existed for various modes in the Ti3+ doped sample from about 76 K (in H modes) down to 27 K (in E modes). Whereas the turning points for the Ti4+ doped sample were detected between 9 and 35 K. The mechanism of compensation in both cases was due to the paramagnetic susceptibility of Ti3+ ions. For the Ti3+ doped sample at 50 K the Q factor was highest in E modes at 4 million, whereas the H modes were about half a million or less. On cooling to 15 K the Q factor rapidly increased and at 4.2 K reached 1.7 billion in the E12,1, delta; mode. H modes increased also but to no more than 40 million. At 50 K in the Ti 4+ doped sample the highest Q factor was 16 million in the E 12,1, delta; mode, and reached 190 million at 5 K. The highest Q factors observed in H modes were about 5 million at 50 K rising to a little more than 50 million at 5 K
Author J.G. Hartnett
J.G. Hartnett,,
, M.E. Tobar
M.E. Tobar,,
, A.G. Mann
A.G. Mann,,
, E.N. Ivanov
E.N. Ivanov,,
, Jerzy Krupka IMiO
Jerzy Krupka,,
- The Institute of Microelectronics and Optoelectronics
Book Frequency Control Symposium, 1998. Proceedings of the 1998 IEEE International, 1998
Keywords in English4.2 K, 50 K, 5 K, 76 to 27 K, 9 to 35 K, Al2O3:Ti, compensation, cooling, copper, Couplings, Detectors, dielectric resonators, Doping, E modes, frequency, frequency stability, frequency-temperature dependence, high-Q monolithic sapphire dielectric resonators, H modes, liquid nitrogen temperature, low-temperature techniques, Q factor, residual concentration, Resonance, sapphire, sapphire whispering gallery mode resonators, Temperature, temperature compensation, Ti3+ doped sapphire, Ti4+ doped sapphire, Titanium, turning, voltage control, whispering gallery modes
Score (nominal)1
Citation count*43 (2015-08-04)
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