Development of an 8-12 GHz variable frequency microwave resonant cavity for optically-detected magnetic resonance (ODMR) of GaAs-related semiconductors

In order to do spin echo measurements of the T2 spin coherence time in GaAs and related materials, one must have a resonant microwave cavity; the resonance serves mainly to increase the strength of the magnetic field at the sample. In order to probe materials with g-factors as low as $\vert $g$\vert $ = 0.1 (such as quantum-confined GaAs samples, and bulk/quantum-confined AlGaAs alloys) in moderate magnetic fields ($<$ 7 T), we have selected a resonant frequency of around 10 GHz for the resonator design. In order to fit a 10 GHz cavity into moderately-sized ($<$ 1 inch) magnet bore, however, a high dielectric material must be used, a so-called ``dielectric resonator''. We will present the design and testing of such a resonant cavity (resonant mode: TE011), that additionally allows for optical access of the sample, as well as a highly-variable resonant frequency.