Microwave Solid-state Masers

Room-temperature solid-state maser

“…Why conventional solid-state masers 5,6 cannot be made to work at room temperature is understood 19 . The most serious problem is that the rate of spin-lattice relaxation, , thus the microwave power required to saturate the maser's pump transition and hence the required thermal cooling power of the maser's refrigerator, increases extremely rapidly with the absolute (lattice) temperature T of the maser crystal.…”

“…As LNAs, conventional solid-state masers 5 offer low residual noise temperatures 6 and, in contrast to micro-fabricated devices, are extremely rugged with respect to electromagnetic shock and overloading. Furthermore, they exhibit low intermodulation distortion 6 , so reducing interference from out-of-band signals, and low 1/f noise 7 .…”

Influence of the electron spin resonance saturation on the power sensitivity of cryogenic sapphire resonators

“…χ and χ represent respectively the phase shift and the power absorption induced by the Electron Spin Resonance (ESR) [12]. Let us assume that the sapphire crystal contains a density N of a paramagnetic ion presenting in its ground state two energy levels |m and |n separated by the ion ESR frequency ν mn .…”

A 32-GHz reflected-wave maser amplifier with wide instantaneous bandwidth

“…In a maser with a uniform magnetic field and 30 dB of electronic gain, the 3-dB bandwidth is 20 MHz, about one-third of the linewidth. Therefore, to achieve masers with wider instantaneous bandwidths, it is common practice to inhomogeneously broaden the line shape by placing different parts of the ruby in different dc magnetic fields [5]. Assuming a resonance separation of 622 MHz (corresponding to our tapered shim), the bandpass of the maser looks as shown in Fig.…”

“…4 as a function of magnetic field for this orientation. Population inversion is achieved by push-pull pumping the 1-3 and the 2-4 transitions [5]. The signal transition is the 2-3 transition.…”