The temperature dependence of the generation linewidth for an auto-oscillatorwith a nonlinear frequency shift is calculated. It is shown that the frequencynonlinearity creates a finite correlation time, tau, for the phasefluctuations. In the low-temperature limit in which the spectral linewidth issmaller than 1/tau, the line shape is approximately Lorentzian and thelinewidth is linear in temperature. In the opposite high-temperature limit inwhich the linewidth is larger than 1/tau, the nonlinearity leads to an apparent"inhomogeneous broadening" of the line, which becomes Gaussian in shape and hasa square-root dependence on temperature. The results are illustrated for thespin-torque nano-oscillator.
展开▼
