Delayed Feedback Dynamics of Liénard-type RTD-Photo-Detector Optoelectronic Oscillators

We use nonlinear dynamics approach for studying delayed feedback optoelectronic oscillators (OEOs) formed by hybrid integration of resonant tunneling diode (RTD) photodetectors with laser diodes, in both single and dual optical fiber feedback routes. In the single loop topology the performance of the RTD-OEO free-running self-sustained oscillator is improved in terms of phase noise, with a compromise between the delay line and the strength of the optical re-injection. In the dual loop configuration superior performance is achieved due to the suppression of the side modes associated with the optical cavity length resulting in a side mode suppression ratio up to -60 dBc of the carrier frequency. We compare experimental results with numerical simulations based upon a system of delay differential equations comprising a Liénard oscillator model driven by white Gaussian noise and coupled with laser rate equations. The delayed feedback Liénard oscillator model gives considerable insight into the RTD-OEO dynamical regimes predicting its main features in both single and dual loop configurations.