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Optoelectronic oscillators (OEOs), realized on photonic integrated circuits (PICs), have the potential of producing millimeter-wave (mm-wave) clock signals with lower timing jitter and higher operating frequencies than their all-electronic counterparts. To have a proper design tool for these PIC-based OEOs, a novel, computationally efficient time-domain circuit simulation model is presented. It relies on describing the propagation, filtering and mixing of the spectral contents of the circulating optical and mm-waves. This work specifically targets OEOs consisting of building blocks offered by commercial PIC platforms, such as high-speed modulators, high-Q filters, semiconductor optical amplifiers (SOAs) and high-speed photodetectors (PDs). The model can simulate a wide range of OEO topologies, including OEOs that use an array of SOAs and PDs to boost the generated mm-wave signal power, or OEOs that employ modulator configurations other than the often-used Mach-Zehnder devices. The model also takes into account the saturation effects and noise of the SOAs and PDs, as well as all the propagation losses and delays experienced by the optical and mm-waves, which allows for investigating the effects of fabrication errors. As a test case, this model is applied to a proposed design of a hybridly integrated 20-GHz OEO, which relies on a combination of indium phosphide (InP) and silicon nitride (SiN) based PICs, using realistic parameters representative for these platforms. Timing jitters of almost 100 fs (10 kHz { 10 MHz) are demonstrated by optimising the SOA gain and the laser frequency detuning from the high-Q filter resonances.
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