Millimeter-Wave Frequency Synthesizer Using Dual Microcomb Photomixing

The patent replaces conventional electronic frequency synthesis with photonic frequency synthesis using microcomb-based photomixing. Optical microcombs generated in microresonators are mixed in the optical domain to generate millimeter-wave signals, substituting electronic oscillators and harmonics generators with optical frequency combs and photodetectors. This substitution enables extended tuning range beyond electronic limits while reducing phase noise through the inherent stability of optical frequency references.

The patent changes the fundamental operating parameters from electronic frequencies to optical frequencies. By using optical microcombs with repetition rates in the hundreds of GHz range and mixing different comb lines, the system achieves millimeter-wave generation with tuning ranges exceeding 100 GHz, far beyond conventional electronic synthesizers. The parameter change from electronic to optical domain fundamentally resolves the tuning range limitation.

The patent substitutes electronic frequency generation with optical frequency comb generation and photomixing. Optical microcombs provide stable frequency references that can be traced to atomic clocks or other stable frequency standards. The photomixing process generates millimeter-wave signals with stability determined by the optical comb references rather than electronic oscillator drift, achieving superior frequency stability at high frequencies where electronic synthesizers fail.

The patent introduces optical frequency combs as intermediary carriers to transfer frequency stability from optical references to millimeter-wave signals. The microcomb lines serve as stable intermediaries that bridge the gap between low-frequency stable references and high-frequency millimeter-wave generation, enabling accurate frequency synthesis at frequencies where direct electronic generation is unstable.

The patent uses universal microresonator structures that can generate microcombs with different repetition rates and frequency offsets using the same basic device architecture. By designing microresonators with controllable parameters (such as radius, thickness, and material composition) that can be tuned during or after fabrication, the system achieves the required frequency differentiation without requiring extremely tight manufacturing tolerances on each individual device, thus reducing the effective precision burden.

The patent implements feedback control mechanisms to compensate for manufacturing variations in chip-scale microresonators. By monitoring the actual microcomb frequencies generated and applying feedback tuning (through thermal, mechanical, or electrical means), the system corrects for fabrication tolerances and achieves the required frequency precision despite variations in microresonator dimensions caused by standard semiconductor manufacturing processes.