Priel Maayan, Kumar Bag Saawan, Slook Matan, Dokhanian Leroy, Shafir Inbar, Hen Mirit, Katzman Moshe, Grunwald Etai, Munk Dvir, Feldberg Moshe, Sharabani Tali, Inbar Naor, Bashan Gil, Zadok Avi
Opt Express. 2023 Jan 2;31(1):684-697. doi: 10.1364/OE.477334.
Opto-electronic oscillators are sources of microwave-frequency tones that may reach very low noise levels. Much effort is being dedicated to the realization of oscillators based on photonic integrated devices. In this work, we propose and demonstrate a thermo-elastic opto-electronic oscillator at 2.213 GHz frequency based on a standard silicon-photonic integrated circuit. A microwave-frequency electrical signal modulates an optical pump wave carrier. The modulated waveform launches surface acoustic waves in a silicon-on-insulator substrate, through absorption in a metallic grating and thermo-elastic actuation. The waveform is reconverted to the optical domain through photoelastic modulation of an optical probe wave carrier in a standard racetrack resonator waveguide. Both the thermo-elastic actuation and the photoelastic modulation are radio-frequency selective. The output probe wave is detected, and the receiver voltage is amplified and fed back to modulate the optical pump input. Sufficient gain drives the loop into oscillations. The oscillator does not involve piezoelectricity and can be realized on any substrate. Long acoustic delays may be implemented in compact devices. The frequency of operation is scalable to tens of GHz. The principle may be useful in integrated microwave-photonic signal processing and in the elastic analysis of surfaces and thin layers.
光电振荡器是微波频率信号源，其噪声水平可能极低。目前人们正致力于基于光子集成器件实现振荡器。在这项工作中，我们提出并演示了一种基于标准硅光子集成电路的2.213GHz频率的热弹性光电振荡器。微波频率的电信号调制光泵浦波载波。调制后的波形通过金属光栅中的吸收和热弹性驱动，在绝缘体上硅衬底中激发表面声波。该波形通过标准跑道谐振器波导中光探测波载波的光弹调制重新转换到光域。热弹性驱动和光弹调制都是射频选择性的。检测输出探测波，放大接收器电压并反馈以调制光泵浦输入。足够的增益驱动环路进入振荡状态。该振荡器不涉及压电效应，可在任何衬底上实现。长声学延迟可在紧凑的器件中实现。工作频率可扩展到数十GHz。该原理可能在集成微波光子信号处理以及表面和薄层的弹性分析中有用。
