Spontaneous locking of the phase of a coherent phonon source to an external reference is demonstrated in a deeply sideband-unresolved optomechanical system. The high-amplitude mechanical oscillations are driven by the anharmonic modulation of the radiation pressure force that result from an absorption-mediated free-carrier/temperature limit cycle, i.e., self-pulsing. Synchronization is observed when the pump laser driving the mechanical oscillator to a self-sustained state is modulated by a radiofrequency tone. We employ a pump-probe phonon detection scheme based on an independent optical cavity to observe only the mechanical oscillator dynamics. The lock range of the oscillation frequency, i.e., the Arnold tongue, is experimentally determined over a range of external reference strengths, evidencing the possibility to tune the oscillator frequency for a range up to 350 kHz. The stability of the coherent phonon source is evaluated via its phase noise, with a maximum achieved suppression of 44 dBc/Hz at 1 kHz offset for a 100 MHz mechanical resonator. Introducing a weak modulation in the excitation laser reveals as a further knob to trigger, control and stabilize the dynamical solutions of self-pulsing based optomechanical oscillators, thus enhancing their potential as acoustic wave sources in a single-layer silicon platform.

中文翻译：

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注入锁定在光机械相干声子源中

在深边带未解决的光力学系统中证明了相干声子源的相位自发锁定到外部参考。高振幅的机械振荡是由辐射压力的非谐调制驱动的，该调制是由吸收介导的自由载流子/温度极限循环（即自脉冲）引起的。当将机械振荡器驱动至自持状态的泵浦激光器通过射频音调进行调制时，可以观察到同步。我们采用基于独立光学腔的泵浦声子声子检测方案，仅观察机械振荡器动力学。振荡频率的锁定范围（即Arnold舌头）是在一定范围的外部参考强度下通过实验确定的，证明有可能在高达350 kHz的范围内调谐振荡器频率。相干声子源的稳定性通过其相位噪声来评估，对于100 MHz机械谐振器，在1 kHz偏移下最大可实现44 dBc / Hz的抑制。在激发激光器中引入微弱的调制可以作为触发，控制和稳定基于自脉冲的光机械振荡器的动态解决方案的另一个旋钮，从而增强它们在单层硅平台中作为声波源的潜力。