We report a theoretical model to design a stable and tunable optical frequency comb by controlling the periodic radiofrequency signal applied to the two cascaded lithium niobate Mach–Zehnder modulators. The spectrum flatness, frequency line spacing, and spectrum bandwidth depend on the periodic optical signal’s shape, periodicity, and duty cycle. So the shape and duty cycle of the optical signal are controlled by controlling the amplitude and phase of the periodic radiofrequency signal and realizing a 2.1% duty-cycled periodic signal, resulting in a 1.92-dB flat and 2.31-THz broad-spectrum optical frequency comb. The duty cycle of the optical signal is decreased by controlling the modulators in such a way that it will give the output signal for the transition period of the radiofrequency signal only. The line spacing is controlled by controlling the frequency of the radiofrequency signal and realizes a 30-GHz channel spaced frequency comb. The comb’s channel spacing and frequency can also be controlled by controlling the periodicity of radiofrequency signal and seed laser frequency, making the frequency comb tunable.

中文翻译：

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基于级联电光强度调制器的2.31-THz宽光频梳发生器的理论模型

我们报告了一个理论模型，通过控制应用于两个级联铌酸锂 Mach-Zehnder 调制器的周期性射频信号来设计稳定且可调谐的光频梳。频谱平坦度、频率线间距和频谱带宽取决于周期性光信号的形状、周期和占空比。因此通过控制周期射频信号的幅度和相位，实现2.1%占空比的周期信号来控制光信号的形状和占空比，从而得到1.92-dB平坦和2.31-THz的广谱光频梳子。通过以这样的方式控制调制器来降低光信号的占空比，使得它仅在射频信号的过渡周期给出输出信号。通过控制射频信号的频率来控制线间距，实现30GHz信道间隔频率梳。还可以通过控制射频信号和种子激光频率的周期性来控制梳的通道间距和频率，使频率梳可调。