Photonic Generation of Microwave Waveforms Based on a Polarization Modulator in a Sagnac Loop
Photonic Generation of Microwave Waveforms Based on a Polarization Modulator in a Sagnac Loop
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DOI：
10.1109/jlt.2014.2312819
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发表时间：
2014-03
影响因子：
4.7
通讯作者：
Weilin Liu;J. Yao
中科院分区：
文献类型：
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作者：
Weilin Liu;J. Yao
提出了一种在Sagnac环中使用偏振调制器（PolM）的光微波波形发生器，并进行了实验验证。可以使用正弦信号来生成包括三角波形、正弦波和方波的微波波形，以在Sagnac环中的PolM处调制光波。在所提出的微波波形发生器中，正弦微波信号被施加到Sagnac环路中的PolM。由于速度失配，只有Sagnac环中的顺时针光波被PolM处的正弦微波信号有效地调制，而逆时针光波不被调制。沿着顺时针方向，可以通过在PolM之后调谐偏振控制器来分别控制奇数阶和偶数阶边带的功率。此外，通过在偏振分束器的输出处组合逆时针和顺时针光载波，可以独立地控制光载波的输出功率。结果，产生了具有可控的奇阶和偶阶边带的调制信号。通过将调制信号施加到光电探测器，产生具有完全可控的奇次和偶次谐波的微波信号，该信号对应于所需的微波波形。理论分析，这是通过实验验证。实验产生了重复频率可调范围为2 ~ 4 GHz的三角波、正弦波和方波。
An optical microwave waveform generator using a polarization modulator (PolM) in a Sagnac loop is proposed and experimentally demonstrated. Microwave waveforms including a triangular waveform, a sawtooth waveform, and a square waveform, can be generated using a sinusoidal signal to modulate a light wave at a PolM in a Sagnac loop. In the proposed microwave waveform generator, a sinusoidal microwave signal is applied to the PolM in the Sagnac loop. Due to the velocity mismatch, only the clockwise light wave in the Sagnac loop is effectively modulated by the sinusoidal microwave signal at the PolM, and the counter-clockwise light wave is not modulated. Along the clockwise direction, the powers of the odd- and even-order sidebands can be controlled separately by tuning a polarization controller after the PolM. In addition, the output power of the optical carrier can be independently controlled by combining the counter-clockwise and clockwise optical carriers at the output of a polarization beam splitter. As a result, a modulated signal with controllable odd- and even-order sidebands is generated. By applying the modulated signal to a photodetector, a microwave signal with fully controllable odd- and even-order harmonics is generated, which corresponds to a desired microwave waveform. A theoretical analysis is developed, which is validated by an experiment. A triangular, sawtooth, and square waveform with a repetition rate tunable from 2 to 4 GHz is experimentally generated.