Department of Photonics, National Cheng Kung University, Tainan, Taiwan.
Opt Lett. 2013 Sep 1;38(17):3355-8. doi: 10.1364/OL.38.003355.
For radio-over-fiber links, microwave-modulated optical carriers with high optical modulation depth are preferred because high optical modulation depth allows generation of high microwave power after photodetection, leading to high detection sensitivity, long transmission distance, and large link gain. This study investigates the period-one nonlinear dynamics of semiconductor lasers for optical modulation depth improvement to achieve photonic microwave amplification through modulation sideband enhancement. In our scheme, only typical semiconductor lasers are required as the amplification unit. The amplification is achieved for a broad microwave range, from less than 25 GHz to more than 60 GHz, and for a wide gain range, from less than 10 dB to more than 30 dB. The microwave phase quality is mainly preserved while the microwave power is largely amplified, improving the signal-to-noise ratio up to at least 25 dB. The bit-error ratio at 1.25 Gbits/s is better than 10(-9), and a sensitivity improvement of up to at least 15 dB is feasible.
对于光纤中的无线电链路，优选使用具有高光学调制深度的微波调制光载波，因为高光学调制深度允许在光电探测后产生高微波功率，从而实现高检测灵敏度、长传输距离和大链路增益。本研究调查了半导体激光器的周期-1 非线性动力学，以通过调制边带增强来实现光调制深度的提高，从而实现光子微波放大。在我们的方案中，仅需要典型的半导体激光器作为放大单元。放大可以在很宽的微波范围内实现，从小于 25 GHz 到大于 60 GHz，并且在很宽的增益范围内实现，从小于 10 dB 到大于 30 dB。在大幅放大微波功率的同时，主要保留了微波相位质量，将信噪比提高了至少 25 dB。在 1.25 Gbits/s 时的误码率优于 10(-9)，并且可以实现至少 15 dB 的灵敏度提高。
