Hsieh Kun-Lin, Hwang Sheng-Kwang, Yang Chin-Lung
Opt Lett. 2017 Sep 1;42(17):3307-3310. doi: 10.1364/OL.42.003307.
This study numerically and experimentally investigates a photonic approach for microwave time delay, which takes advantage of the redshift of the laser cavity resonance induced by external optical injection in a semiconductor laser. The strong enhancement around the redshifted cavity resonance not only amplifies the power, but also shifts the phase of the microwave signals carried by the optical injection. Such a microwave phase shift is approximately linear over a few gigahertz, leading to a constant microwave time delay over the frequency range. A different time delay can be achieved by simply adjusting the injection power or frequency. For the microwave frequencies up to 40 GHz investigated in this Letter, a continuously tunable range of more than 80 ps in time delay is achieved over an instantaneous bandwidth of approximately 7 GHz. The quality of the data carried by the microwave signals is mostly preserved after time delay. Thus, a bit-error ratio down to 10 at 2.5 Gb/s is achieved with a possible detection sensitivity improvement of 5 dB.
本研究通过数值模拟和实验研究了一种用于微波时间延迟的光子学方法，该方法利用了半导体激光器中外部光注入引起的激光腔共振红移。红移腔共振附近的强烈增强不仅放大了功率，还改变了光注入所携带微波信号的相位。这种微波相移在几吉赫兹范围内近似呈线性，导致在该频率范围内微波时间延迟恒定。通过简单地调整注入功率或频率，可以实现不同的时间延迟。对于本信函中研究的高达40 GHz的微波频率，在约7 GHz的瞬时带宽内实现了超过80 ps的连续可调时间延迟范围。微波信号携带的数据质量在时间延迟后大多得以保留。因此，在2.5 Gb/s时实现了低至10的误码率，并且检测灵敏度可能提高5 dB。
