Steed Robert J, Pozzi Francesca, Fice Martyn J, Renaud Cyril C, Rogers David C, Lealman Ian F, Moodie David G, Cannard Paul J, Lynch Colm, Johnston Lilianne, Robertson Michael J, Cronin Richard, Pavlovic Leon, Naglic Luka, Vidmar Matjaz, Seeds Alwyn J
Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE, UK.
Opt Express. 2011 Oct 10;19(21):20048-53. doi: 10.1364/OE.19.020048.
We present results for an heterodyne optical phase-lock loop (OPLL), monolithically integrated on InP with external phase detector and loop filter, which phase locks the integrated laser to an external source, for offset frequencies tuneable between 0.6 GHz and 6.1 GHz. The integrated semiconductor laser emits at 1553 nm with 1.1 MHz linewidth, while the external laser has a linewidth less than 150 kHz. To achieve high quality phase locking with lasers of these linewidths, the loop delay has been made less than 1.8 ns. Monolithic integration reduces the optical path delay between the laser and photodiode to less than 20 ps. The electronic part of the OPLL was implemented using a custom-designed feedback circuit with a propagation delay of ~1 ns and an open-loop bandwidth greater than 1 GHz. The heterodyne signal between the locked slave laser and master laser has phase noise below -90 dBc/Hz for frequency offsets greater than 20 kHz and a phase error variance in 10 GHz bandwidth of 0.04 rad2.
我们展示了一种外差式光学锁相环（OPLL）的结果，该锁相环与外部鉴相器和环路滤波器单片集成在磷化铟（InP）上，它将集成激光器锁相到外部源，可在0.6吉赫兹至6.1吉赫兹之间调谐偏移频率。集成半导体激光器在1553纳米波长处发射，线宽为1.1兆赫兹，而外部激光器的线宽小于150千赫兹。为了用这些线宽的激光器实现高质量锁相，环路延迟已被控制在小于1.8纳秒。单片集成将激光器和光电二极管之间的光程延迟减小到小于20皮秒。OPLL的电子部分采用定制设计的反馈电路实现，其传播延迟约为1纳秒，开环带宽大于1吉赫兹。对于大于20千赫兹的频率偏移，锁定的从激光器和主激光器之间的外差信号具有低于-90分贝/赫兹的相位噪声，并且在10吉赫兹带宽内的相位误差方差为0.04弧度平方。
