Dong Po
Opt Express. 2015 Apr 20;23(8):10498-505. doi: 10.1364/OE.23.010498.
On-chip optical isolators not requiring the use of magneto-optical materials has become a long-standing challenge in integrated optics. Here, we demonstrate that a traditional travelling-wave modulator can effectively function as an optical isolator, when driven under a prescribed modulation condition. By using an off-shelve lithium niobate modulator, we achieve more than 12.5 dB isolation over an 11.3-THz bandwidth at telecommunication wavelengths with a fiber-to-fiber insertion loss of 5.5 dB, by employing only a single radio-frequency drive signal. We also verify that the proposed active isolator can be functional in a laser system to effectively prevent instability due to strong back reflections. Since travelling-wave modulators are common devices in III-V and silicon photonics, our simple but efficient architecture may provide a practical solution to non-reciprocal light routing in photonic integrated circuits.
无需使用磁光材料的片上光学隔离器一直是集成光学领域的一项长期挑战。在此，我们证明，在规定的调制条件下驱动时，传统的行波调制器可以有效地起到光学隔离器的作用。通过使用一个现成的铌酸锂调制器，我们仅采用单个射频驱动信号，就在电信波长的11.3太赫兹带宽上实现了超过12.5分贝的隔离度，光纤到光纤的插入损耗为5.5分贝。我们还验证了所提出的有源隔离器在激光系统中能够有效发挥作用，以防止因强烈的背向反射而导致的不稳定性。由于行波调制器是III-V族和硅光子学中的常见器件，我们这种简单而高效的架构可能为光子集成电路中的非互易光路由提供一种切实可行的解决方案。
