Unidirectional light emission in PT-symmetric microring lasers
Unidirectional light emission in PT-symmetric microring lasers
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DOI：
10.1364/oe.26.027153
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发表时间：
2018-10-15
期刊：
影响因子：
3.8
通讯作者：
Khajavikhan, Mercedeh
中科院分区：
文献类型：
--
作者：
Ren, Jinhan;Liu, Yuzhou G. N.;Khajavikhan, Mercedeh
在奇偶时间对称耦合腔中，增益和损耗的协同使用导致了单模激光运转。然而，在相应的共振频率下，理想的环形谐振器倾向于支持两个简并的本征模，沿着腔以相反的方向传播。在这里，我们展示了一种单向单模奇偶时间对称激光器，它通过在环形腔中加入具有相反手征性的有源S弯曲结构来实现。这种手性元件通过在顺时针(CW)和逆时针(CCW)行进模式之间提供非对称耦合，打破了环腔的旋转对称性，从而创造了一种新的例外点。因此，这一性质导致抑制其中一个反向传播模式。在本文中，我们首先测量了存在S弯曲波导的单环谐振器中顺波和逆时模之间的消光比。然后，我们在实验上研究了PT对称系统中例外点以下和上方的单向辐射。最后，在两个S弯曲环形谐振器通过链接结构耦合的系统中显示了单向辐射。(C)2018年OSA开放获取出版协议条款下的美国光学学会
The synergetic use of gain and loss in parity-time symmetric coupled resonators has been shown to lead to single-mode lasing operation. However, at the corresponding resonance frequency, an ideal ring resonator tends to support two degenerate eigenmodes, traveling along the cavity in opposite directions. Here, we show a unidirectional single-moded parity-time symmetric laser by incorporating active S-bend structures with opposite chirality in the respective ring resonators. Such chiral elements break the rotation symmetry of the ring cavities by providing an asymmetric coupling between the clockwise (CW) and the counterclockwise (CCW) traveling modes, hence creating a new type of exceptional point. This property, consequently, leads to the suppression of one of the counter-propagating modes. In this paper, we first measure the extinction ratio between the CW and CCW modes in a single ring resonator in the presence of an S-bend waveguide. We then experimentally investigate the unidirectional emission in PT-symmetric systems below and above the exceptional point. Finally, unidirectional emission will be shown in systems of two S-bend ring resonators coupled through a link structure. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement