グラフェンの歪みナノ構造のプラズモニクス開拓およびそのセンシングへの応用

双纳米脊的解析模型比较简单。我们模拟了双脊发射的SPP波是单脊发射的SPP波相互干涉的结果，这一点已经讨论过了。由于等离子体波沿着石墨烯-空气界面传播，因此出现该相位延迟。当等离子体波在脊上传播时，它必须遵循脊曲线，导致与平坦石墨烯相比的额外行进长度。这个延迟可以从右曲线长度和脊下直线之间的差解析计算。通过数值模拟（未示出）验证了相位延迟的存在，数值模拟结果与解析结果吻合较好。对于右侧，从100 nm处发射的SPP波在与从150 nm处发射的SPP波发生干涉之前，经历了从150 nm处发射的SPP波的相位延迟。对于左侧，从150 nm脊发射的SPP波也从100 nm脊得到相位延迟。然而，两个相位延迟是不相等的。因此，在每一侧的干扰是不同的，导致不对称的定向等离子体激元发射。从该图中，可以选择提供等离子体激元发射的强方向性的条件。然后，我们使用条件（275 nm脊分离）进行模拟。实现了定向等离子体激元发射。还实现了波长分类发射（相同结构，SPP波根据波长向左侧或右侧行进）。

The analytic model for double nanoridge is simple. We model that the SPP wave launched from double nanoridge is just interference result of SPP wave launched by each single ridge, which is already discussed. This phase delay occurs because plasmon wave travel along graphene-air interface. When the plasmon wave propagate over ridge, it must follow the ridge curve, resulting in an extra travelling length compared to that of flat graphene. This delay can be calculated analytic from the difference between right curve length and the straight line under the ridge. We also did the simulation (not shown here) to confirm this phase delay, and the numerical result match the analytic result.For the right side, the SPP wave launched from 100-nm experienced phase delay from 150-nm ridge before interferes with another SPP wave launched from 150-nm ridge. For the left side, the SPP wave launched from 150-nm ridge also got phase delay from 100-nm ridge. However, the two phase delays are not equal. Therefore, the interference on each side is different, resulting in asymmetric directional plasmon launching.The ratio of right/left launched amplitude from the analytic model was shown. From this graph, one can choose the condition which provide strong directionality of the plasmon launching. We then use the condition (275 nm ridge separation) to perform simulation. Directional plasmon launching is achieved. Wavelength-sorted launching (same structure, SPP wave goes to left or right side depending on wavelength), is also achieved.