Mori Daisuke, Baba Toshihiko
Opt Express. 2005 Nov 14;13(23):9398-408. doi: 10.1364/opex.13.009398.
Previously, we discussed an optical delay device consisting of a directional coupler of two different photonic crystal (PC) waveguides. It generates wideband and low dispersion slow light. However, it is easily degraded by a large reflection loss for a small imperfection of the coupling condition. In this paper, we propose and theoretically discuss a PC coupled waveguide, which allows more robust slow light with lower loss. For this device, unique photonic bands with a zero or negative group velocity at the inflection point can be designed by the structural tuning. Finite difference time domain simulation demonstrates the stopping and/or back and forth motion of an ultrashort optical pulse in the device combined with the chirped structure. For a signal bandwidth of 40 GHz, the average group index of the slow light will be 450, which gives a 1 ns delay for a device length of 670 microm. The theoretical total insertion loss at the device and input/output structures is as low as 0.11 dB.
此前，我们讨论了一种由两个不同光子晶体（PC）波导的定向耦合器组成的光学延迟装置。它能产生宽带且低色散的慢光。然而，对于耦合条件的微小缺陷，它很容易因较大的反射损耗而性能下降。在本文中，我们提出并从理论上讨论了一种PC耦合波导，它能实现损耗更低、更稳定的慢光。对于该装置，通过结构调谐可以设计出在拐点处具有零或负群速度的独特光子带。时域有限差分模拟表明，结合啁啾结构，超短光脉冲在该装置中会停止和/或来回移动。对于40 GHz的信号带宽，慢光的平均群折射率将为450，这意味着对于670微米长的装置，延迟为1 ns。该装置及输入/输出结构的理论总插入损耗低至0.11 dB。
