Improvement on tandem-type ultra-high-density multi/demultiplexer performance for use in future super-dense photonic network

我们的目的是降低串联型超高密度多路复用器中使用的一次和二次AWG的串扰，方法是在紫外光下通过金属掩模引起折射率变化。1.金属掩模制造工艺：我们提出了一种金属掩模制造工艺，使用喷墨打印机绘制掩模图形，并使用复印机将其固定在抗蚀剂上。这种方法的优点是制作过程短，成本较低。2.初级AWG的相位误差测量：我们发现，当所用光源仅覆盖AWG透射谱中连续两个峰值的两个窄谱区域时，由光学低相干涉术获得的AWG干涉图被分解。它被成功地用于测量1μ间隔的初级AWG的相位误差分布，其中来自1.3THzmLED和1.5THzmLED的光被组合在一起，用两个峰值覆盖光谱。我们利用相位误差数据制作了AWG的金属掩模，并成功地将频谱中的旁瓣降低了7分贝。3.二次AWG的相位误差测量：我们成功地在频域内测量了窄通道间隔AWG的相位误差分布，测量精度为0.05rad。这是通过扫描50 nm/S的激光频率和采用平衡检测方案去除激光强度噪声来实现的。4.超高密度串联式多路/解复用器的制作：采用上述工艺制作了二次AWG的金属掩模，并成功地将中心阵列波导周围的旁瓣串扰降低到-39dB。通过将它们与相位补偿的初级AWG相结合，1000路多路/解复用器的累积串扰比以前报道的系统降低了5dB。

Our aim was to reduce the crosstalk of primary and seconday AWGs used in a tandem-type ultra-high density multi/demultiplexer by means of photoinduced refractive index change under UV laser light through metal masks.1.Metal mask fabrication process : We proposed a metal mask fabrication process employing an inkjet printer to draw the mask pattern and a copy machine to fix it on a resist sheet. The advantage of the method is a short fabrication process for around 10 minutes and a lower cost.2.Phase error measurement of primary AWG : We found that an interferogram obtained from an AWG with optical low coherence interferometry is decomposed when the employed light source covers only two narrow spectral regions at two successive peaks in its AWG transmission spectrum. This was utilized successfully for measuring the phase error distribution of a 1-THz-spaced primary AWG, where the lights from 1.3 and 1.5 μm LEDs were combined to cover the spectrum with two peaks. We fabricate the metal mask for the AWG from the phase error data and succeeded in reducing the sidelobe in the spectrum by 7 dB.3.Phase error measurement of secondary AWGs : We have succeeded in measuring the phase error distributions of narrow-channel spacing AWGs with an accuracy of 0.05 rad in the frequency domain. This was achieved by sweeping the laser frequency at 50nm/s and by removing the laser intensity noise with a balanced detection scheme.4.Reduction of an ultra-high density tandem multi/demultiplexer : We fabricated metal masks for the secondary AWGs with the above fabrication process and succeeded in reducing the sidelobe crosstalk to -39 dB around their central arrayed waveguides. By combing them with the phase-compensated primary AWG, the accumulated crosstalk of the 1000-channel multi/demultiplexer was reduced by 5 dB as compared with the system previously reported.