High-speed continuously tunable liquid crystal filter for WDM networks
High-speed continuously tunable liquid crystal filter for WDM networks
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用于 WDM 网络的高速连续可调液晶滤波器
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
K. Johnson
中科院分区：
文献类型：
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作者：
A. Sneh;K. Johnson
我们描述了一种高速波长可调谐液晶滤波器，它可以用作波分多址（WDMA）光网络接收端的调谐元件。该滤波器使用手性近晶A电斜液晶作为法布里-珀罗标准具中的有源腔材料，以获得微秒级的切换速度。使用市售的 BDH764E 液晶材料，我们展示了体法布里-珀罗和光纤法布里-珀罗 (FFP) 配置的可调谐光学滤波器。在 FFP 配置中获得了约 0.7 mm 的带宽和 70 的有效精度。在 1.55 /spl mu/m 的工作波长下测得 FFP 调谐范围为 13 nm，切换时间小于 10 /spl mu/s。给出了 FFP 配置中预期滤波器性能的理论分析。法布里-珀罗腔中的衍射被认为是主要的损耗因素，导致吞吐量降低和精细度变宽。理论上计算，当镜面精度为200、液晶腔厚度为5/spl mu/m时，可实现130的有效精度和2.2dB的吞吐量损失。假设空腔中包含短波导件。已经计算了 FFP 配置中滤波器的其他预期损耗源，显示对滤波器性能的影响可以忽略不计。
We describe a high-speed wavelength tunable liquid crystal filter which can be utilized as the tuning element at the receiving end of wavelength division multiaccess (WDMA) optical networks. The filter uses chiral smectic A electroclinic liquid crystals as the active cavity material in a Fabry-Perot etalon in order to obtain a microsecond switching speed. Using the commercially available BDH764E liquid crystal material, we demonstrate a tunable optical filter both in a bulk Fabry-Perot and a fiber Fabry-Perot (FFP) configuration. A bandwidth of about 0.7 mm and effective finesse of 70 were obtained in the FFP configuration. A FFP tuning range of 13 nm with a switching time of less than 10 /spl mu/s were measured at the operating wavelength of 1.55 /spl mu/m. A theoretical analysis of the expected filter performance in the FFP configuration is given. Diffraction in the Fabry-Perot cavity is identified as the dominant loss factor, resulting in reduced throughput and finesse broadening. It is calculated theoretically that an effective finesse of 130 and a throughput loss of 2.2 dB are achievable for a mirror finesse of 200 and a liquid crystal cavity thickness of 5 /spl mu/m. A short waveguide piece is assumed to be included in the cavity. Other expected loss sources for the filter in the FFP configuration have been calculated, showing negligible effect on the filter performance.