Liquid Crystal Polarization Controller Arrays on Planar Lightwave Circuits(Joint Special Issue on Recent Progress in Optoelectronics and Communications)(OECC Awarded)

概要

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We have formed simple polarization-controller arrays by inserting liquid crystal (LC) in trenches cut across planar lightwave circuits (PLCs). We fabricated LC layers for use as polarization controllers on PLCs in two ways; in one, the ultra-thin layer of LC is held in a cell that is inserted into a trench on the PLC while in the other, the trench is directly filled with the LC. The ultra-thin LC cell can change the phase of 1.55-μm light from 0 to 3π while the LC filling can change the phase of light at the same wavelength from 0 to 12π below 5Vrms. Two former parallel-aligned ultra-thin LC cells, where the directions of alignment of the liquid crystals are rotated by 45° relative to each other, are capable of converting light with an arbitrary input polarization to TE or TM polarization. Ultra-thin cells of twisted nematic LC can switch the polarization between TE and TM modes with an extinction ratio of -15dB. The array we fabricated had a pitch of 1mm and 5 elements, but an array with more than 100 elements and a pitch below 125μm will easily be possible by using finely patterned transparent electrodes. We have also applied our techniques to the fabrication of LC-based variable optical attenuators (VOA) on the PLC.
社団法人電子情報通信学会の論文
2003-05-01