Two methods are studied for reducing the polarization dependence of a tunable liquid-crystal Fabry-Perot interferometer filter (LC-FPI). One uses a twisted nematic (TN) liquid-crystal in a Fabry-Perot cavity. We have theoretically explained that the twist angle should be π/2 + mπ(m = 0, 1, 2, ⋯) to eliminate the polarization dependency. An approximate 5 nm polarization-independent tuning with a π/2 TN LC-FPI cell was achieved. The other uses a polarization diversity configuration. We have fabricated a polarization-independent LC-FPI filter module with a Faraday rotator using polarization diversity double-pass configuration. This filter module has a 3 dB bandwidth of less than 0.5 nm, a 15 dB bandwidth of 1.7 nm, and a polarization-dependent loss (PDL) of 0.8 dB. The filter module was utilized in 10 Gbit/s transmission experiments to confirm its feasibility.
|ジャーナル||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|出版ステータス||Published - 1996 4月|
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