Polymer-Stabilized Blue Phase and Its Application to a 1.5 µm Band Wavelength Selective Filter

Seiji Fukushima,Hirotsugu Kikuchi,Kakeru Tokunaga,Yasushi Okumura,Takuya Morishita,Hiroki Higuchi,Hidehisa Tazawa

doi:10.3390/cryst11091017

Seiji Fukushima, Hirotsugu Kikuchi + Show 5 more

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https://doi.org/10.3390/cryst11091017

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Abstract

The use of polymer-stabilized blue phase (PSBP) including a tolane-type liquid crystal was investigated to develop a voltage-controlled wavelength selective filter for wavelength-division-multiplexing optical fiber network. It was found that the tolane-type liquid crystal introduction can increase both a blue-phase temperature range and a Kerr coefficient. A Fabry–Perot etalon filled with PSBP functioned as a wavelength selective filter, as expected. The tuning wavelength range was 62 nm although peak transmission was not as high as expected. Numerical analysis suggested that light absorption in transparent electrodes may cause the issue. Minor change to the etalon structure will result in improved performance.

Highlights

A wavelength selective filter (WSF) has become an essential device in a wavelengthdivision-multiplexed (WDM) optical fiber communication system, where multiple color signals are transmitted in parallel in the optical fiber to increase communication throughput [1,2,3,4]
This paper focuses on the use of polymer-stabilized blue phase (PSBP) for a WSF
It was found that a tolane-type liquid crystal introduction can increase both the blue-phase temperature range and the Kerr coefficient

Summary

Introduction

A wavelength selective filter (WSF) has become an essential device in a wavelengthdivision-multiplexed (WDM) optical fiber communication system, where multiple color signals are transmitted in parallel in the optical fiber to increase communication throughput [1,2,3,4]. Current systems employ wavelengths between 1.3 and 1.6 μm as optical fibers show the smallest absorption and the smallest chromatic dispersion near these wavelengths. WDM systems could be developed by using constant wavelength filters while the systems employing the WSFs have more advantages in design flexibility, low-cost construction and maintenance, and functionality. System researchers and designers impose other requirements such as low-voltage operation, low-power consumption, fast response, and wide temperature range. It should be noted that the use of liquid crystal (LC) is advantageous in large change in refractive index and low-voltage and low-power operation [7]. Response times of nematic LC are typically in ms order some LC materials can respond in μs order [8]

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Discussion

Conclusion