An integrated nematic liquid crystal in-fiber modulator derivates from capillary optical fiber

A novel liquid crystal integrated modulation-depth-adjustable in-fiber modulator is proposed. The liquid crystal is encapsulated in a specially designed capillary optical fiber with tubular structure. The experimental results show that the liquid crystal under the electric field can influence the light intensity in the tubular core of the fiber. The light at 632.8 nm in the circular waveguide can be modulated by only 2.71×10−2 nL of the liquid crystals under electric field. The wide range of modulation-depth from 23% to 50% can be obtained by adjusting the strength of the external electric field. In addition, the modulator shows good stability and repeatability. This work has great potentials in integrated in-fiber optical devices such as tunable modulators, optical switches and electric field sensors.