Photonic Liquid Crystal Fibers Research Articles

Voltage, thermal and magnetic field fiber sensors based on magnetic nanoparticles-doped photonic liquid crystal fibers.

In this article, highly sensitive voltage, thermal and magnetic field fiber sensors were obtained in magnetic nanoparticles-doped E7 liquid crystals filled into photonic crystal fibers (PLCF). The voltage and temperature sensitivity reached at 12.598 nm/V and -3.874 nm/°C, respectively. The minimum voltage response time is 48.2 ms. The phase transition temperature Tc of liquid crystal with magnetic dopant was reduced from 60 °C to 46 °C. The magnetic field sensor based on magnetic nanoparticles-doped PLCF were obtained with sensitivity of 118.2 pm/mT from 400 to 460 mT.

Frequency dependence of electric field tunability in a photonic liquid crystal fiber based on gold nanoparticles-doped 6CHBT nematic liquid crystal

In this paper, we investigate an external electric field frequency influence on a photonic liquid crystal fiber (PLCF) based on a gold nanoparticles (NPs)-doped nematic liquid crystal (LC) and its response to the external electric field. We used a 6CHBT nematic LC doped with 2-nm gold NPs in a weight concentration of 0.1%, 0.2%, 0.3%, and 0.5%. Full Text: PDF ReferencesJ. C. Knight, T. A. Birks, P. St. J. Russell, and D. M. Atkin, "All-silica single-mode optical fiber with photonic crystal cladding," Opt. Lett. 21, 1547-1549 (1996) CrossRef J. C. Knight,T. A. Birks, P. S. J.Russell, , and J. P. De Sandro, "Properties of photonic crystal fiber and the effective index model", JOSA A, 15(3), 748-752, (1998) CrossRef S. A. Cerqueira,F. Luan, C. M. B. Cordeiro, A. K. George, and J. C. Knight, "Hybrid photonic crystal fiber", "Optics Express", 14(2), 926-931,(2006) CrossRef W. Bragg, "Liquid Crystals", Nature 133, 445-456, (1934) https://doi.org/10.1038/133445a0 CrossRef J. Kędzierski, K. Garbat, Z. Raszewski, M. Kojdecki, K. Kowiorski, L. Jaroszewicz, and W. Piecek, "Optical properties of a liquid crystal with small ordinary and extraordinary refractive indices and small optical anisotropy", Opto-Electronics Review, 22(3), 162-165, (2014) CrossRef Y. Li, and S. T. Wu, "Polarization independent adaptive microlens with a blue-phase liquid crystal", Optics express, 19(9), 8045-8050, (2011) CrossRef T. Woliński, S. Ertman, K. Rutkowska, D. Budaszewski, M. Sala-Tefelska, M. Chychłowski, K. Orzechowski, K. Bednarska, P. Lesiak, "Photonic Liquid Crystal Fibers - 15 years of research activities at Warsaw University of Technology", Phot. Lett. Pol., (11), (2), 22-24, (2019) https://doi.org/10.4302/plp.v11i2.907. CrossRef T.T. Larsen, A. Bjraklev, D.S. Hermann, J. Broeng, Opt. Expr. 11(20), 2589, (2003) CrossRef T.R. Woliński, K. Szaniawska, K. Bondarczuk, P. Lesiak, A.W. Domański, R. Dąbrowski, E. Nowinowski-Kruszelnicki, J. Wójcik, "Propagation properties of photonic crystal fibers filled with nematic liquid crystals", Opto-Electron. Rev. 13(2), 59 (2005) DirectLink L. Scolari, S. Gauza, H. Xianyu, L. Zhai, L. Eskildsen, T. T. Alkeskjold, S.-T. Wu, and A. Bjarklev, "Frequency tunability of solid-core photonic crystal fibers filled with nanoparticle-doped liquid crystals," Opt. Express 17(5), 3754-3764 (2009). CrossRef A. Siarkowska, M. Chychłowski, D. Budaszewski, B. Jankiewicz, B. Bartosewicz, and T. R. Woliński, "Thermo-and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles", Beilstein Journal of Nanotechnology, 8(1), 2790-2801, (2017) CrossRef D. Budaszewski, M. Chychłowski, A. Budaszewska, B. Bartosewicz, B. Jankiewicz, and T. R. Woliński, "Enhanced efficiency of electric field tunability in photonic liquid crystal fibers doped with gold nanoparticles", Optics express, 27(10), 14260-14269, (2019) CrossRef D. Budaszewski, A. Siarkowska, M. Chychłowski, B. Jankiewicz, B. Bartosewicz, R. Dąbrowski, T. R. Woliński, "Nanoparticles-enhanced photonic liquid crystal fibers", Journal of Molecular Liquids, 267, 271-278, (2018) CrossRef

All-Optical Directional Control of Emission in a Photonic Liquid Crystal Fiber Laser

This study investigates the all-optical directional control of emission in a cholesteric liquid crystal (CLC)-infiltrated photonic crystal fiber (PCF) laser. A laser dye-doped CLC (LD-CLC) and an azobenzene LC-doped CLC (ALC-CLC), which are selectively infiltrated into the hollow core and holey-matrix cladding of the PCF, function as an optically active cavity and an all-optical emission direction-controllable light valve, respectively, in the photonic LC fiber (PLCF) laser. Experimental results show that the PLCF has a low energy threshold (approximately 63 nJ/pulse) and a large circular polarization anisotropy (g ≅ 2) in lasing output. The lasing output from the LD-CLC-filled core of the PLCF can be all-optical controlled to emit omni- or semi-directionally or to off-emit by controlling the isothermal phase transition of the CLC between the scattering focal conic state and the transparent isotropic state by the all-optical-induced reversible photoisomerization of the doped ALCs in the cladding region. The emission direction-controllable PLCF laser has significant potential in various applications, such as bio-image, photo-therapy, wearable devices, displays, sensors, and lighting.

Photonic Liquid Crystal Fibers – 15 years of research activities at Warsaw University of Technology

Photonic Liquid Crystal Fibers – 15 years of research activities at Warsaw University of Technology

Enhanced efficiency of electric field tunability in photonic liquid crystal fibers doped with gold nanoparticles.

In this paper, we present our recent research results on light propagation in photonic crystal fibers (PCFs) infiltrated with a 6CHBT nematic liquid crystal (LC) doped with 2-nm gold nanoparticles (NPs) with a concentration in the range of 0.01 - 0.5% wt. Electro-optical response times and thermal tuning of the investigated samples have been studied in detail. We have observed up to ~80% decrease of rise times for different concentrations of gold NPs in the LC. Moreover, a significant reduction of the Fréedericksz threshold voltage (up to 60%) has been observed for samples with higher concentrations of 2-nm gold NPs in 6CHBT.

Recent Progress in Liquid-Crystal Optical Fibers and Their Applications in Photonics

The aim of this paper is to review and demonstrate a recent progress in liquid-crystal optical fibers and their applications in photonics. The review starts from early works with classical optical fibers modified with liquid crystals and ends up with the latest achievements in the field of photonic liquid crystal fibers (PLCFs). Potential applications and future perspectives of PLCFs are shortly summarized.

Electro-optical properties of photo-aligned photonic ferroelectric liquid crystal fibres

ABSTRACTElectro-optical and spectral studies of isotropic photonic crystal fibre (PCF) infiltrated with photo-aligned ferroelectric liquid crystal (FLC) under influence of external electric field are described. Desired alignment of FLC molecules is provided by generation of photo-aligning surface on the inner side of PCF structure. Propagation of light spectrum, as well as light attenuation have been investigated in details. Moreover, the electro-optical response times were measured and analysed.

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles.

Thermo- and electro-optical properties of a photonic liquid crystal fiber (PLCF) enhanced by the use of dopants have been investigated. A 6CHBT nematic liquid crystal was doped with four different concentrations of gold nanoparticles (NPs), 0.1, 0.3, 0.5 and 1.0 wt %, for direct comparison of the influence of the dopant on the properties of the PLCF. The thermo-optical effects of the liquid crystal doped with gold NPs were compared in three setups, an LC cell, a microcapillary and within the PLCF, to determine if the observed responses to external factors are caused by the properties of the infiltration material or due to the setup configuration. The results obtained indicated that with increasing NP doping a significant reduction of the rise time under an external electric field occurs with a simultaneous decrease in the nematic–isotropic phase transition temperature, thus improving the thermo- and electro-optical properties of the PLCF.

Nanoparticles-enhanced photonic liquid crystal fibers

Optical properties of photonic crystal fibers (PCFs) as well as micro-capillaries infiltrated with a 6CHBT liquid crystal (LC) doped with spherical silver (Ag) nanoparticles (NPs) have been studied. Three different concentrations of Ag NPs dopants were taken into consideration and their presence in the 6CHBT LC was found to modify the spectral properties of the infiltrated PCF. A significant improvement of switching times was observed for the NPs-doped LC-infiltrated PCF. Moreover, the Ag NPs-doped 6CHBT LC inside both micro-capillaries and PCFs was found to reduce the nematic-isotropic phase transition temperature.

All-fibre one-way filter based on both-end-filled photonic liquid crystal fibres

ABSTRACTWe propose an all-fibre one-way filter based on photonic crystal fibres (PCFs) with both ends of the air holes filled with liquid crystals. According to the resonant condition of the antiresonant reflecting optical wave-guide (ARROW) model, the transmission characteristics of the proposed photonic liquid crystal fibres (PLCFs) are directional. The transmission spectra can be tuned by changing the incident direction of the input light and the length of the empty PCF section. The shorter the length of the PLCFs, the more peaks in the transmission spectra. The all-fibre both-end-filled PLCFs can be applied to the design of one-way multiband filters.

Photonic bandgaps in selectively filled photonic crystal fibers

Simulations of selectively filled photonic crystal fibers using finite elements method were performed. Different patterns of filling were modeled and compared to an empty and fully filled fiber. Dependence of effective refractive indices of guided modes, phase birefringence and confinement losses on guided wavelength was investigated. A comparison of width of photonic bandgaps in different structures was made. Full Text: PDF ReferencesPh. St. J. Russell, "Photonic-Crystal Fibers", J. Lightwave Technol. 24, 4729 (2006) CrossRef Y. Han, S. Tan, M. K. K. Oo, D. Pristinski, S. Sukhishvili, and H. Du, "Towards Full-Length Accumulative Surface-Enhanced Raman Scattering-Active Photonic Crystal Fibers", Adv. Mat. 22, 2647 (2010) CrossRef S. Ertman, A. H. Rodríguez, M. M. Tefelska, M. S. Chychłowski, D. Pysz, R. Buczyński, E. Nowinowski-Kruszelnicki, R. Dąbrowski, and T. R. Woliński, "Index Guiding Photonic Liquid Crystal Fibers for Practical Applications", J. Lightwave Technol. 30, 1208 (2012) CrossRef K. Mileńko, S. Ertman, T. R. Woliński, "Numerical Analysis of the Phase Birefringence of the Photonic Crystal Fibers Selectively Filled with Liquid Crystal", Mol. Cryst. Liq. Cryst. 596, 4 (2014) CrossRef Y. Wang, C. Liao, X. Zhong, Z. Li, Y. Liu, J. Zhou, and K. Yang, "Selective-fluid-filled photonic crystal fibers and applications", Proc. SPIE 8914, 89140J-1 (2013) CrossRef F. Wang, W. Yuan, O. Hansen, and O. Bang, "Selective filling of photonic crystal fibers using focused ion beam milled microchannels", Opt. Express 19, 17585 (2011) CrossRef T. Martynkien, G. Statkiewicz-Barabach, J. Olszewski et al., "Highly birefringent microstructured fibers with enhanced sensitivity to hydrostatic pressure", Opt. Express 18, 15113 (2010) CrossRef B. T. Kuhlmey, R.C. McPhedran, C. M. de Sterke, "Modal cutoff in microstructured optical fibers", Opt. Lett. 27, 1684 (2002) CrossRef

Low-birefringence liquid crystal mixtures for photonic liquid crystal fibres application

ABSTRACTSeries of low-birefringence liquid crystal mixtures composed of alkyl alkylbicyclohexyl carbonates and modified mixtures with other compounds have been formulated, their refractive indices and electric permittivity measured upon temperature. They exhibit the ordinary refraction index no lower than the refractive index of silica glass in a different range of temperature. This enables to observe in photonic liquid crystal fibres (PLCFs) a change in the light propagation mechanism from photonic band gap guiding to modified total internal reflection at different temperatures. Selected applications of PLCFs are also discussed.

Influence of the core size on light propagation in photonic liquid crystal fibers

In this paper analyses of mode distribution, confinement and experimental losses of the photonic crystal fibers with different core sizes infiltrated with liquid crystal are presented. Four types of fibers are compared: with single-, seven-, nineteen- and thirty seven solid rods forming the core in the same hexagonal lattice of seven “rings” of unit cells (rods or capillaries). The experimental results confirming the influence of the core diameter on light propagation are also included. The diameter of cores determines not only the number of modes in the photonic liquid crystal fiber but also is correlated with experimentally observed attenuation. For fibers with larger cores confinement losses are expected to be higher, but the measured attenuation is smaller because the impact of liquid crystal material losses and scattering is smaller.

Light propagation in a photonic crystal fiber infiltrated with mesogenic azobenzene dyes

In this paper, light propagation in an isotropic photonic crystal fiber as well in a silica-glass microcapillary infiltrated with a mesogenic azobenzene dye has been investigated. It appeared that light spectrum guided inside the photonic crystal fiber infiltrated with the investigated azobenzene dye depends on the illuminating wavelength of the absorption band and on linear polarization. Also, alignment of the mesogenic azobenzene dye molecules inside silica glass microcapillaries and photonic crystal fibers has been investigated. Results obtained may lead to a new design of optically tunable photonic devices. Full Text: PDF ReferencesP. Russell. St. J. "Photonic-Crystal Fibers", J. Lightwave Technol. 24, 4729 (2006). CrossRef T. Larsen, A. Bjarklev, D. Hermann, J. Broeng, "Optical devices based on liquid crystal photonic bandgap fibres", Opt. Exp. 11, 2589 (2003). CrossRef D. C. Zografopoulos, A. Asquini, E. E. Kriezis, A. d'Alessandro, R. Beccherelli, "Guided-wave liquid-crystal photonics", Lab Chip, 12, 3598 (2012). CrossRef F. Du, Y-Q. Lu, S-T. Wu, "Electrically tunable liquid-crystal photonic crystal fiber", Appl. Phys. Lett 85, 2181 (2004) CrossRef D. C. Zografopoulos, E. E. Kriezis, "Tunable Polarization Properties of Hybrid-Guiding Liquid-Crystal Photonic Crystal Fibers", J. Lightwave Technol. 27 (6), 773 (2009) CrossRef S. Ertman, M. Tefelska, M. Chychłowski, A. Rodriquez, D. Pysz, R. Buczyński, E. Nowinowski-Kruszelnicki, R. Dąbrowski, T. R. Woliński. "Index Guiding Photonic Liquid Crystal Fibers for Practical Applications", J. Lightwave Technol. 30, 1208 (2012). CrossRef D. Noordegraaf, L. Scolari, J. Laegsgaard, L. Rindorf, T. T. Alkeskjold, "Electrically and mechanically induced long period gratings in liquid crystal photonic bandgap fibers", Opt. Expr. 15, 7901 (2007) CrossRef M. M. Tefelska, M. S. Chychlowski, T. R. Wolinski, R. Dabrowski, W. Rejmer, E. Nowinowski-Kruszelnicki, P. Mergo, "Photonic Band Gap Fibers with Novel Chiral Nematic and Low-Birefringence Nematic Liquid Crystals", Mol. Cryst. Liq. Cryst. 558(1), 184 (2012). CrossRef S. Mathews, Y. Semenova, G. Farrell, "Electronic tunability of ferroelectric liquid crystal infiltrated photonic crystal fibre", Electronics Letters, 45(12), 617 (2009). CrossRef V. Chigrinov, H-S Kwok, H. Takada, H. Takatsu, "Photo-aligning by azo-dyes: Physics and applications", Liquid Crystals Today, 14:4, 1-15, (2005) CrossRef A. Siarkowska, M. Jóźwik, S. Ertman, T.R. Woliński, V.G. Chigrinov, "Photo-alignment of liquid crystals in micro capillaries with point-by-point irradiation", Opto-Electon. Rev. 22, 178 (2014); CrossRef D. Budaszewski, A. K. Srivastava, A. M. W. Tam, T. R. Woliński, V. G. Chigrinov, H-S. Kwok, "Photo-aligned ferroelectric liquid crystals in microchannels", Opt. Lett. 39, 16 (2014) CrossRef J-H Liou, T-H. Chang, T. Lin, Ch-P. Yu, "Reversible photo-induced long-period fiber gratings in photonic liquid crystal fibers", Opt. Expr. 19, (7), 6756, (2011) CrossRef T. T. Alkeskjold, J. Laegsgaard, A. Bjarklev, D. S. Hermann, J. Broeng, J. Li, S-T. Wu, "All-optical modulation in dye-doped nematic liquid crystal photonic bandgap fibers", Opt. Exp, 12 (24), 5857 (2004) CrossRef K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, K. Aoki, "Reversible change in alignment mode of nematic liquid crystals regulated photochemically by command surfaces modified with an azobenzene monolayer", Langmuir, 4, 1214 (1988) CrossRef http://www.beamco.com/Azobenzene-liquid-crystals DirectLink K. A. Rutkowska, K. Orzechowski, M. Sierakowski, "Wedge-cell technique as a simple and effective method for chromatic dispersion determination of liquid crystals", Phot. Lett, Poland, 8(2), 51 (2016). CrossRef L. Deng, H.-K. Liu, "Nonlinear optical limiting of the azo dye methyl-red doped nematic liquid crystalline films", Opt. Eng. 42, 2936-2941 (2003). CrossRef J. Si, J. Qiu, J. Guo, M. Wang, K. Hirao, "Photoinduced birefringence of azodye-doped materials by a femtosecond laser", Appl. Opt., 42, 7170-7173 (2008). CrossRef

Multi-functional optical sensor based on plasmonic photonic liquid crystal fibers

A novel design of compact surface plasmon resonance multifunctional biosensor based on liquid crystal (LC) photonic crystal fiber (PCF) is proposed and studied. The suggested sensor has a central hole filled with LC as a temperature dependent material. Further, another large hole filled with liquid analyte has a gold nanorod as a plasmonic material. Therefore, the proposed senor can be used for temperature and analyte refractive index sensing via the coupling between the core guided modes in the LC core and the surface plasmon modes around the nano gold rod. The effects of the structure geometrical parameters are studied to maximize the sensitivity of the LC PCF biosensor. The numerical analysis is carried out using full-vectorial finite element method with perfectly matched layer boundary conditions. The reported multifunctional sensor offers high sensitivity of 5 nm/°C and 3700 nm/RIU (refractive index unit) for temperature and analyte refractive index sensing, respectively. To the best of the authors’ knowledge, it is the first time to introduce PCF biosensor with high sensitivity for temperature and analyte refractive index sensing as well.

Seven-core photonic liquid crystal fibers for simultaneous mode shaping and temperature sensing

Through doping liquid crystals into the core region, we propose a kind of seven-core photonic crystal fiber (PCF) which can achieve mode shaping and temperature sensing simultaneously in the communication window of 1.1–1.7 μm. To the best of our knowledge, this is the first time that the function of seven-core PCFs as temperature sensors is investigated. By using the full vectorial finite element method, the characteristics of the fiber with the temperature, such as the effective mode area, the waveguide dispersion, and the confinement loss, are analyzed. This kind of PCF can be competitive in providing temperature sensing in multi-core PCF lasers.

Double telecom band thermo-optic switch based on dual-line filled photonic liquid crystal fibres

ABSTRACTWe demonstrate a thermo-optic switch based on photonic liquid crystal fibres (PLCFs) in which two lines of air hole are selective filled with liquid crystal (LC), with a high extinction ratio of more than 20 dB around 1310 nm and 1550 nm. Only in the range of 2.0°C it can perform a turn off and on operation of transmitted light in the second telecom band around 1550 nm while the first telecom bands around 1310 nm is still on. Due to the splitting of the bandgap, the switching function is achieved in this kind of PLCFs. Before the cleaning point (CP) of LC, a broad bandgap from about 1120 nm to 1320 nm splits into two ones, which are continuing inducing huge bandgap extension to shorter wavelength and longer wavelength after the CP of LC, respectively. Moreover, the temperature responses around the CP of LC is also investigated. Its sensitivity is about −92.32 nm/°C around the CP of LC. Therefore, such kind of selective-filled PLCFs could find potential applications as thermo-optic switch and temperature sensor in the telecom band.

Tunable Optofluidic Polymer Photonic Liquid Crystal Fibers

New trends are presented in optofluidics based on microstructured photonic crystal fibers filled with liquid crystals. It significantly enhanced optical properties of the fibers and introduced new levels of tunability to photonic crystal fibers. The paper discusses basic research directions in fiber-based optofluidics and, in particular, in polycarbonate-based photonic liquid crystal fibers. Experimental and theoretical results are presented on polymer crystal fibers filled with nematic liquid crystal with two different types of dielectric anisotropies.

Electric Field Sensing With Photonic Liquid Crystal Fibers Based on Micro-Electrodes Systems

The paper describes four different types of micro-electrodes systems for dynamic electric field sensing with photonic crystal fibers infiltrated with liquid crystals. The shortest switching time ∼20 ms was achieved by using a flexible-flat-cable electrode system. A capillary system with four micro-electrodes (τ ∼ 36 ms) appeared to be the most convenient to operate with photonic liquid crystal fibers. The capillary system was also theoretically analyzed and presented in this paper.

Transmission characteristics of photonic crystal fibers based on filling different kinds of liquid crystals

The transmission characteristics of full-filled photonic liquid crystal fibers (PLCFs) which are filled with five kinds of liquid crystals (LCs) are experimentally studied and theoretically analyzed. The influences of temperature and external electric field on the transmission characteristics of PLCFs are also discussed in this paper. The transmission spectra of PLCFs show obvious bandgaps, and the number and the central wavelengths of the bandgaps depend on the average value of the refractive indices of LCs. By changing the temperature from 20 ℃ to 80 ℃, a blue shift in the bandgap is observed, and the maximum tuning range of the bandgap is 41 nm. Then, with the voltage turning from 0 V to 250 V, the output power of the transmission spectrum decreases, while the central wavelength of the bandgap is almost unchanged. Finally, the transmission spectrum keeps a good stability, even if the polarization state of the input light changes.