Index Guiding Photonic Liquid Crystal Fibers for Practical Applications

1208 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 30, NO. 8, APRIL 15, 2012

Index Guiding Photonic Liquid Crystal Fibers forPractical Applications

Sławomir Ertman, Aura Higuera Rodríguez, Marzena M. Tefelska, Miłosz S. Chychłowski,Dariusz Pysz, Ryszard Buczyński, Edward Nowinowski-Kruszelnicki, Roman Dąbrowski, and

Tomasz R. Woliński, Member, IEEE

(Invited Paper)

Abstract—Photonic liquid crystal fibers (PLCFs) can be catego-rized in two principal groups: index guiding PLCFs and photonicbandgap PLCFs. In this paper we focus on index guiding PLCFsin which effective refractive index of the micro structured claddingfilled with liquid crystal is lower than refractive index of the fibercore. In these fibers broadband propagation of light is observedand also effective tuning of guiding properties is possible. In thispaper PLCFs with tunable attenuation, retardation and polariza-tion dependent losses are reported.We also enumerate some poten-tial applications of index-guiding PLCFs, together with discussionof few technical issues important in the context of future develop-ment (i.e., effective electrical steering and connecting with stan-dard fibers).

Index Terms—Birefringence, liquid crystals, photonic crystalfibers, tunable fiber optics devices.

I. INTRODUCTION

T RANSMISSION properties of photonic crystal fibers(PCFs) can be tailored in a wide range by changing

the geometry of their microstructured cladding [1]. Dynamictuning can be obtained after infiltration of the fiber microholeswith substances those optical properties could be easily mod-ified by external factors. Liquid crystals (LCs) belong to themost interesting materials for such applications due to the highsensitivities to external physical fields. Photonic liquid crystalfibers (PLCFs) combine unique properties of both photoniccrystal fibers and liquid crystals.Generally, in a PLCF light can be guided by two different

mechanisms: index-guiding (similar to the classical waveguide

Manuscript received June 30, 2011; revised August 25, 2011; acceptedSeptember 15, 2011. Date of publication October 17, 2011; date of currentversion March 16, 2012. This work was supported in part by the Polish Ministryof Science and Education under the grant N517 554139 and partially by the“Mistrz“ and “Start” Programmes of the Foundation for Polish Science.S. Ertman is with Warsaw University of Technology, Faculty of Physics,

Koszykowa 75, 00-662 Warsaw, Poland (e-mail: [email protected]).A. H. Rodríguez, M. M. Tefelska, M. S. Chychłowski, and T. R. Woliński

are also with Warsaw University of Technology, Faculty of Physics,Warsaw 00-662, Poland (e-mail: ahiguerar@gmail; [email protected];[email protected]; [email protected]).D. Pysz is with Institute of Electronics Materials Technology, Wolczynska

133, 01-919 Warsaw, Poland (e-mail: [email protected]).R. Buczynski is with Institute of Geophysics, University of Warsaw, Pasteura

7, 00-681 Warsaw, Poland (e-mail: [email protected]).E. Nowinowski-Kruszelnicki and R. Dąbrowski are with Military Uni-

versity of Technology, Kaliskiego 2, 00-908 Warsaw, Poland (e-mail:[email protected]; [email protected]).Digital Object Identifier 10.1109/JLT.2011.2172393

effect based on the total internal reflection) and the photonicbandgap (PBG) effect. The PBG propagation occurs when theeffective refractive index of the microstructured cladding ishigher than the refractive index of the core, and in this case onlyselected wavelengths can be guided. So far most researchershave been using PCFs made of silica glass, those refractiveindex 1.46 is lower than both refractive indexes of majorityof liquid crystals and so only PBG propagation was possible.There have been a number of papers presenting thermal tuningof the PBGs (i.e., [2]–[5]), later on also electric tuning of thePBGs was obtained (i.e., [6], [7]). There have been also numberof works with more sophisticated tuning of the PBGs in thePLCFs, i.e., all-optical tuning in a PCF filled with a LC dopedeither with dyes [8] or with azobenzene [9], and frequency tun-ability of the PCF filled either with dual frequency [10], [11] ornanoparticle-doped liquid crystals [12]. It is worth to mentionthat together with PBGs tuning also an effective control ofpolarization properties was demonstrated [i.e., [13], [14]].In this paper we focus on index-guiding PLCFs, those

guiding properties and tuning possibilities significantly differfrom the PBG-guiding PLCFs. We demonstrate that effectivetuning of attenuation, retardation and polarization dependentlosses is possible in such fibers. Potential applications ofindex-guiding PLCFs are also briefly discussed.

II. ADVANTAGES OF INDEX GUIDING PLCFS

Index guiding in PLCFs was observed for the first time in2006 [7], when thermal tuning of the guiding mechanism wasobtained by using a special LCmixture with the ordinary refrac-tive index lower (in a certain temperature range) than the refrac-tive index of the silica glass. Later on low-loss index-guidingpropagation was obtained in the PLCF based on the PCF madeof the high-index glass [15], [16]. The main advantage of theindex-guiding PLCFs is broadband propagation with signifi-cantly lower scattering losses due to the limited penetration ofthe LC filled holes. In case of bandgap guidingmode field deeplypenetrates the PCF microstructured cladding (Fig. 1(ab)), sosuch propagation is strongly depending on the “quality” of thephotonic crystal formed in the cladding, i.e., any fluctuations inthe holes diameters can significantly increase the losses. In caseof liquid crystal filled holes there is also an issue of increasedscattering caused by the liquid crystal—even if molecules arewell oriented with special techniques (i.e., [17]), there are still

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ERTMAN et al.: INDEX GUIDING PHOTONIC LIQUID CRYSTAL FIBERS 1209

Fig. 1. Examples of the modes profiles guided in the PLCFs by the photonicbandgap phenomenon (a, b) and index-guided mode (c).

Fig. 2. Two types of the host PCFs discussed in this paper: (a) IEMT PCF-18made of Schott F2 glass—refractive. index 1.62; (b) IEMT PCF-14 made ofPBG08 glass [17]—refractive index 1.95 (hole diameters are 5 m, 5.2 mand distances between holes are 8.2 m, 7.6 m respectively).

thermal fluctuations of molecular alignment, which have a sim-ilar impact on attenuation as fluctuations in the diameters of themicro-holes. In contrary, index-guided mode is well localizedin the core (Fig. 1(c)), and thus it is much less sensitive on bothfluctuations in the geometry and scattering by the LCmolecules.Moreover, the mode profile can be similar to the mode of thestandard single mode fibers and as a result light coupling to theindex-guiding PLCF is more effective.In this paper we will present some examples of tunable index

guiding PLCFs, which include tunable attenuation, retardationand tunable polarization dependent losses. We will also discusssome perspectives of potential application of such fibers, in-cluding also optical fiber sensing.

III. MATERIALS AND SETUPS

Most liquid crystals have refractive indexes (both ordinaryand extraordinary) higher than index of silica glass, thusindex-guiding in silica glass based PLCFs is possible only inspecial case, if specially designed LC mixtures are used [7],allowing for example for thermal tuning of the attenuation[18]. However a choice of the LC mixtures is very limited, andin most cases to achieve index-guiding it is necessary to heatthe sample [18]. In this work we decided to use specially de-signed PCFs made of multi-component glasses: commerciallyavailable Schott F2 glass [19] and prototype high-index glassPBG-08 (14.06% SiO2, 39.17% PbO, 27.26% Bi2O3, 14.26%Ga2O3, 5.26% CdO) [20]. The Schott F2 glass refractive indexis about 1.62, and index of the PBG-08 glass is about 1.95. Bothfibers used in this work have been manufactured by the Insti-tute of Electronics Materials Technology (Warsaw, Poland).Scanning electron microscopy photographs and diameters ofPCF14 and PCF18 fibers are given on Fig. 2. PCFs were filledwith LCs by the capillary action and similarly to our previousworks a planar alignment of the LC molecules was observedwith polarizing microscope [i.e., [7], [14]].

Fig. 3. Refractive indexes of Schott F2 and PBG-08 glasses compared to therefractive index of silica glass and refractive indexes of liquid crystals used inexperiments presented in this paper.

Due to the fact, that host PCF refractive indexes are relativelyhigh (when compared to silica glass), there is a broad rangeof LC mixtures allowing for index-guiding. In this paper wedecided to use three types of LCs synthesized at the MilitaryUniversity of Technology (Warsaw, Poland): 1658A, 1679 and1850. Ordinary refractive index of all three LCs was almost thesame 1.52 , but value of the extraordinary index (and thusbirefringence) was different (Fig. 3). It worth to mention, thatextraordinary index of 1850 LC was almost equal to the indexof the Schott F2 glass, which allowed us to build effectivelytunable polarizer (described in Section VI of this paper).In our measurements as a light source we used Tunics Plus

laser (tunable in the range of 1500–1640 nm). Polarization oflight was controlled by polarizer and manual polarization con-troller. The PLCFs samples was placed between two flat elec-trodes and distance between electrodes was equal to the diam-eter of the host fiber ( 125 m). In all experiments PLCFs weretuned with square wave 1 kHz signal supplied from high voltageamplifier. From both sides PLCFs were connected to the stan-dard single-mode pigtails. The output signal was analyzed withPAT 9000B polarimeter, which allowed for measurement of op-tical power and visualization of the changes in the state of po-larization (Fig. 4).

IV. DYNAMICALLY TUNABLE ATTENUATION

As a first example of index-guiding PLCF we will present afiber in which electric tuning of attenuation was possible. It wasbased on the PCF-18, made Schott F2 glass, those refractiveindex was about 1.62. The holes of the fiber were filled withLC mixture 1658) those ordinary and extraordinary refractiveindexes were 1.54 and 1.93 respectively. After infiltration LCmolecules were oriented parallel to the fiber axis, so the effec-tive refractive index of the cladding was lower than index of thecore and thus low loss index guiding was observed. Transverseelectric field was applied to the sample to change the orienta-tion of the LC molecules. It was expected that one polarizationwill be still index guided since other should be attenuated orguided by the PBG mechanism with much higher attenuation.However strong coupling between modes was observed (prob-ably due to the fact that extraordinary index was much higherthan index of the glass) and both polarizations were attenuated

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Fig. 4. Experimental setup used in measurements.

Fig. 5. Electrically tunable attenuation in the PLCF (host PCF refractive index:1.618, guest LC refractive indices: 1.54 and 1.93).

in the same way. In this experiment PLCF was glued to the twopieces of SMF-28 fiber and without electric field attenuation ofthe sample was about 5 dB. Normalized change of the attenu-ation measured at 1550 nm is shown in the Fig. 5—it could benoticed that almost linear increase of the losses was observedwith the increasing intensity of the steering electric field. It isworth to mention that this effect was reversible and repeatable,so these PLCF structures can be used to build electrically tun-able attenuators.It is also worth to mention, that tuning range can be relatively

easily increased by using longer pieces of the PLCFs. In ourexperiment we have used about 10 cm of PCF-18 filled with1658 LC. So if the PLCF section would be two times longer,it should be possible to tune the attenuation in the range higherthan 70 dB. However also insertion losses would be doubled inthat case, so in practical application length of the PLCF shouldcompromise those two factors.To explain the phenomena of tunable attenuation presented

above we can give only qualitative explanation based on nu-merical simulations performed for planar and transverse orien-tations. In case of planar orientation both polarizations are indexguided with low attenuation. When molecules are reoriented tothe transverse state, one polarization is still index guided, sincefor the orthogonal polarization only selective PBG propagationis possible (Fig. 6).Fig. 7 presents confinement losses of the guided modes. It

can be noticed that for both polarizations confinement lossesstrongly depend on the wavelength. The effect is quite obviousfor PBG-guided modes, but for index-guided modes sucha behavior can be slightly surprising suggesting that there

Fig. 6. Effective indexes and PBG mode profiles calculated with full-vectorfinite element method for IEMT-PCF18 fiber filled with 5CB with assumptionof the transverse alignment of the LC molecules—simultaneous polarizationdependent propagation of the PBG and index-guided modes.

Fig. 7. Confinement losses calculated for modes presented in Fig. 6.

is residual coupling between both polarizations. However itshould be pointed that the assumption of linearly polarizedmodes in PLCFs is only an approximation, since guided modesare in fact hybrid-modes and contain also other polarizationcomponents with much lower intensities, although high enoughto observe the polarization coupling.Tunable attenuator discussed in this sectionwas characterized

at 1550 nm. In comparison to the results of the numerical sim-ulations presented in Fig. 7 it can be noticed that for the trans-verse orientation (at 1550 nm) both polarizations are character-ized by very high confinement losses (for wavelengths higherthan 1500 nm it was not possible to find any core-modes), andfor the planar orientation the both polarizations are well guided.Fig. 7 can also suggest that the same PLCF can be used as

a polarizer, if the operating wavelength would be changed to

ERTMAN et al.: INDEX GUIDING PHOTONIC LIQUID CRYSTAL FIBERS 1211

Fig. 8. Phase retardation in the function of intensity of the steering electricfield.

1200–1300 nm, because of high difference between confine-ment losses of the PBG-guided modes and index-guided modes.However, in the practice it appeared that application of elec-tric field resulted in an increased attenuation also for index-guided polarization. Much better performance was obtained forthe PCF-18 filled with the 1850 LC mixture, which is describedin Section VI of this paper.

V. DYNAMICALLY TUNABLE RETARDATION

As a second example of the index guiding PLCF we willpresent a fiber, in which it was possible to tune retardation be-tween both orthogonal modes. This structure was based on thePCF made of PBG08 multi-component glass, those refractiveindex was relatively high 1.95 . The fiber was filled withthe 1679 LC and its length was 8 cm. In one of our previouspapers we have demonstrated that continuous and repeatabletuning of the phase birefringence is possible after filling thisfiber with LCs those both refractive indexes are lower than re-fractive index of the glass [16]. In the PLCFs based on the PCFsmade of the PBG08 glass it was also possible to obtain low-losspropagation for any orientation of the LC molecules, since ef-fective index of the cladding was always much lower than indexof the core.The heart of the retarder (or tunable waveplate) is a PLCF

made of the PBG08 glass placed between two flat electrodes,and leading in/out SMF-28 fibers are terminated with the FC/PCconnectors. Performance of the device is presented in Fig. 8.It was possible to obtain continuous, repeatable and reversibletuning of the retardation from 0 to 2 (see Fig. 9—one fullcircle on Poincare sphere corresponds to the 2 phase change).Results presented in Fig. 8 were obtained at the operating wave-length 1550 nm, and total losses of the device (including lossesat FC/PC connectors) were near to 10 dB and remain constantwhen the retardation was tuned. The device was steered withthe square wave at 1 kHz and was operating at room tempera-ture (due to the fact that LCs are highly sensitive to temperature,in practical application the device should be thermally stabi-lized or steering should automatically compensate temperaturechanges).

Fig. 9. Poincare sphere traces recorded for two different PLCFs described inthe paper showing electrically tunable retardation (a) and electrically tunablepolarization dependent losses (b).

VI. TUNABLE POLARIZATION DEPENDENT LOSSES

To obtain dynamically tunable polarization dependent loses(PDL) we decided to use the PCF-18 made of the F2 glass filledwith the 1850 LC mixture, because refractive index of F2 glassis almost equal to the extraordinary index of the 1850 LC. In thatcase in off-voltage case (when all molecules are parallel to thefiber axis) both polarizations are index guided with low losses(it was possible to obtain less than 5 dB insertion losses of thewhole setup, which include two glued connection to SM fibers).However, when LC molecules were reoriented perpendicularlyto the fiber axis, one polarization would be strongly attenuated(or more precisely would escape to the cladding), since orthog-onal modes would be still index guided with low losses.Initially, the effect of electric tuning for this sample was very

similar for those observed for the previous sample—circulartrace was observed on the Poincare sphere indicating change ofthe phase birefringence. However, when the intensity of elec-tric field applied to the sample was increased, the radius of thecircles become smaller, and finally the trace stopped at a pointof the Poincare sphere (Fig. 9(b)). Such a spiral trace on thePoincare sphere is a clear indicator that one polarization compo-nent is attenuated. At the beginning of tuning a phase change be-tween two polarization components lead to polarization changesfrom linear to circular. But if one of the polarization componentsbecomes attenuated, the phase change leads to a continuouschange of the state of polarization from linear to elliptical—it isno longer possible to obtain circular polarization, because onepolarization component is much smaller.To ensure that the we obtained tunable polarization dependent

losses we have coupled linearly polarized light to the PLCF atdifferent azimuths, which allowed us to identify two axes of thefiber. For first polarization we have noticed significant changesin the transmission, since for orthogonal there was only smallchanges, and at the end of tuning propagation was even betterthat on the beginning (Fig. 10).Attenuation characteristics for orthogonal polarizations

presented in Fig. 10 were normalized to the attenuation of thesample at the off-voltage state. It should be mentioned, that itwas possible to assembly the sample in which total insertionlosses were smaller than 5 dB (including losses at connectionsbetween PLCF and standard fiber), however during measure-ments the sample was sensitive for external factors (i.e., stress,bending) which in some cases resulted in increase of the in-sertion losses to more than 10 dB. However if the sample was

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Fig. 10. Attenuation of the two orthogonal modes of the PCF-18 filled with1850 LC in the function of effective electric field intensity. Slightly increasedattenuation of the 2-nd polarization at the beginning of the tuning may resultfrom increased scattering of light when reorientation of molecules starts.

Fig. 11. Polarization dependent losses of the PCF-18 filled with the 1850 LCin the function of effective electric field intensity.

mechanically stabilized, the insertion losses were kept on theconstant level.From Fig. 10 it is easy to obtain the characteristic for polar-

ization dependent losses in the function of electric field inten-sity, as a difference between attenuation of orthogonally polar-ized modes. We decided to plot this characteristic on a separategraph to clearly indicate, that it is possible to tune PDL in therange higher than 30 dB (Fig. 11). In most cases such a level ofPDL is acceptable for polarizers, so the PLCF can work effec-tively as an electrically tunable all-in-fiber polarizer.It can be noticed, that both Figs. 10 and 11 show some non-

monotonous changes of attenuation/PDL. An initial increase inattenuation of both modes at 0 V/ m can be explained by anincreased scattering induced by LC-filled holes at the beginningof the reorientation process (similar behavior was observed i.e.,in [14]). For higher intensities of electric fields scattering be-comes smaller, since LC molecules are gradually getting betteroriented on the transverse direction. Thus, for one polarizationattenuation becomes even smaller than at off-voltage state, how-ever for other polarization non-continuous behavior is observed.A possible explanation of these phenomena can be that for inthis case attenuation depends on two factors: variable scatteringby the LC and decreasing contrast between refractive indexes

Fig. 12. Different electrode configurations for electrical steering of PLCFs: (a)simple two electrode assembly; (b) four electrode setup and (c) setup with twoflat electrodes, and two cylindrical wires on the sides of the fiber. Setups (b) and(c) allows for dynamic change of the direction of the electric field.

of the core and cladding. Moreover, as we showed in our pre-vious theoretical work [21], reorientation of the LCmolecules isnot uniform in each hole and possibly it can also result in somenon-monotonous behavior. However, on the current level of ournumerical expertise we are not able to give exact explanation ofthese phenomena. We can be only sure that for planar orienta-tion (off-voltage state) both polarizations are well guided, sincefor perfectly transverse orientation only one polarization modeis possible.

VII. POTENTIAL APPLICATIONS

It seems that index-guiding PLCFs can find a broad range ofapplications. Fibers with tunable attenuation can be used as vari-able attenuators or even as low-frequency (few Hz) modulators.PLCFs with tunable phase birefringence can be used for man-ufacturing all-in-fiber tunable components, i.e., tunable wave-plates, or tunable phase shifters. PLCF based on the PCF-18filled with the 1850 LC can be used as effectively tunable polar-izers. These components can be further utilized for assemblingmore sophisticated devices such as all-in-fiber polarization con-trollers and polarization mode dispersion compensators.The PLCFs are highly sensitive for external physical fields,

so it seems that they could be also used as sensing parts invarious types of sensors, i.e., temperature, pressure or electricfield sensors [22]. However, high cross-sensitivity is usually avery important issue in these fibers, so in practice sensor headsbased on the PLCFs can find limited applications. From thepractical point of view the PLCFs can be much more useful

ERTMAN et al.: INDEX GUIDING PHOTONIC LIQUID CRYSTAL FIBERS 1213

in optical fiber sensing setups to act rather as tunable compo-nents than sensing elements. For example, PLCF-based tunablewaveplates and phase shifters can be very useful in some typesof the optical fiber sensing systems, i.e., in polarimetric sensors,in which these components can be used for dynamic adjusting ofpolarization of light coupled to the sensing fiber. Index-guidingPLCFs could be used in interferometric sensors based on theSagnac loops, where tunable phase shifters could be appliedfor dynamic control of the initial phase delay between orthog-onal modes guided in the loop. Tunable polarizers and polariza-tion controllers can be used in the optical sensing setups basedon highly birefringent fiber Bragg gratings—in this case dy-namic switching between orthogonal working polarizations canbe easily obtained.The functionality of the PLCFs could be even more extended

by using four-electrode steering (similar to those discussed in[13] and [23]). Four-electrode steering will allow for a dynamicchange in the field direction, and consequently it will be possibleto make fibers with continuously tunable birefringence (or PDL)by also with arbitrarily switchable birefringence axes. It will bealso possible to build tunable polarizer, in which polarizationaxis will be dynamically changed and will be dependent on thedirection of the electric field.One of the main issues in the context of practical applications

is connecting of the PLCF based on multi-component glasseswith standard SM fibers (splicing of the PBG08 glass with thesilica glass is a very challenging task since chemical composi-tions and melting temperatures of both glasses are totally dif-ferent). In our experiments we decided to use a photo-curableadhesive which refractive index was close to the index of silica,and it seems that for some applications such connections can beacceptable. To make such a connection, a small amount of theadhesive should be putted between both fibers, that were pre-cisely adjusted to optimize the coupling and finally the “splice”should be cured with the UV light. In our attempts we was ableto make connection with attenuation smaller than 1dB, howeverit was quite time consuming, so in the context of practical appli-cation such method of connection may be somehow expansive.An example of such the “cold-splice” is shown in Fig. 13(b),whereas in Fig. 13(a) an example of an electrically tunable de-vice based on index guiding PLCF is presented.

VIII. CONCLUSION

In this paper we have presented three types of index-guidingphotonic liquid crystal fibers, in which it was possible to effec-tively tune such guiding properties as attenuation, retardationand polarization dependent losses. We believe that such fiberscan be effectively used in many practical applications as tun-able attenuators, tunable waveplates and tunable fibers. To en-sure that such devices have stable and repeatable characteristicsa technique of LC molecule orientation and stabilization shouldbe applied in manufacturing process. The most promising tech-nique seems to be a photoalignment, which allows for non-con-tact patterned orientation of the LC molecules [24]. This tech-nique can also reduce losses of PLCFs [25] and extend func-tionality of devices, i.e., if the patterned orientation would becombined with four-electrode steering.

Fig. 13. Electrically tunable retarder based on the high index PCF filled withLC; (a) general overview of device; (b) close up to the “cold splice” made withphoto-curable adhesive [15].

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Sławomir Ertman received the M.S. degree in physics from the Warsaw Uni-versity of Technology (WUT), Warsaw, Poland, in 2005. His Master thesis wasFirst Prize at the National Contest for Best M.Sc. thesis in the field of opto-electronics in 2005. He received the Ph.D. degree in physics from the WUT on2009. His thesis concerned the polarization properties of photonic crystal fibersfilled with liquid crystal.He is currently with the Faculty of Physics, WUT. His main research interests

include photonic fibers infiltrated with liquid crystals, polarization properties ofoptical fibers and optical fiber sensors.

Aura Higuera Rodriguez is currently pursuing the M.S. degree at FriedrichSchiller University, Jena, Germany. She was awarded with an Erasmus Mundusscholarship in the program OpSciTech 2010–2012 (Master in optics science andtechnology), she spent her first year at Warsaw University of Technology inPoland, Warsaw.During that time she performed an internship in the Faculty of Physics at

WUT assembling a tunable Photonic Liquid Crystal Fiber polarizer and recentlystarted to venture in the optical industry performing an internship in Carl ZeissAG in the IMT department as a software developer for industrial optical mea-surement.

Marzena Tefelska received the M.Sc. degree and Engineer diploma in op-toelectronics from the Warsaw University of Technology, Warsaw, Poland, in2007, where she is currently working toward the Ph.D. degree with the facultyof physics.Her research interests include photonic crystal fibers filled with liquid crys-

tals, liquid crystals, and sensor fibers.Ms. Tefelska has been a member of the International Society for Optical En-

gineers (SPIE) since 2007. She has been a member of the Photonics Society ofPoland since 2008. She received the Third Prize at the Adam Smolinski Contestfor the best master thesis for 2006–2007 in the optoelectronics discipline and in2009 she got a scholarship of European Social Fund through the WUT Devel-opment Programme.