Temperature and vector bending sensing with a supermode fiber Bragg grating

PAPER • OPEN ACCESS Tempe a u e and ec o bending sensing wi h a supe mode ibe B agg g a ing To ci e his a icle: J Villa o o e al 2026 J. Phys. Pho onics 8 015015 View he a icle online o upda es and enhancemen s. You may also like Co ela ing he iscoelas ici y o b eas cance cells wi h hei malignancy Yasaman Nema bakhsh, Kuin Tian Pang and Chwee Teck Lim - Tempe a u e and mixing e ec s on elec ical esis i i y o ca bon ibe enhanced conc e e Ch is iana Chang, Gangbing Song, Di Gao e al. - Swi chable dual-wa eleng h Ho-doped ibe lase using hin co e ibe il e ope a ing a he ex ended 2 m wa eleng h egion Ha i h Ahmad, Khalil Kama uzzaman and Muhamad Zha i Samion - This con en was downloaded om IP add ess 82.130.128.46 on 27/11/2025 a 11:27 J. Phys. Pho onics 8(2026) 015015 h ps://doi.o g/10.1088/2515-7647/ae2170 Jou nal o Physics: Pho onics OPEN ACCESS RECEIVED 29 July 2025 REVISED 6 No embe 2025 ACCEPTED FOR PUBLICATION 19 No embe 2025 PUBLISHED 27 No embe 2025 O iginal con en om his wo k may be used unde he e ms o he C ea i e Commons A ibu ion 4.0 licence. Any u he dis ibu ion o his wo k mus main ain a ibu ion o he au ho (s) and he i le o he wo k, jou nal ci a ion and DOI. PAPER Tempe a u e and ec o bending sensing wi h a supe mode ibe B agg g a ing J Villa o o1,2,∗, M Alonso-Mu ias3, D Maldonado-Hu ado4, A Zo noza5, F Lindne 6, J Bie lich6, S Sales4and K Wond aczek6 1Depa amen o de Ingenie ía de Comunicaciones, Uni e si y o he Basque Coun y UPV/EHU, 48013 Bilbao, Spain 2IKERBASQUE, Basque Founda ion o Science, 48011 Bilbao, Spain 3Cen o de In es igaciones en ´ Op ica A. C., Loma del Bosque 115, Lomas del Campes e, León 37150 Guanajua o, Mexico 4Pho onics Resea ch Labs, iTEAM Resea ch Ins i u e, Uni e si a Poli ècnica de València, Camino de Ve a s/n, 46022 Valencia, Spain 5Depa men o Applied Ma hema ics, Uni e si y o he Basque Coun y UPV/EHU, 48013 Bilbao, Spain 6Leibniz Ins i u e o Pho onic Technology (Leibniz IPHT), 07745 Jena, Ge many ∗Au ho o whom any co espondence should be add essed. E-mail: agus injoel. il[email p o ec ed]us Keywo ds: coupled-co e ibe , mul ico e ibe s, ibe B agg g a ings, op ical ibe senso s, supe mode in e e ence, bending senso s, empe a u e senso s Abs ac Due o hei mul iple ad an ages, single-mode ibe B agg g a ings (FBGs) a e widely used in a my iad o p ac ical sensing applica ions. Howe e , hei concu en sensi i i y o s ain and em- pe a u e makes a e e ence senso necessa y in se e al si ua ions. He e, we demons a e ha a single supe mode FBG can be used o measu e bending and empe a u e. A specially designed wo coupled-co e op ical ibe (TCCF) ha suppo s wo supe modes was ab ica ed in which g a - ings we e insc ibed wi h em osecond o ul a iole lase s. The in e oga ion o he g a ings was ca ied ou wi h a con en ional FBG senso in e oga o . I was ound ha he e lec ion spec- um o he supe mode g a ing depended on i s insc ip ion in he TCCF. So, i was possible o ab ica e samples in which he e lec ion spec a exhibi ed wo na ow peaks e y close o each o he wi h well-de ined B agg wa eleng hs and e lec i i ies. C oss sensi i i ies and pola iza ion e ec s on he de ices we e s udied. I was ound ha wo B agg wa eleng hs and wo e lec i i - ies p o ided abundan da a o measu e bending o he TCCF, empe a u e, and o disc imina e in which di ec ion he TCCF was ben . Thus, we belie e ha he esul s epo ed he e can pa e he way o nex -gene a ion g a ing-based special y op ical ibe de ices ha a e capable o mul i- pa ame e sensing. The esul s and app oaches p oposed he e can also expand he use o B agg g a ing echnology. 1. In oduc ion Senso s based on single-mode ibe B agg g a ings (FBGs) ha e dis inc i e ad an ages which include eli- abili y, absolu e (wa eleng h encoded) measu emen s, immuni y o elec omagne ic in e e ence, and mul iplexing capabili y, among o he s [1–4]. Such senso s a e comme cially a ailable and widely used in a my iad o p ac ical applica ions. An impo an disad an age o con en ional single-mode FBG senso s is hei concu en sensi i i y o empe a u e and s ain. Thus, in se e al si ua ions a e e ence senso (an auxilia y B agg g a ing) o a mechanism o compensa e o empe a u e o he e ec o en i onmen al dis u bances, may be neces- sa y. Howe e , addi ional senso s o empe a u e compensa ion mechanisms may be imp ac ical in se - e al applica ions whe e he e a e limi a ions in space, size, o weigh . To ci cum en he issues men ioned abo e, he op ical ibe senso communi y has long been s i ing o achie e mul ipa ame e sensing wi h a single de ice. Ideally, such a de ice mus be able o p o ide simul aneous in o ma ion abou a a ge pa ame e , independen ly o along wi h o he en i onmen al pa ame e s, mainly empe a u e. To his end, di e en complex sensing a chi ec u es o combina ions o © 2025 The Au ho (s). Published by IOP Publishing L d J. Phys. Pho onics 8(2026) 015015 J Villa o o e al di e en pla o ms ha e been p oposed, see o example [5–7]. The disad an age o such mul ipa ame e sensing pla o ms is hei elabo a e ab ica ion p ocess, which may comp omise senso ep oducibili y and eliabili y. An al e na i e o achie e mul ipa ame e sensing is by means o B agg g a ings insc ibed wi h a il angle in single-mode ibe s (SMFs) [8–10]. Howe e , he in e oga ion o il ed g a ings is complex and expensi e as i en ails pola iza ion con olle s and high spec al esolu ion o e a b oadband, a leas 60 nm [11–13]. I is he e o e complica ed o in e oga e mo e han one il ed g a ing i hey a e placed in se ies. B agg g a ings insc ibed in bi e ingen (pola iza ion main aining) op ical ibe s can be used o sim- ul aneously moni o s ain and empe a u e as demons a ed in [14]. Ano he op ion o de ising mul- ipa ame e senso s is o insc ibe g a ings in mul imode ibe (MMF) s uc u es. MMF B agg g a ings ha e been s udied heo e ically and expe imen ally o mo e han wo decades, see o example [15, 16]. The e lec ion o MMF B agg g a ings ea u es se e al b oad e lec ion peaks ha can be se e al nanome e s apa . Such peaks can be acked and co ela ed wi h mo e han one pa ame e [17,18]. Ne e heless, he di icul y in con olling he numbe and ype o modes ha can be exci ed in a MMF, along wi h he ins abili y o he g a ing due o mode bea ing complica es he analysis o MMF B agg g a ings. He ein, we epo on he insc ip ion o B agg g a ings in an op ical ibe comp ising wo iden ical pho osensi i e co es sepa a ed by app oxima ely 14 µm. The wo coupled co e ibe (TCCF) was designed o allow op ical coupling be ween he co es. I was obse ed ha depending on he insc ip- ion o he g a ing, i s e lec ion spec um exhibi ed wo na ow peaks whose wa eleng h posi ion and e lec i i y could be co ela ed wi h empe a u e and bending. The e ec o pola iza ion and c oss sens- i i i ies on he de ices we e s udied. I was ound ha wi h a single supe mode FBG, i was possible o moni o TCCF bends in e ms o bo h bending di ec ion and bending angle as well as empe a u e. The main ad an age is ha he in e oga ion o ou mul ipa ame e sensing de ice can be ca ied ou wi h a comme cial FBG ead ou uni . Thus, he senso s based on supe mode FBGs p oposed he e can be used in se e al p ac ical applica ions. 2. Resul s and discussion 2.1. Design and ab ica ion o he wo coupled-co e ibe The TCCF consis s o wo ul a iole (UV) sensi i e co es embedded in a silica ma ix, whe e he o - cen e -co e is loca ed a 14 µm om he cen al co e. Each co e o he TCCF had a nume ical ape u e like ha o a con en ional SMF, which is 0.14 a 1550 nm. Pho osensi i i y was ob ained using GeO2in silica. The UV sensi i e GeO2-doped silica co es we e ab ica ed using he modi ied chemical apo deposi ion me hod. In o al, 26 GeO2-doped silica lay- e s we e deposi ed inside a F300 silica ube o ou e diame e o 22 mm, yielding a consolida ed GeO2- doped co e wi h a co e- o-clad diame e a io (CCDR) o 2.4; i.e. 5 mm co e and 12 mm p e o m dia- me e . The ob ained p e o m was hen g ound and polished o achie e a CCDR o 1.6. The g ound p e- o m was hen elonga ed o 1 mm ods. Two ods we e hen s acked oge he wi h 1 mm-diame e silica ods as schema ically depic ed in igu e 1(a) and inse ed in o a silica cladding ube (F300) o inal ibe p e o m. By using he so-called s ack-and-d aw me hod [19], he doped co es we e loca ed a he a ge posi ion in he inal TCCF, igu e 1(b). A sample o he ab ica ed TCCF was e ched o obse e he shape o he co es; such a sample was inspec ed wi h a scanning elec on mic oscope (SEM). In igu e 1(c), i can be obse ed ha he co es a e no pe ec ly ci cula . In he igu e, he mul i-laye s uc u e o he GeO2-doped co es is isible. The cladding o he ibe was made o pu e silica and had a diame e o 125 µm, his means, he same diame e and ma e ial o a con en ional SMF. The TCCF shown in igu e 1(b) suppo s only wo supe modes. The p o ile o one o hem is shown in igu e 2(a). The e ec on he supe mode in ensi y p o ile when he TCCF was subjec ed o a cu a u e o 1 ×10−5m−1is shown in igu e 2(b). The esul s shown in he igu e we e calcula ed a 1550 nm wi h comme cial simula ion so wa e (MODE om Lume ical). F om igu e 2(b), i can be no iced ha he in ensi y in he co es o he TCCF depends on he di ec ion o cu a u e. 2.2. Insc ip ion o B agg g a ings in he TCCF The insc ip ion o B agg g a ings in he TCCF was ca ied ou by means o wo well-es ablished ech- niques. The i s echnique in ol ed a em osecond ( s) lase equipped wi h a equency-doubled Yb- based lase ha emi s a 515 nm and ope a es a a pulse a e o 1 kHz. This lase was ocused h ough an oil imme sion objec i e (Plan-Apoch oma 63x/1.4 Oil M27) o c ea e pe iodic a ia ions in he 2 J. Phys. Pho onics 8(2026) 015015 J Villa o o e al Figu e 1. (a) Pho og aph o hexagonal s ack o he p e o m wi h silica ods (whi e ods) and he wo pho osensi i e ods (high- ligh ed in ed). (b) Mic oscopic image o a ab ica ed polyme -coa ed coupled-co e ibe . (c) SEM image o c oss sec ion o e ched TCCF end o isualizing he GeO2-doped co es. (d) Ske ch o an SMF-TCCF +FBG s uc u e ha was subjec ed o bending angles (θ) in he +xand −xdi ec ions. Lis he leng h o he segmen ha was ben . Figu e 2. (a) P o ile o a supe mode suppo ed by he TCCF. (b) E ec o cu a u e o 1 ×10−5m−1on he supe mode p o ile. All calcula ions we e done a 1550 nm wi h comme cially a ailable simula ions so wa e. e ac i e index wi hin he co e o he TCCF. This p ocess was achie ed using a poin -by-poin insc ip- ion echnique as epo ed in [20,21]. The second echnique in ol ed a UV lase wi h a wa eleng h o 193 nm and a phase mask [22,23]. Be o e he insc ip ion o he g a ings, app oxima ely 4 cm o TCCF we e usion spliced o a lead-in and lead-ou segmen s o SMF. The splicing o he SMF and he TCCF was by means o he clad alignmen me hod wi h a usion splice (model FSM-100P+ om Fujiku a). Thus, he cen al co e o he TCCF and he unique co e o he SMF we e axially aligned. Unde hese condi ions, he wo supe modes o he TCCF we e exci ed by he undamen al mode o he SMF. This exci a ion is qui e e icien as he nume ical ape u es o bo h wa eguides a e he same. The polyme coa ing o he TCCF was o ally emo ed wi h ace one. The B agg g a ings we e insc ibed app oxima ely in he middle o he TCCF segmen . Due o he lexibili y o he insc ip ion wi h s lase s, g a ings wi h di e en leng hs we e insc ibed in he TCCF. In addi ion, single g a ings we e insc ibed in he cen al o he o -cen e co e. Figu es 3(a) and (b) summa ize ou esul s. I can be no iced om hese igu es ha he e lec ion spec um o a sho s g a ing is b oade han ha o a long one. No e also ha when he g a ing is insc ibed only in he o -cen e co e, wo B agg wa eleng hs appea . Ano he collec ion o g a ings, all wi h he same leng h, we e insc ibed in he TCCF wi h UV lase and he phase mask echnique. Figu es 3(c) and (d) display he e lec ion spec a o six samples. We obse ed e lec ion pa e ns wi h wo B agg wa eleng hs, sepa a ed app oxima ely 190 pm, in 60% o he ab ica ed samples and one B agg wa eleng h in he es o samples. This can be a ibu ed o he exposu e o he wo pho osensi i e co es o he UV lase pa e n. Thus, o ensu e e lec ion spec a wi h wo B agg wa eleng hs i is impo an ha he wo pho osensi i e co es a e equally exposed o he UV lase pa e n. This can be achie ed by o ien ing he TCCF be o e he g a ings a e insc ibed. Howe e , as he ab ica ion o B agg g a ings can be moni o ed in eal ime, samples ha do no ha e wo B agg wa eleng hs can be disca ded o dual pa ame e sensing applica ions o he easons discussed in he ollowing sec ions. 2.3. Bending and empe a u e sensing A simple se up was implemen ed o ca y ou he bending expe imen s. The TCCF wi h B agg g a - ing was clea ed wi h an angle o a oid F esnel e lec ion. The SMF-TCCF+FBG s uc u e was hen placed in can ile e posi ion, see igu e 1(d). To secu e he s uc u e we used a high p ecision ibe o a o (HFR007, om Tho labs). The dis ance om he poin whe e he s uc u e was immobilized o 3 J. Phys. Pho onics 8(2026) 015015 J Villa o o e al Figu e 3. Spec a o B agg g a ings insc ibed in he TCCF wi h a em osecond lase in he cen al co e (a) and o -cen e co e (b). The g a ing leng hs a e indica ed. (c) and (d) Spec a o samples o 6 mm-long g a ings insc ibed in he TCCF wi h a UV lase and phase mask. he poin whe e i was ben , Lin igu e 1(d), was 15.30 ±0.01 mm. The bending angle o he SMF- TCCF +FBG segmen was a ied by displacing i in s eps o 100 ±1 mic ome e s in he +xand −x di ec ions, acco ding o he coo dina e sys em shown in igu e 1(d). The e lec ion spec um a each bending angle was moni o ed wi h a comme cial FBG in e og- a o (Hype ion Si155 om LUNA Inno a ions) connec ed o a lap op. An ad hoc LabVIEW p og am was implemen ed o moni o he B agg wa eleng hs (λB) and hei e lec i i ies. The FBG in e oga o and lap op we e con igu ed in a local a ea ne wo k ia TCP-IP p o ocol o communica e wi h each o he . The e lec ion spec um o he SMF-TCCF +FBG s uc u e was displayed in linea scale. The B agg wa eleng hs posi ions and hei e lec i i ies we e ound by applying he Peak De ec o VI om LabVIEW. Figu es 4(a) and (b) display, espec i ely, he e lec ion spec a obse ed when he TCCF was ben a di e en angles in he +xand −xdi ec ions. No e ha he posi ions o λB1 and λB2 do no change when he TCCF is ben ; see he e ical do ed lines in igu es 4(a) and (b). Howe e , he e lec i i y o he wo peaks changes in opposi e manne . Figu e 4(a) shows ha R1( e lec i i y o peak loca ed a λB1) inc eases wi h he bending angle bu R2( e lec i i y o peak loca ed a λB2) dec eases. I he di ec ion o bending changes, R1dec eases and R2inc eases, see igu e 4(b). This means ha he TCCF bending angle and di ec ion can be co ela ed wi h R1and R2, which a e simple o moni o . To compensa e o possible luc ua ions o he ligh sou ce, we co ela ed he bending angle wi h he a io o R2/R1. The ini ial o ien a ion o he TCCF co es wi h espec o he bending di ec- ion was a bi a y. This ini ial posi ion was conside ed o be 0◦. F om his posi ion, he TCCF was hen o a ed 30◦, 60◦, and 90◦and was ben in +xand −xdi ec ions wi h he p ocedu e desc ibed abo e. In all cases, we collec ed he e lec ion spec a and measu ed R2and R1. The calib a ion cu es ha we e ob ained o di e en o ien a ions o he TCCF co es wi h espec o he di ec ion o he bending a e displayed in igu e 5. We obse ed ha a la ge angles, he beha io o he senso was nonlinea . F om igu e 5 he bending sensi i i ies we e calcula ed. The maximum sensi i i ies in he +xand −x di ec ions we e ound o be, espec i ely, 0.23 and −0.279 a.u. pe deg ee. These sensi i i ies a e ∼500% highe han hose published in [24]. F om he igu e, i can be no ed ha independen ly o he TCCF co e o ien a ion wi h espec o he di ec ion o bending, om he a io R2/R1i is possible o quan i y he bending deg ee and o know i he TCCF was ben o he +xo o he −xdi ec ion. No e ha in p e ious wo k [24], his was no possible. In addi ion, in [24], ligh luc ua ions could no be com- pensa ed o as e lec i i y changes o a single peak we e moni o ed. Mo eo e , in ou case, he posi ions o λB1 and λB2 can be used o moni o empe a u e wi h high accu acy. Thus, sensing o empe a u e and di ec ional bending is easible wi h a single supe mode g a ing. To in es iga e he e ec o empe a u e on he supe mode B agg g a ing, he SMF-TCCF+FBG s uc- u e was placed in a empe a u e calib a o (Fluke model 9103). No e ha o eal-wo ld bending meas- u emen s, he TCCF mus be coa ed, p o ec ed o packaged. So, he analyzed empe a u e ange was om −20 ◦C o +90 ◦C, which co e s a wide ange o en i onmen s and he empe a u e ope a ing ange o polyme ic coa ings o op ical ibe s. The obse ed spec a and calib a ion cu e a e shown in 4 J. Phys. Pho onics 8(2026) 015015 J Villa o o e al Figu e 4. Expe imen al e lec ion spec a obse ed when he TCCF ibe was ben di e en angles in he +xdi ec ion (a) and he −xdi ec ion (b). In bo h g aphs, λB1,λB2,R1, and R2deno e, espec i ely, B agg wa eleng hs and e lec i i y o he peaks. Figu e 5. Calib a ion cu es obse ed when he co es o he TCCF we e placed a di e en o ien a ions wi h espec o he x- di ec ion ( he di ec ion o bending). The ini ial o ien a ion o he TCCF co es was deno ed as 0◦. igu e 6. I can be no ed om he igu e ha he posi ions o he wo B agg wa eleng hs changed lin- ea ly wi h empe a u e. The empe a u e sensi i i y, calcula ed wi h ei he o he wo B agg wa eleng hs, was ound o be 9.9 pm ◦C−1. The a io R2/R1as a unc ion o empe a u e is also shown in he bo om inse g aph o igu e 6. I was obse ed ha he alue R2/R1changed app oxima ely ±1.3% in he measu ed empe a u e ange. This alue is much lowe han hose obse ed when he TCCF was ben , which anges om 50% o 75%. Thus, empe a u e-independen bending o dual pa ame e senso s can be de eloped wi h he s uc u e epo ed he e. In ei he case, he senso in e oga ion can be ca ied ou wi h widely a ailable comme cial ins umen s. 5 J. Phys. Pho onics 8(2026) 015015 J Villa o o e al Figu e 6. B agg wa eleng hs as a unc ion o empe a u e. The op inse g aph shows he obse ed spec a a di e en empe a - u es, and he bo om inse g aph shows he R2/R1 a io e sus empe a u e. Figu e 7. Re lec ion spec a o a supe mode B agg g a ing a 40 di e en s a es o pola iza ion (SOP) o he inpu ligh . The inse g aph shows he no malized R2/R1 a io obse ed a he 40 SOP. Guide modes, and supe modes in pa icula , a e, in gene al, sensi i e o pola iza ion, so, he pe - o mance o a sensing de ice based supe modes may be a ec ed by changes o pola iza ion. Thus, he e ec o pola iza ion on he e lec ion spec a o he supe mode g a ings and on R2,R1,λB1 and λB2 was in es iga ed. To do so, an elec onic ibe pola iza ion con olle (model PC-15-1-1-2, om Phoenix Pho onics) ha ope a es om 1300 o 1640 nm was used in he expe imen s. The con olle allowed us o launch any s a e o pola iza ion (SOP) o he supe mode B agg g a ing. Ou indings a e launching 40 di e en SOP o he de ice a e shown in igu e 7. No e ha al hough he wo maxima and he min- imum (dip) be ween hem change, he R2/R1 a io a ies less han 2%, see he inse g aph o igu e 7. The changes o λB1 and λB2 ha we e obse ed we e less han 6 pm. The e o e, we can conclude ha he supe mode B agg g a ing p oposed he e can ope a e wi h any SOP o he inpu ligh . The ope a ion mechanism o supe mode B agg g a ings has been discussed in di e en publica ions, see o example [24–27]. The condi ion o B agg e lec ion indica es ha speci ic wa eleng hs a e e lec- ed and ha he in ensi y o he B agg wa eleng hs depends on he coupling coe icien o he o wa d and backwa d p opaga ing supe modes. In gene al, wo B agg wa eleng hs (λB1 and λB2) can be expec- ed. Howe e , ou expe imen al esul s sugges ha i depends on he insc ip ion o he B agg g a ing in he TCCF. P e ious wo ks ha e demons a ed ha coupled-co e ibe s a e highly sensi i e o bending [24,28]. The la e induces s ess o he ibe co es and al e s hei e ac i e indices [29]. Consequen ly, he ield in ensi ies o he supe modes a e modi ied, hus leading o ene gy ans e be ween hem. Howe e , bending has no e ec on he B agg wa eleng hs. Fo hese easons, a single supe mode B agg g a ing can be used o moni o wo pa ame e s: bending and empe a u e wi h minimal o negligible c oss sensi i i y. 6 J. Phys. Pho onics 8(2026) 015015 J Villa o o e al 3. Conclusions In his wo k, we ha e epo ed on he ab ica ion o an op ical ibe comp ising wo iden ical pho o- sensi i e co es sepa a ed app oxima ely 14 mic ome e s and he insc ip ion o B agg g a ing in one o in bo h co es. I was demons a ed ha a single supe mode FBG ha has he po en ial o moni o bending angle and di ec ion as well as empe a u e. The in e ac ion o he g a ings wi h wo supe modes suppo ed by he wo coupled-co e ibe makes he e lec ion spec um ha e wo well-de ined peaks ha a e close o each o he . I was obse ed ha bending o he TCCF changed only he e lec i i y o he wo peaks and empe a u e al e ed only he B agg wa eleng hs. The e ec o pola iza ion on he e lec ion spec a o he g a ings was s udied. Ou esul s sugges ha pola iza ion has no signi ican e ec on he pe o mance o ou senso . In e es ingly, he wo B agg wa eleng hs and he wo alues o e lec i i y p o ide abundan da a o measu e empe - a u e and bending deg ee o he TCCF as well as o disc imina e in which di ec ion he TCCF was ben . These ea u es we e obse ed a di e en o ien a ions o he co es wi h espec o he di ec ion o bend- ing. The e o e, he posi ion o he TCCF is no ele an . As he e lec ion o supe mode B agg g a ings has wo na ow peaks ha a e sepa a ed less han 200 pm, hei mul iplexing is s aigh o wa d. Any comme cially a ailable FBG ead ou uni can be used o in e oga e he g a ings. The e o e, he supe mode FBGs epo ed he e can be a ac i e in applica- ions whe e i is impo an o moni o bending deg ee and empe a u e and o disc imina e he di ec- ion o bending o he op ical ibe wi h a single compac de ice. Da a a ailabili y s a emen The da a ha suppo he indings o his s udy a e a ailable upon easonable eques om he au ho s. Acknowledgmen s This wo k was unded in pa h ough P ojec s PDC2022-133885-I00; PID2023-152763NB-I00; INNOFIBER PID2023-152314OB-I00, and SMARTMOORING Ce p-2022-00382, PCI2023-145987-2 unded by he Spanish MCIU/AEI /10.13039/501100011033 and he Eu opean Union Nex Gene a ion EU/PRTR, IT11452-22 unded by he Basque Go e nmen and P2022-06 unded by he EU Ho izon2020 Ac phas 4R GA 825051. I is also pa ially suppo ed by he Cá ed a Chip Fo ónico UPV TSI-069100- 2023-0002, and PROMETEO 2021/015 Resea ch Excellency Awa d unded by he Gene ali a Valenciana. M. Alonso-Mu ias acknowledges he suppo ecei ed om SECIHTI h ough he Na ional Pos doc o al S ays P og am (G an No. 787628). The au ho s acknowledge Sh abya Shukla o he assis ance in some expe imen s. Au ho con ibu ions J Villa o o 0000-0002-0842-9173 Concep ualiza ion (equal), Fo mal analysis (equal), In es iga ion (equal), Supe ision (equal), W i ing – e iew & edi ing (equal) M Alonso-Mu ias 0000-0002-5161-9562 Da a cu a ion (equal), Fo mal analysis (equal), So wa e (equal) D Maldonado-Hu ado In es iga ion (equal), Me hodology (equal) A Zo noza 0000-0003-2127-6789 Da a cu a ion (equal), Fo mal analysis (equal), Me hodology (equal), So wa e (equal) F Lindne In es iga ion (equal), Me hodology (equal), Resou ces (equal) J Bie lich Fo mal analysis (equal), In es iga ion (equal), Me hodology (equal) S Sales Funding acquisi ion (equal), In es iga ion (equal), Resou ces (equal) K Wond aczek 0000-0002-6268-9136 Funding acquisi ion (equal), P ojec adminis a ion (equal), Resou ces (equal), Supe ision (equal) 7 J. Phys. Pho onics 8(2026) 015015 J Villa o o e al Re e ences [1] Hill K O and Mel z G 1997 Fibe B agg g a ing echnology undamen als and o e iew J. Ligh wa e Technol. 15 1263–76 [2] Saho a J K, Gup a N and Dhawan D 2020 Fibe B agg g a ing senso s o moni o ing o physical pa ame e s: a comp ehensi e e iew Op . Eng. 59 1 [3] Zhang F, Hao Y, Tian A, Yang Z, Zhang B, Fukuda T and Shi C 2025 Wea able ibe B agg g a ing senso s o physiological signal and body mo ion moni o ing: a e iew IEEE T ans. Ins um. Meas. 74 1–24 [4] Kashyap R 2010 Fibe B agg G a ings (Academic) [5] Pe ec S and Donlagi´ c D 2019 Mul ipa ame e ibe -op ic senso s: a e iew Op . Eng. 58 1 [6] Zhao Y, Zhao H, L R-Q and Zhao J 2019 Re iew o op ical ibe Mach–Zehnde in e e ome e s wi h mic o-ca i y ab ica ed by em osecond lase and sensing applica ions Op . Lase s Eng. 117 7–20 [7] Liu T, Jiang J, Liu K, Wang S, Zhang X, Hu H, Ding Z, Guo H, Li Y and Zhang W 2021 Re iew o ibe mechanical and he mal mul i-pa ame e measu emen echnologies and ins umen a ion J. Ligh wa e Technol. 39 3724–39 [8] Wong A C L, Chung W H, Tam H-Y and Lu C 2011 Single il ed B agg e lec o ibe lase o simul aneous sensing o e ac i e index and empe a u e Op . Exp ess 19 409 [9] Yuezhen S, Zhijun Y, Kaiming Z, Binbin L, Biqiang J, Chengbo M, Qizhen S and Lin Z 2021 Excessi ely il ed ibe g a ing senso s J. Ligh wa e Technol. 39 3761–70 [10] Guo T, Liu F, Guan B-O and Albe J 2016 Til ed ibe g a ing mechanical and biochemical senso s Op . Lase Technol. 78 19–33 [11] Bu o O V, Tomyshe K A, Nechepu enko I A, Do o eenko A V and Niki o S A 2022 Til ed ibe B agg g a ings and hei sensing applica ions Phys.-Usp. 65 1290–302 [12] Cauche eu C, Villa o o J, Liu F, Loyez M, Guo T and Albe J 2022 Mode-di ision and spa ial-di ision op ical ibe senso s Ad . Op . Pho on. 14 1 [13] Jean-Ruel H and Albe J 2024 Recen ad ances and cu en ends in op ical ibe biosenso s based on il ed ibe B agg g a ings T AC T ends Anal. Chem. 174 117663 [14] Ma uck L C, Cab i a P D, Pin o J L, Ma ques C A and Nascimen o M S 2023 Cus omized op ical ibe bi e ingen senso s o mul- ipoin and simul aneous empe a u e and adial s ain acking o li hium-ion ba e ies Ad . Sens. Res. 22200046 [15] Mizunami T, Djambo a T V, Niiho T and Gup a S 2000 B agg g a ings in mul imode and ew-mode op ical ibe s J. Ligh wa e Technol. 18 230–5 [16] Kuhne J F, Rocha A M, De Oli ei a V, Kalinowski H J and Kamikawachi R C 2018 Expe imen al and nume ical s udy on e ac i e index senso s based on ib e B agg g a ings insc ibed in mul imode ib e Meas. Sci. Technol. 29 025102 [17] Lim J, Yang Q, Jones B E and Jackson P R 2002 S ain and empe a u e senso s using mul imode op ical ibe b agg g a ings and co ela ion signal p ocessing IEEE T ans. Ins um. Meas. 51 622–7 [18] Yang T, Qiao X, Rong Q and Bao W 2017 Fibe B agg g a ings insc ip ions in mul imode ibe using 800 nm em osecond lase o high- empe a u e s ain measu emen Op . Lase Technol. 93 138–42 [19] Schus e K, Unge S, Aichele C, Lindne F, G imm S, Li zkendo D, Kobelke J, Bie lich J, Wond aczek K and Ba el H 2014 Ma e ial and echnology ends in ibe op ics Ad . Op . Technol. 3447–68 [20] Sanipa in B, Sánchez L A, A qués L and Sales S 2024 Mic osphe e-Augmen ed PDMS in eg a ion in ape ed FBG small-scale senso s o enhanced empe a u e sensi i i y Sci. Rep. 14 1–11 [21] Li H e al 2023 Fibe oscilla o o 5 kW using ibe B agg g a ings insc ibed by a isible em osecond lase Chin. Op . Le . 21 021404 [22] Hill K O, Malo B, Bilodeau F, Johnson D C and Albe J 1993 B agg g a ings ab ica ed in monomode pho osensi i e op ical ibe by UV exposu e h ough a phase mask Appl. Phys. Le . 62 1035–7 [23] O honos A 1997 Fibe B agg g a ings Re . Sci. Ins um. 68 4309–41 [24] Flo es-B a o J A, Mad igal J, Zubia J, Sales S and Villa o o J 2022 Coupled-co e ibe B agg g a ings o low-cos sensing Sci. Rep. 12 1280 [25] Wu Z, Zhang H, Shum P P, Shao X, Huang T, Seow Y M, Liu Y, Wei H and Wang Z 2015 Supe mode B agg g a ing combined Mach-Zehnde in e e ome e o empe a u e-s ain disc imina ion Op . Exp ess 23 33001 [26] Liu Z, Zheng D, Mad igal J, Villa o o J, An onio-Lopez J E, Schülzgen A, Amezcua-Co ea R, Zou X, Pan W and Sales S 2021 Tempe a u e-insensi i e cu a u e senso based on B agg g a ings w i en in s ongly coupled mul ico e ibe Op . Le . 46 3933 [27] Dong X, Xie Y-H, Ou J-L, Wu C, Li J and Guan B-O 2023 Supe mode B agg g a ing insc ibed in a s ongly coupled se en-co e ibe and i s esponses o empe a u e and cu a u e Op . Exp ess 31 3258 [28] Villa o o J, Van Newki k A, An onio-Lopez E, Zubia J, Schülzgen A and Amezcua-Co ea R 2016 Ul asensi i e ec o bending senso based on mul ico e op ical ibe Op . Le . 41 832 [29] Mu akami Y and Sudo S 1981 Coupling cha ac e is ics measu emen s be ween cu ed wa eguides using a wo-co e ibe couple Appl. Op . 20 417 8