Recent developments on the manufacture of tellurite glass fibers are presented. Technical
issues related to glass synthesis, preform manufacturing and fiber drawing as well as prospective of
commercial exploitation are discussed

Boetti N.G.

Heidt A.

Honkanen S.

Lousteau J.

Milanese D.

Mura E.

Richardson D.J.

Rondinelli M.

English

LOUSTEAU, JORIS

MURA, EMANUELE

BOETTI, NADIA GIOVANNA

Richardson D. J.

MILANESE, DANIEL

Archivio istituzionale della Ricerca -  Università degli Studi di Parma

New Developments in Tellurite Glass Fibers

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

04 August 2020POLITECNICO DI TORINORepository ISTITUZIONALENew Developments in Tellurite Glass Fibers / Lousteau J.; Mura E.; Rondinelli M.; Boetti N.G.; Heidt A.; Richardson D.J.;Honkanen S.; Milanese D.. - ELETTRONICO. - (2013), pp. 1-2. ((Intervento presentato al convegno Workshop onSpecialty Optical Fibers tenutosi a Sigtuna, Sweden nel 28-30 August 2013.OriginalNew Developments in Tellurite Glass FibersPublisher:PublishedDOI:Terms of use:openAccessPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/2517721 since:Optical Society of America (OSA)W2.2.pdf Workshop on Specialty Optical Fibers and their Applications© OSA 2013New Developments in Tellurite Glass Fibers  Joris Lousteau1*, Emanuele Mura2, Marco Rondinelli2,  Nadia G. Boetti2, Alexander Heidt3,  David J. Richardson3, Seppo Honkanen4 and Daniel Milanese2  1 PhotonLab, Istituto Superiore Mario Boella, Via Pier Carlo Boggio, 61, 10138 Turin, Italy 2 PhotonLab, DISAT, Politecnico di Torino, 24, 10129 Turin, Italy 3 Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, Hampshire. SO17 1BJ, United Kingdom. 4 University of Eastern Finland, Department of Physics and Mathematics, Yliopistokatu 7, 80100 Joensuu, Finland *Corresponding authors: lousteau@ismb.it    Abstract: Recent developments on the manufacture of tellurite glass fibers are presented. Technical issues related to glass synthesis, preform manufacturing and fiber drawing  as well as prospective  of commercial exploitation are discussed. OCIS codes: 060.2390 Fiber optics, Infrared; 160.4530 Nonlinear optical materials; 170.2750 Glass and other amorphous materials.   1.  Tellurite glass fiber fabrication  Its outstanding physical properties make of silica the glass material of choice for optical fiber applications. However, in many cases the use of alternative oxide glass compositions, in particular for the development of more compact or/and more efficient devices, could be advantageous. Some phosphate glass and multicomponent silicate glass compositions have been used for the development of commercial fiber laser operating at 1.5 and 2 um respectively.  However, other promising oxide glass compositions such as germanate or tellurite glasses still remained to be truly exploited in the form of commercial  devices.   Tellurite glass allows for concentration in rare-earth ions doping up to 1021 ions/cm3, it also possesses a high nonlinear refractive index (50.10-16 cm2/W), a low phonon energy making mid-IR transmission possible up to 5 m and a Verdet constant of  30 rad·(T·m)-1 making this glass suitable for magneto-optic applications as well.  Like for most oxide glasses, although a controlled environment is required for the synthesis of tellurite glasses, the process is not technically challenging if compared to non-oxide soft glass preparation. The typical process is carried out by melting chemical precursors in noble metal crucible and quenching the liquid melt in suitable metal mold. The intrinsic optical losses of tellurite glass manufactured using this approach is lower than 0.1 dB/km which demonstrates the potential of this material for optical applications.     “Standard” techniques used for manufacturing step index tellurite glass optical fibre preform involve the assembly of discrete core rods and tube elements when using a direct rod-in-tube technique. In spite of the care taken during fiber manufacturing, the typical loss value in single-mode fiber reaches few dB/m. This value can be improved down to 0.1 dB/m using built-in-casting or suction casting techniques. Although the above loss values are still tolerable for short length device, the reproducibility of the manufacturing techniques in terms of preform geometry and fiber quality remains a limitation for  exploiting tellurite glass fiber at industrial level.  2. Towards generation of high power mid-IR Supercontinum (SC) spectrum in tellurite glass fibers  To date most research efforts have focused on rare-earth ions doped tellurite glass, leading to laboratory demonstration of fiber laser devices operating at 1.5 m and 2 m. For exploiting the nonlinear properties of tellurite glass, research groups have reported the generation of supercontinuum spectrum in holey optical fibers microstructured in order to tailor the zero dispersion wavelength (ZDW) of the fiber near the pumping wavelengths of 1 m and 1.5 m.  Actually, tellurite glass possess a ZDW in the 2 m region so that pumping at this wavelength releases the need of ZDW tailoring. Mid-IR SC spectrum can then be generated in standard step index fiber without any particular geometrical constrains expect for the fiber to operate in the single-mode regime.   Through this approach,  Kulkarni et al. [1] generated a 2.6 W supercontinuum spectrum spanning from 2 m to 4 W2.2.pdf Workshop on Specialty Optical Fibers and their Applications© OSA 2013m, using a 8.5 m long step index fibres made of low nonlinearity ZBLAN glass. The step index fiber design results in decreased complexity and improved control and repeatability in the fiber manufacturing process as compared to holey fibers (HFs). With a nonlinear refractive index nearly 20 times that of ZBLAN glass, a higher damage threshold and a higher thermo-mechanical and chemical compatibility with silica glass fibre devices, tellurite glass fibres offer thus the possibility to develop similar multiwatt supercontinuum sources in the mid-IR but in a compact device format   For this purpose we have developed a tellurite glass composition meeting the following requirements:  Low O-H radicals content for mid-IR transmittance as shown in Figure 1. Subsequent extrinsic losses due to O-H band absorption are of  the order of  50 dB/m.  High polarisability with a refractive index (n) at 1.533 m n = 2.067.  High glass transition temperature, Tg = 390 °C and extended glass stability with an onset crystallisation temperature of Tx = 550 °C.      Figure 1: FTIR transmission spectrum of tellurite glass developed for  high average power SC generation in mid-IR   Taking benefit of the recent progresses achieved to generate 2 m pulsed sources [2], the development of an optical fibre made from this tellurite glass composition should allow for producing high power and compact supercontinuum sources operating in the mid-IR.     3. References:  Ojas P. Kulkarni, Vinay V. Alexander, Malay Kumar, Michael J. Freeman, Mohammed N. Islam, Fred L. Terry, Jr., Manickam Neelakandan, and Allan Chan, “Supercontinuum generation from ~1.9 to 4.5 μm in ZBLAN fiber with high average power generation beyond 3.8 μm using a thulium-doped fiber amplifier”, JOSA B, Vol. 28, Issue 10, pp. 2486-2498 (2011).  A.M.Heidt, Z.Li, J.K.Sahu, P.C.Shardlow, M.Becker, M.Rothhardt, M.Ibsen, R.Phelan, B.Kelly, S.-U.Alam, D.J.Richardson. “100 kW peak power picosecond thulium-doped fiber amplifier system seeded by a gain-switched diode laser at 2 microns”. Optics Letters 2013 Vol.38(10) pp.1615-1617. 

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New Developments in Tellurite Glass Fibers

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Archivio istituzionale della Ricerca - Università degli Studi di Parma

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)