Ultra Large Amplification Bandwidth Of Er3+ And Tm3+ At S And L Band From Teo2-wo3-na2o-nb 2o5 Glass Doped Optical Fibers

Tellurite glasses optical fibers became promising for optical amplifiers due to its high rare earth ions solubility and very large amplification bandwidth. Among several tellurite glasses the TeO2-WO 3-Na2O-Nb2O5 system show one of the largest bandwidth. Our previous characterization of lifetime using the Ω2, Ω4, Ω6, Judd-Ofelt parameters indicate a quantum efficiency maximum for 7500ppm Er3+ concentration. Therefore we decided to produce jointed Er3+ and Tm3+ single mode optical fibers with this glass system keeping the 7500ppm Er3+ concentration and varying the Tm3+ concentration from 2500ppm to 15000ppm. This single mode fiber was pumped by 120mW of the semiconductor laser at 790nm and we observed a flat ASE bandwidth from 1400 to 1570nm for the 5000ppm Tm3+ concentration.5723243247Jeong, H., Oh, K., Han, S.R., Morse, T.F., Broadband amplified spontaneous emission from an Er3+-Tm 3+ - Codoped silica fibar (2003) Opt. Lett., 28, pp. 161-163Reisfeld, R., Jorgensen, C.K., (1987) Handbook on the Physics and Chemistry of Rare Earths, 9, pp. 1-90. , K. A. Gschneidner, Jr. and L. Eyring (Eds.), Elsevier ScienceChen, C.Y., Petrin, R.R., Yeh, D.C., Sibley, W.A., Concentration-dependent energy-transfer processes in Er3+-and Tm3+ -doped heavy-metal fluoride (1989) Opt. Lett., 14, pp. 432-434Miniscalco, W.J., Quimby, R.S., General procedure for the analysis of Er3+ cross sections (1991) Opt. Lett, 16, pp. 258-26

Carbon Nanotube Doped Tellurite Glasses

In the past it was observed that buck ball doped glasses showed enhanced optical nonlinearities. However, carbon nanotubes are much more stable than buck ball and should be a better choice for that purpose. Therefore we decided to investigate the possibility to produce carbon nanotubes doped tellurite glasses and measured their optical nonlinearities. Tellurite glasses already have a larger nonlinearity compared to silica, and other, glasses. We produced TeO 2-ZnO tellurite family glasses doped with multi wall Carbon Nanotube (CNT). The CNTs acquired from Carbolex were vigorously mechanically mixed with the tellurite glass precursors and melted in platinum crucible around 650°C in a controlled atmosphere inside an electrical induction furnace. We used the lowest temperature possible and controlled atmosphere to avoid the CNT oxidation. The glass melt was cast in a stainless steel and thermally treated at 300°C for 5 hours to relieve internal stresses. The samples were than cutted and polished to perform the optical characterization. We measured refractive index and thermo physical properties, such as vitreous transition Tg, crystallization onset Tx and melting Tf temperatures. Raman spectroscopy showed the possible presence of CNTs.6890Iijima, S., (1991) Nature, 354, p. 56http://www.ati.surrey.ac.uk/news/n, onlinearDiMaio, J., Rhyne, S., Yang, Z., Fu, K., Czerw, R., Xu, J., Webster, S., Ballato, J., (2003) Information Sciences, 149, p. 69Aoki, Y., Okubo, S., Kataura, H., Nagasawa, H., Achiba, Y., (2005) Chem. Lett, 34 (4), p. 562Misra, S.K., Watts, P.C.P., Valappil, S.P., Silva, S.R.P., Roy, I., Boccaccini, A.R., (2007) Nanotechnology, 18, p. 07570

Photothermal Spectroscopic Characterization In Teliurite Glasses Codoped With Rare-earth Ions

Thermal Lens (TL) and spectroscopic characterizations were performed in 70TeO2-19WO3-7Na2O-4Nb2O 5 (mol%) tellurite glasses. TL measurements were accomplished in Er3+/Tm3+ co-doped tellurite glasses in function of the Tm2O3 concentration (0.4 -1.6 ×1020 ions/cm3). Fluorescence spectra at 488 nm showed that Er 3+/Tm3+co-doped tellurite glasses present several emission bands between (500-1800) nm. However, the more iniense emission bands correspond to the Er3+ and Tm3+ transitions ( 4I13/2 → 4I15/2 and 3F4 → 3H6), respectively. The absolute nonradiative quantum efficiency (φ) was determined by TL method. Higher values of φ were obtained with the increase of Tm2O 3 concentration inside of the Er3+/Tm3+ co-doped tellurite glasses. These results are corroborated by the Judd-Ofelt calculations.6116Ryba-Romanowski, W., Effect of Temperature and activator concentration on luminescence decay of erbium-doped tellurite glass (1990) J. Lumin., 46, pp. 163-172Tanabe, S., Hirao, K., Soga, N., Upconversion fluorescences of TeO2 and Ga2O 3. based oxide glasses containing Er3+ (1990) J. Non-cryst. Solids, 122, pp. 79-82Inoue, S., Nukui, A., Yamamoto, K., Yano, T., Shibata, S., Yamane, M., Refractive index patterning of tellurite glass surfaces by ultra short pulse laser spot heating (2002) J. Mater. Sci., 37, pp. 3459-3465Huang, L., Jha, A., Shen, S., Chung, W.J., Visible emissions at 592 and 613 nm in Er3+-Eu3+ -codoped tellurite fibers (2004) Opt. Commun., 239, pp. 403-408Chillece, E.F., Rodriguez, E., Neves, A.A.R., Moreira, W.C., César, C.L., Barbosa, L.C., Er3+-Tm3+ co-doped tellurite fibers for broadband optical fiber amplifier around 1550 nm band (2005) Opt. Fiber Tech.Tanabe, S., Suzuki, K., Soga, N., Hanada, T., Mechanisms and concentration dependence of Tm3+ blue and Er3+ green up-con version in codoped glasses by red-laser pumping (1995) J. Lumin., 65, pp. 247-255Dai, S.X., Yang, J.H., Liu, Z.P., Wen, L., Hu, L.L., Jiang, Z.H., The luminescence of Er3+, Yb3+, Tm 3+-codoped tellurite glass pumped at 970 nm (2003) Acta Physica Sinica, 52, pp. 729-735Shen, S.X., Jha, A., Huang, L.H., Joshi, P., 980-nm diode-pumped Tm3+/Yb3+-codoped tellurite fiber for S-band amplification (2005) Optics Letters, 30, pp. 1437-1439Shen, X., Nie, Q., Xu, T., Peng, T., Gao, Y., Green and red upconversion emission and energy-transfer between Er 3+ and Tm3+ions in tellurite glasses (2004) Phys. Lett. A, 332, pp. 101-106Daf, S., Yang, J., Xu, S., Dai, N., Hu, L., Jiang, Z., The spectroscopic properties of Er3+, Yb3+, Tm 3+ -codoped tellurite glass (2003) Proc. SPIE, 4990, pp. 150-156. , Rare-Earth-Doped Materials and Devices Vil, S. Jiang, J. Lucas (Eds.)Lima, S.M., Sampaio, J.A., Catuncla, T., Bento, A.C., Miranda, L.C.M., Baesso, M.L., Mode-mismatched thermal lens spcctrometry for thermo-optical properties measurement in optical glasses: A review (2000) J. Non-cryst. Solids, 273, pp. 215-227Sampaio, J.A., Catunda, T., Gama, S., Baesso, M.L., Thermo-optical properties of OH-free erbium-doped low silica calcium aluminosilicate glasses measured by thermal lens technique (2001) J. Non-cryst. Solids, 284, pp. 210-216Lima, S.M., De Camargo, A.S.S., Nunes, L.A.O., Catunda, T., Fluorescence quantum efficiency measurements of excitation and nonradiative deexcitation processes of rare earth 4f-states in chalcogenide glasses (2002) Appl. Phys. Lett., 81, pp. 589-591Oliveira, S.L., Lima, S.M., Catunda, T., Nunes, L.A.O., Rohling, J.H., Bento, A.C., Baesso, M.L., High fluorescence quantum efficiency of 1.8 μm emission in Tm-dopcd low silica calcium aluminate glass determined by thermal lens spectroscopy (2004) Appl. Phys. Lett., 84, pp. 359-361Jacinto, C., Oliveira, S.L., Nunes, L.A.O., Catunda, T., Bell, M.J.V., Thermal lens study of the OH influence on the fluorescence efficiency of Yb3+ -doped phosphate glasses (2005) Appl. Phys. Lett., 86Sampaio, J.A., Gama, S., Baesso, M.L., Catunda, T., Fluorescence quantum efficiency of Er3+ in low silica calcium aluminate glasses determined by mode-mismatched thermal lens spectromctry (2005) J. Non-cryst. Solids, 351, pp. 1594-1602Pilla, V., Lima, S.M., Catunda, T., Medina, A., Baesso, M.L., Jenssen, H.P., Cassanho, A., Thermal quenching of the fluorescence quantum efficiency in colquiriite crystals measured by thermal lens spcctrometry (2004) J. Opt. Soc. Am. B., 21, pp. 1784-1791Pilla, V., Catunda, T., Balogh, D.T., Faria, R.M., Zilio, S.C., Thermal lensing in Polyvinyl alcoholVpolyaniline blends (2002) J. Polym. Sc., Part B Polym. Physics, 40, pp. 1949-1956Lima, S.M., Catunda, T., Lebullenger, R., Hernandes, A.C., Baesso, M.L., Bento, A.C., Miranda, L.C.M., Temperature dependence of thermo-optical properties of fluoride glasses determined by thermal lens spectrometry (1999) Phys. Rev. B, 60, pp. 15173-15178Lima, S.M., Sampaio, J.A., Catunda, T., De Camargo, A.S.S., Nunes, L.A.O., Baesso, M.L., Hewak, D.W., Spectroscopy, thermal and optical properties of Nd3+ -doped chalcogenide glasses (2001) J. Non-cryst. Solids, 284, pp. 274-281Zou, X., Izumitani, T., Spectroscopic properties and mechanisms of excited state absorption and energy transfer upconversion for Er3+ -doped glasses (1993) J. Non-cryst. Solids, 162, pp. 68-8

Micro-size Tapered Silica Fibers For Sensing Applications

In this work we show results of controlled tapered fibers using a Vytran instrument. The tapered silica fibers were produced by pulling a 50μm length by heating time. The minimum taper diameter was around 3μm and the maximum taper length was around 600μm. The evanescent field effect, in the near infra red (NIR) region, was observed to the tapers with diameter inferior to 15μm. These micro-size tapers no modify the waveguide dispersion spectra. This device could be used to splice a conventional fiber to photonic crystal fibers and also as liquid and gas sensors In this work is reported a fiber optic sensor in the form of taper using the concept of the evanescent field. We show the sensor sensitivity using different liquid materials. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).8120The Society of Photo-Optical Instrumentation Engineers (SPIE)Foster, M.A., Gaeta, A.L., Ultra-low threshold supercontinuum generation in sub-wavelength waveguides (2004) Opt. Express, 12 (14), pp. 3137-3143Jung, Y., Brambilla, G., Richardson, D.J., Broadband single-mode operation of standard optical fibers by using a sub-wavelength optical wire filter (2008) Opt. Express, 16 (19), pp. 14661-14667Tong, L., Gattass, R.R., Ashcom, J.B., He, S., Lou, J., Shen, M., Maxwell, I., Mazur, E., Subwavelength-diamter silica wires for low-loss optical wave guiding (2003) Nature, 426, pp. 816-819Zhang, L., Gu, F., Lou, J., Yin, X., Tong, L., Fast detection of humidity with a subwavelengthdiameter fiber taper coated with gelatin film (2008) Opt. Express, 16 (17), pp. 13349-13353Espinola, R.L., Dadap, J.I., Osgood Jr., R.M., McNab, S.J., Vlasov, Y.A., C-band wavelength conversion in silicon photonic wire waveguides (2005) Opt. Express, 13 (11), pp. 4341-4349Lizé, Y.K., Mägi, E.C., Ta'Eed, V.G., Bolger, J.A., Steinvurzel, P., Eggleton, B.J., Microstructured optical fiber photonic wires with subwavelength core diameter (2004) Opt. Express, 12 (14), pp. 3209-3217Foster, M.A., Turner, A.C., Lipson, M., Gaeta, A.L., Nonlinear optics in photonic nanowires (2008) Opt. Express, 16 (2), pp. 1300-1320Siviloglou, G.A., Suntsov, S., El-Ganainy, R., Iwanow, R., Stegeman, G.I., Christodoulides, D.N., Enchanced thirdorder nonlinear effects in optical AlGaAs nanowires (2006) Opt. Express, 14 (20), pp. 9377-9384www.orc.soton.ac.uk/ofnrd.html, Optical Fibre Nanowires and Related Devices Group, University of SouthamptonCordeiro, C.M.B., Wadsworth, W.J., Birks, T.A., Russell, P.St.J., Engineering the dispersion of tapered fibers for supercontinuum generation with a 1064 nm pump laser (2005) Opt. Lett., 30 (15), pp. 1980-1982Wadsworth, W.J., Ortigosa-Blanch, A., Knight, J.C., Birks, T.A., Man, T.-P.M., Russell, P.St.J., Supercontinuum generation in photonic crystal fibers and optical fiber tapers: A novel light source (2002) J. Opt. Soc. Am. B, 19 (9), pp. 2148-2155Shi, L., Chen, X., Liu, H., Chen, Y., Ye, Z., Liao, W., Xia, Y., Fabrication of submicron-diameter silica fibers using electric strip heater (2006) Opt. Express, 14 (12), pp. 5055-5060Sagué, G., Baade, A., Rauschenbeutel, A., Blue-detuned evanescent field surface traps for neutral atoms based on mode interference in ultra-thin optical fibres (2008) New J. Phys., 10, pp. 113008+18Nayak, K.P., Melentiev, P.N., Morinaga, M., Le Kien, F., Balykin, V.I., Hakuta, K., Optical nanofiber as an efficient tool for manipulating and probing atomic fluorescence (2007) Opt. Express, 15 (9), pp. 5431-5438Xu, F., Horak, P., Brambilla, G., Optical microfiber coil resonator refractometric sensor (2007) Opt. Express, 15 (12), pp. 7888-7893Leon-Saval, S.G., Birks, T.A., Wadsworth, W.J., Russell, P.S.J., Supercontinuum generation in submicron fibre waveguides (2004) Opt. Express, 12 (13), pp. 2864-2869Tran, T.X., Biancalana, F., An accurate envelope equation for light propagation in photonic nanowires: New nonlinear effects (2009) Opt. Express, 17 (20), pp. 17934-17949Biancalana, F., Tran, Tr.X., Stark, S., Schmidt, M.A., Russell, P.S., Emergence of geometrical optical nonlinearities in photonic crystal fiber nanowires (2010) Physical Review Letters, 105, p. 09390

Optical And Physical Properties Of Er3+-yb3+ Co-doped Tellurite Fibers

In this work we present results of physical and optical properties of Er3+-Yb3+ co-doped tellurite glasses and fibers. The Double Clad Tellurite Fibers (DCTFs) are based on glasses with the composition: TeO2-WO3-Nb2O5-Na 2O-Al2O3-Er2O3-Yb 2O3. The DCTFs were fabricated by using the rod-in-tube technique and a Heathway drawing tower. The optical absorption spectra (ranging from 350 to 1750 nm) of these fibers were measured using an Optical Spectrum Analyzer (OSA). The emission spectra, around 1550 nm band, of these fibers (lengths varying from 1 to 60 cm) were obtained by using a 980nm diode laser pump. The optimal Amplified Spontaneous Emission (ASE) spectra were observed for fiber lengths ranging from 2 to 6 cm. The Er 3+/Yb3+ co-doped DCTFs show an efficient up-conversion process in comparison with the Er3+-doped DCTF. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).8120The Society of Photo-Optical Instrumentation Engineers (SPIE)Murugan, G.S., Suzuki, T., Ohishi, Y., Raman characteristics and nonlinear optical properties of tellurite and phosphotellurite glasses containing heavy metal oxides with ultrabroad Raman bands (2006) J. of Appl. Phys., 100, p. 023107Nandi, P., Jose, G., Ytterbium-doped P2O5-TeO2 glass for laser applications (2006) IEEE J. of Quat. Electron., 42, pp. 1115-1121Man, S.Q., Pun, E.Y.B., Chung, P.S., Tellurite glasses for 1.3 mm optical amplifiers" (1999) Opt. Comm., 168, pp. 369-373Wang, J.S., Vogel, E.M., Snitzer, E., Tellurite Glass: A New Candidate for Fiber Devices" (1994) Opt. Mat., 3, pp. 187-203Xu, S., Sun, H., Dai, S., Zhang, J., Jiang, Z., Upconversion luminescence of Tm3+/Yb3+-codoped oxyhalide tellurite glasses" (2005) Sol. St. Comm., 133, pp. 89-92Bookey, H.T., Lousteau, J., Jha, A., Gayraud, N., Thomson, R.R., Psaila, N.D., Li, H., Kar, A.K., Multiple rare earth emissions in a multicore tellurite fiber with a single pump wavelength" (2007) Opt. Express, 15, pp. 17554-17561Qin, G., Mori, A., Ohishi, Y., Brillouin lasing in a single-mode tellurite fiber" (2007) Opt. Lett., 32, pp. 2179-2181Zweig, A.D., Frenz, M., Romano, V., Weber, H.P., A comparative study of laser tissue interaction at 2.94 μm and 10.6 μm" (1988) Appl. Phys. B, 47, pp. 259-265Zhang, J., Dai, S., Wang, G., Sun, H., Zhang, L., Hu, L., Fabrication and emission properties of Er3+/Yb3+ codoped tellurite glass fiber for broadband optical amplification (2005) J. of Lum., 115, pp. 45-52Shixun, D., Tiefeng, X., Qiuhua, N., Xiang, S., Xunsi, W., Fabrication and gain performance of Er3+/Yb3+-codoped tellurite glass fiber (2008) J. of Rare Earths, 26, pp. 915-918Jakutis, J., Gomes, L., Amancio, C.T., Kassab, L.R.P., Martinelli, J.R., Wetter, N.U., Increased Er3+ upconversion in tellurite fibers and glasses by co-doping with Yb3+ (2010) Opt. Mat., 33, pp. 107-111Hruby, A., Evaluation of glass-forming tendency by means of DTA (1972) Czech J. Phys B, 22, pp. 1187-119

Epidemiologia do vírus da língua azul em rebanhos bovinos.

A Língua Azul é uma doença re-emergente que causa aborto em vacas, queda do desempenho reprodutivo, perda de condição corporal e redução na produção e leite. A ocorrência dessa doença está relacionada à presença de vetores transmissores. No Brasil, apesar da existência de poucos estudos sobre a ocorrência dos vetores dessa doença, levantamentos sorológicos indicam a circulação do vírus da Língua Azul em rebanhos bovinos, inclusive no Pantanal.bitstream/CPAP/55963/1/DOC85.pdfFormato Eletrônic

Micro-structured Er 3+-tm 3+ Co-doped Tellurite Fiber For Broadband Optical Amplifier Around 1550nm

Micro-structured Er 3+-Tm 3+ co-doped tellurite fiber with three rings of holes was fabricated using a soft glass drawing tower by a stack-and-draw technique. Amplified spontaneous emission (ASE) around 1550nm band were observed when pumped with both, 980nm and 790nm, lasers.6314Russell, P., Photonic crystal fibers (2003) Science, 299, pp. 358-362Knight, J.C., Photonic crystal fibers (2003) Nature, 424, pp. 847-851Kumar, V.V.R.K., George, A.K., Reeves, W.H., Knight, J.C., Russell, P.St.J., Omenetto, F.G., Taylor, A.J., Extruded soft glass photonic crystal fiber for ultrabroad supercontinuum generation (2002) Opt. Exp, 10 (25), pp. 1520-1525Chillcce, E.F., Cordeiro, C.M.B., Barbosa, L.C., Cruz, C.H.B., Er 3+-Tm 3+ co-doped tellurite fibers for broadband optical fiber amplifier around 1550nm band (2006) Opt. Fiber Technol., 12, pp. 185-195Chillcce, E.F., Rodriguez, E., Neves, A.A.R., Moreira, W.C., Cesar, C.L., Barbosa, L.C., Cruz, C.H.B., Tellurite photonic crystal fiber by a stack-and-draw technique (2006) J. Non-cryst. Solids, , accepted to publicationWhite, T.P., McPhedran, R.C., De Sterke, C.M., Botten, L.C., Steel, M.J., Confinement losses in microstructured optical fibers (2001) Opt. Lett, 26 (21), pp. 1660-1663Barbosa, L.C., Cruz, C.H.B., Cesar, C.L., Cordeiro, C.M.B., Chillcce, E.F., Production process of tellurite glass tubes, capillaries and rods Brazilian pending Patent No 018050002734Chillcce, E.F., Cordeiro, C.M.B., Rodriguez, E., Cruz, C.H.B., Cesar, C.L., Barbosa, L.C., Tellurite photonic crystal fiber with Er 3+-Tm 3+ for broadband optical amplifier in 1550nm (2006) Proc. of SPIE, 6116, p. 61160

Pbte Quantum Dots In Tellurite Glass Microstructured Optical Fiber

PbTe doped tellurite glass photonic optical fiber for non linear application were developed using rod in tube method in a draw tower. We follow the growth kinetics of the quantum dots in the optical fiber by High Resolution Transmission Electron Microscopy giving some results related with the growth kinetic of the same in function of time so much for optical fiber as for the glass bulk. Absorption peak near 1500 nm as observed and it was attributed the optical resonance due PbTe quantum dots in the core fiber.6902Tsunetomo, K., (1995) Nonlinear Opt, 13, p. 109Borrelli, N.F., Smith, D.W., (1994) J. Non-Cryst. Soi, 180, p. 25Lipovskii, A., Kolobkova, E.A., Petrikov, V., Kang, I., Olkhovets, A., Krauus, T., Thomas, M., Kycia, S., (1997) Appl. Phys. Lett, 71, p. 3406Reynoso, V.C.S., de Paula, A.M., Cuevas, R.F., Medeiros Neto, J.A., Alves, O.L., Cesar, C.L., Barbosa, L.C., (1995) Elect. Lett, 31 (12), pp. 1013-1014Rodrigues, E., Jimenez, E., Jacob, G.J., Neves, A.A.A., Cesar, C.L., Barbosa, L.C., (2005) Phisica E, 26, pp. 321-325Jacob, G.J., Cesar, C.L., Barbosa, L.C., Tellurite Glass Doped with PbTe Quantum Dots (2002) Physics and Chemistry of Glass, 43 C, pp. 250-253Jacob, G.J., Rodriguez, E., Barbosa, L.C., Cesar, C.L., Tellurite Glass Optical fiber doped with PbTe Quantum DotsPhotonics West 2005, The International Society for Optical Engineering SPIEEnomoto, Y., Tokuyama, M., Kawasaki, K., (1986) Act. Metall, 34, p. 2139Marqusee, J.A., Ross, J., (1984) J. Chem. Phys, 80, p. 536Lifshitz, E.M., Slyozov, V.V., (1961) J. Phys. Chem. Sol, 19, p. 3

Sistema de produção e utilização da mandioca em assentamentos rurais de Corumbá, MS.

Como base para estudos sobre a viabilidade de utilização de resíduos da cultura da mandioca (Manihot esculenta Crantz) para a alimentação de ruminantes na época de seca, foi avaliado o sistema de produção e de utilização dessa cultura em assentamentos rurais localizados no município de Corumbá, MS. A coleta de dados foi realizada por observação participante e por aplicação de questionários dirigidos a 235 produtores de base familiar residentes nos assentamentos Mato Grande, Paiolzinho, Tamarineiro II e Taquaral. Procurou-se identificar a influência de fatores sociais, econômicos e culturais sobre o processo produtivo e de utilização da mandioca nessas comunidades. Os resultados obtidos indicam a bovinocultura como a principal atividade econômica desenvolvida pelas famílias assentadas, seguida pela agricultura. A mandioca destaca-se como uma cultura importante para a região, tanto economicamente como para a segurança alimentar das famílias assentadas, com um grande percentual de famílias produtoras (69,7%). A parte aérea da mandioca vem sendo utilizada apenas como alimento fresco fornecido aos animais no momento da colheita. A necessidade de possuir triturador de forragem foi identificada pela própria comunidade como um dos principais fatores limitantes para a utilização dos resíduos da cultura da mandioca como subproduto da produção agrícola a ser empregado para alimentação de ruminantes.bitstream/CPAP/55940/1/BP70.pdfFormato Eletrônico

Gesneriaceae da Serra do Relógio, Descoberto, Estado de Minas Gerais, Brasil

The Serra do Relógio is located in the municipality of Descoberto, Zona da Mata in the State of Minas Gerais. There is two important conservation units in this region, Reserva Biológica da Represa do Grama and Reserva Particular do Patrimônio Natural Alto da Boa Vista. Both Conservation Units together cover a total area of ~403 ha of vegetation, mainly semi-deciduous seasonal forest. The Gesneriaceae is represented in the area by eight species, distributed in the genus Besleria (2 spp.), Nematanthus (3 spp.), Paliavana (1 spp.), Sinningia (1 spp.) and Vanhouttea (1spp.). We present descriptions, identification key, comments on taxonomy, distribution and ecology as well as photos of all recorded species.A Serra do Relógio está localizada no município de Descoberto, Zona da Mata no Estado de Minas Gerais. Há duas importantes Unidades de Conservação, a Reserva Biológica da Represa do Grama (RBRG) e a Reserva Particular do Patrimônio Natural Alto da Boa Vista (RPPNABV). Juntas abrangem uma área total de 402,6 hectares, sendo composta, predominantemente pela Floresta Estacional Semidecidual baixo-montana. Gesneriaceae está representada na área por oito espécies, distribuídas nos gêneros Besleria (2 spp.), Nematanthus (3 spp.), Paliavana (1 spp.), Sinningia (1 spp.) e Vanhouttea (1 spp.). Neste trabalho são apresentadas descrições, chave de identificação, comentários sobre taxonomia, distribuição e ecologia assim como fotos para todas as espécies