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A depressed cladding waveguide composed of 36 parallel tracks is inscribed in high purity 70TeO2-22WO3-8Bi2O3 glass by femtosecond laser operating at 1030 nm. The Sellmeier formula for the refractive index of the investigated glass is obtained for the range of 1170–2350 nm. The module of the negative refractive index change in a track is found to increase with increasing wavelength in the range of 640–2000 nm. The waveguide shows single mode behavior in the wavelength range of 1700–2100 nm with mode field diameter (MFD) of 20 μm. The propagation loss is predominantly due to scattering in the waveguide. Spectrum broadening as large as 503 nm was demonstrated in a 14 mm long waveguide pumped by femtosecond pulses at 1950 nm. In the low input pulse energy region, the spectrum broadening is well described by generalized nonlinear Shrodinger equation (GNLSE) taking into account Kerr and the Raman nonlinearities under the assumption of constant MFD along the waveguide. Under higher energy pumping, an extra broadening was observed that is attributed to the focusing effect of Kerr lens in the waveguide mode.

This Letter reports the experimental realization, for the first time to our knowledge, of lasing in an erbium-doped tellurite fiber at 2.72 µm. The key to the successful implementation was the use of advanced technology for obtaining ultra-dry preforms of tellurite glasses, as well as the creation of single-mode Er3+-doped tungsten–tellurite fibers with an almost imperceptible absorption band of hydroxyl groups, with a maximum of ∼3 µm. The linewidth of the output spectrum was as narrow as 1 nm. Our experiments also confirm the possibility of pumping the Er-doped tellurite fiber with a low-cost high efficiency diode laser at 976 nm.

A series of glass samples of the tungsten–tellurite system TeO2-WO3-Bi2O3-(4-x) La2O3-xEr2O3, x = 0, 0.4, 0.5, 0.7, 1.2, 2, 4 mol%, CEr = 0 - 15 × 1020 cm−3 were synthesized from high-purity oxides in an oxygen flow inside a specialized sealed reactor. In all samples of the series, an extremely low content of hydroxyl groups was achieved (~n × 1016 cm−3, more than 4 orders of magnitude lower than the concentration of erbium ions), which guarantees minimal effects on the luminescence properties of Er3+. The glasses are resistant to crystallization up to 4 mol% Er2O3, and the glass transition temperatures do not depend on the concentration of erbium oxide when introduced by replacing lanthanum oxide. Thin 0.2 mm plates have high transmittance at a level of 20% in the 4.7–5.3 µm range, and the absorption bands of hydroxyl groups at about 2.3, 3, and 4.4 µm, which are typical for ordinary tellurite glass samples, are indistinguishable. The introduction of erbium oxide led to an insignificant change in the refractive index. Er2O3-concentration dependences of the luminescence intensities and lifetimes near the wavelengths of 1.53 and 2.75 μm were found for the 4I13/2–4I15/2 and 4I11/2–4I13/2 /transitions of the Er3+ ion. The data obtained are necessary for the development of mid-infrared photonics, in particular, for the design of Er3+-doped fiber lasers.

We report novel functionalities of a very simple, robust, and low-cost optical metrology method for the reconstruction of an intensity profile and phase of pulses in the telecommunication range based on measuring the fundamental spectrum and two self-phase modulated spectra after a nonlinear element with Kerr nonlinearity. We demonstrate, for the first time, to the best of our knowledge, the possibility of implementing this method using a microstructured tellurite fiber (with a zero dispersion wavelength of 1.55 μ m and nonlinear coefficient >500 (W km)−1) as a nonlinear element for characterizing optical pulses with a wide range of parameters: wavelengths from O-band to L-band, durations from

Microresonator-based lasers in the two-micron range are interesting for extensive applications. Tm3+ ions provide high gain, therefore, they are promising for laser generation in the two-micron range in various matrices. We developed a simple theoretical model to describe Tm-doped glass microlasers generating in the 1.9–2 μm range with in-band pump at 1.55 μm. Using this model, we calculated threshold pump powers, laser generation wavelengths and slope efficiencies for different parameters of Tm-doped tellurite glass microspheres such as diameters, Q-factors, and thulium ion concentration. In addition, we produced a 320-μm tellurite glass microsphere doped with thulium ions with a concentration of 5·1019 cm−3. We attained lasing at 1.9 μm experimentally in the produced sample with a Q-factor of 106 pumped by a C-band narrow line laser.

Tellurium dioxide based glasses with a low hydroxyl groups concentration were synthesized in an atmosphere of dried oxygen from initial high purity oxides. Large high-quality optical elements were manufactured and investigated from the point of view of nonlinear propagation of ultrashort pulses in the mid-IR range. Optical homogeneity, thermophysical, optical, including nonlinear properties were studied.

Here we studied theoretically and experimentally the thermal frequency shift of whispering gallery modes (WGM) in silica and tellurite spherical microresonators. Temperature distributions and corresponding shifts of WGMs were calculated. The shift obtained in a silica microsphere generating optical frequency comb (OFC) with a width of >300 nm and independent estimates showed that thermal and Kerr effects made a comparative contribution. For a tellurite microsphere without OFC generation, the thermal effect dominated.

A depressed cladding waveguide, written by the femtosecond laser beam in the dry tellurite 70TeO 2 – 22WO 3 – 8Bi 2 O 3 glass allows obtaining octave-spanning supercontinuum in the 1.5 – 3.4 µm range under pumping at 2.2 µm by 260 fs pulses. Theoretical simulations of nonlinear propagation of the ultrashot pulses are in good agreement with experimental results.

We demonstrate 45-55 mW average output power at 2.3 microns in Tm3+-doped tellurite glass fiber laser pumped by a 794 nm multimode laser diode. To the best of our knowledge it is the highest 2.3 micron output from a fiber laser, and it is already a practically significant power that can be used in various applications.

Compact fiber-based sources generating optical pulses with a broadband spectrum in the mid-IR range are in demand for basic science and many applications. Laser systems producing tunable Raman solitons in special soft-glass fibers are of great interest. Here, we report experimental microstructured tellurite fibers and demonstrate by numerical simulation their applicability for nonlinear soliton conversion in the mid-infrared (-IR) range via soliton self-frequency shift. The fiber dispersion and nonlinearity are calculated for experimental geometry. It is shown numerically that there are two zero dispersion wavelengths for the core size of 2 &mu, m and less. In such fibers, efficient Raman soliton tuning is attained up to a central wavelength of 4.8 &mu, m using pump pulses at 2.8 &mu, m.

The tremendous progress made in recent years in the production of tellurite glasses has led to the development of different optical elements and devices on their basis such as microresonators and microlasers. The investigation of tellurite glass microresonators is of great importance for many potential applications. We studied theoretically and experimentally the nonlinear thermo-optical effects in tellurite glass microresonators under continuous-wave laser pumping. We calculated the temperature distributions for both, steady-state and transient non-stationary regimes and simulated shifts of the resonant wavelengths of whispering gallery modes. We produced Tm-doped tellurite glass microspheres and measured the resonant wavelength shifts as functions of the heat power. Our experimental results are in a good agreement with the theoretical predictions.

The temperature-dependent heat capacity of three high-purity (1–x)(0.75TeO2–0.25WO3) + xLa2O3 tellurite glass samples (x = 0.02, 0.04, and 0.06) has been determined by dynamic calorimetry in the range 320–1000 K. The experimental devitrification and heat capacity data have been used to evaluate standard thermodynamic functions: C o (T), enthalpy, entropy, and Gibbs energy in glassy and supercooled liquid states. We have demonstrated model-parameter similarity of properties in a statistical approach and found correlation relationships for parameters as functions of composition, which make it possible to predict the thermodynamic functions of unexplored glasses of this series. We have identified crystallization-resistant compositions of (1–x)(0.75TeO2–0.25WO3) + xLa2O3 glasses as a basis for the development of optically active elements.

High-purity tungstate-tellurite glasses doped with molybdenum, lanthanum or bismuth oxides were investigated from a point of view promising medium for nonlinear optical devices fabrication. A tubular-like architecture was employed for fabrication of waveguides in the of tellurite glasses, in which refractive index change is negative under femtosecond laser writing at 1028 nm. Thermal, nonlinear optical properties and optimal laser writing conditions were determined. The glasses revealed a very high stability against crystallization, high transparency in the visible, near- and mid-IR regions, large values of Kerr nonlinear coefficient that are within the range of (4.3 ÷ 5.4)·10− 6 cm2/GW. The highest values of the nonlinear coefficient were found for bismuth containing glasses. The single mode waveguide with propagation loss of 0.15 dB/cm at 1064 nm was inscribed in tungstate-tellurite glass.

A series of samples of high-purity glasses TeO 2 -WO 3 -La 2 O 3 -Er 2 O 3 -Bi 2 O 3 with different mole content of Er 2 O 3 was synthesized. The total content of the 3d-transition metals impurities did not exceed 0.1–2 ppm wt., the hydroxyl groups absorption near ~ 3 μm was as low as 0.001–0.01 cm − 1 . The glasses have been studied by differential scanning calorimetry. Glass transition temperatures were determined; for the highest Er 2 O 3 concentrations the thermal effects of crystallization were observed at the heating rate of 5 K/min. The temperature dependences of heat capacity C ° p = f ( T ) in the range of 320–1050 K were found. Using the experimental data the standard thermodynamic functions were calculated: enthalpy H °( T ) − H °(0), entropy S °( T ) − S °(0) and Gibbs energy G °( T ) − G °(0) in vitreous and “supercooled liquid” states. Model and parametric similarity of properties within the framework of statistical approach with determined correlation dependencies of parameters on composition makes it possible to predict the thermodynamic functions for other compositions of glasses within the system.

High-purity TeO 2 –ZnO, TeO 2 –ZnO–Na 2 O and TeO 2 –ZnO–La 2 O 3 –Na 2 O glasses have been characterized in terms of material applicability for magneto-optical devices. Glasses with extremely low content of absorbing impurities of 3d-transition metals and hydroxyl groups have been prepared inside a sealed silica glass chamber in a flow of purified oxygen. Magneto-optical properties, including spectral dependence of the Verdet constant in the 450–1561 nm range and magnetic figure of merit, crystallization stability and optical properties in the IR range were studied.

The aim of this investigation is the search of novel promising materials for solid-state and fiber lasers emitting in the spectral range 2÷3 microns, i.e. out of the range where the well-developed rare-earth doped silica fibers can successfully operate. We have stopped our choice on tellurite and calcium aluminate glasses. In contrast to silica glasses, both these glass types can contain high (>1021 cm−3) amounts of rare earth dopants. In contrast to ZBLAN glass that is widely used for mid-infrared fiber lasers, both tellurite and aluminate glasses can be quite stable to air moisture. Furthermore, calcium aluminate glasses are prominent for their extraordinary mechanical properties (better than those of fused silica).

Differential scanning calorimetry (DSC) characterization of tellurite glasses doped with lanthanum oxide, which improves their crystallization resistance, has revealed a phase transformation specific to such glasses, in which partial crystallization of a sample is followed by melting of the crystals formed. The experimentally observed dependence of the decrease of crystallization–melting peaks across a series of disperse samples of (TeO2)0.72(WO3)0.24(La2O3)0.04 glass with increasing particle size upon extrapolation to the size of a bulk sample has been used to assess the crystallization resistance of tellurite glasses for optical applications. The assessment technique comprises DSC characterization of particle-size-classified glass samples and the use of a mathematical model for obtaining the degree of crystallization as a function of temperature and time, α(T, t) through analysis of nonisothermal DSC peaks representing a partial glass crystallization process passing into melting. The crystallization resistance of glass is estimated by extrapolating the maximum α values as a function of particle size to a preform size. Tested for (TeO2)0.72(WO3)0.24(La2O3)0.04 glass, the technique offers the possibility of selecting preforms for producing fibers from compositionally new, chemically pure tellurite glasses at a given phase purity level.

In this paper we present for the first time the 2.3 µm thulium doped tellurite glass fiber laser with practically significant output parameters. The 200 mW average and 400 mW peak output powers at 2.3 µm were obtained using a 30 cm long fiber pumped by a 794 nm fiber coupled commercial laser diode.

High-purity and well-dehydrated (hydroxyl absorption at 3.3 µm no more than 0.02 cm−1) rare-earth ions doped glasses of ZnO–TeO2 system were synthesized. The luminescent properties of Tm3+, Er3+, Ho3+ and Dy3+ ions were investigated in the prepared glass samples. The performed investigations had shown that zinc-tellurite glass is quite a promising host for 2.3 µm Tm3+ and 2.7 µm Er3+ lasers. Pulsed 2.3 µm laser action with output energy up to ~ 12 mJ was demonstrated in bulk Tm3+ doped tellurite glass. The losses in the fiber made of Tm-doped glass were not exceeding 0.8 dB/m (~ 2 × 10−3 cm−1) in the spectral range of 2.1/2.7 µm.

Ultrabroadband amplification and two-color CW lasing simultaneously near 1.9 μm and 2.3 μm in a Tm3+-doped tellurite fiber were demonstrated experimentally, for the first time to the best of our knowledge. A low-loss Tm3+-doped core fiber from TeO2–ZnO–La2O3–Na2O glasses stable against crystallization was produced by a special technique, providing a low concentration of hydroxyl groups. Supercontinuum from a highly GeO2 doped silica fiber pumped by an Er fiber laser system was used as a seed for an amplifier. A maximum gain of 30 dB and 7 dB was measured at 1.9 μm and 2.3 μm, respectively. We report detailed experimental and theoretical studies, which are in a very good agreement, of laser amplification and generation in the manufactured fiber with carefully measured and calculated parameters. A quantitatively verified numerical model was used to predict power scalability at 2.3 μm in schemes with optimized parameters at increased pump power. The presented results show that a high-quality tellurite fiber is a promising candidate for developing lasers in the 2.3 μm atmospheric window which are particularly relevant for applications in gas sensing, eye-safe laser radars, breath analysis, remote sensing and stand-off trace gas detection.

The possibility of low-loss erbium or thulium doped tellurite fibers application for laser operation mainly in the 2–3 microns range was studied. High-purity samples were produced and characterized. Photoluminescence spectra were measured, and amplification of seeded signal was observed experimentally. Numerical simulations of laser operation showed potential applicability of the designed samples in the range of interest.

We manufactured and characterized a low-loss gain fiber based on high-purity TeO2–ZnO–La2O3–Na2O undoped glass for 100-μm cladding and TeO2–ZnO–La2O3–Na2O glass for 10-μm core doped with 0.24 mol% Er2O3. To confirm that the produced fiber is a promising active element for the infrared range, we demonstrated experimentally broadband laser amplification and CW generation at the 4I13/2 → 4I15/2 transition at 1555 nm with a single-mode diode pump at 975 nm at the 4I15/2 → 4I11/2 transition. We developed a numerical model calibrated to the experimental data for prediction and optimization of laser characteristics in schemes with different parameters. The model describes single- wavelength lasing as well as dual-wavelength cascade lasing at 1555 nm and 2800 nm. It was shown numerically that for the optimized parameters, the maximum slope efficiency at 2800 nm at the 4I11/2 → 4I13/2 transition can reach ~20%. The maximum calculated efficiency at 1555 nm exceeds 30%.

We propose two-color pump schemes for CW Er-doped tellurite fiber lasers and amplifiers in the 2.7–2.8 µm range at the transition. The use of the first pump wavelength of 0.98 µm () or 1.56 µm () and the second pump wavelength of 1.7 µm () allows obtaining gain at relatively low powers. We have performed a theoretical study of laser operation under two-color pump on the basis of the experimentally measured parameters of the specially prepared Er-doped tellurite fiber from TeO2–ZnO–La2O3–Na2O glass. It has been shown numerically that, for an optimal fiber length, the small-signal gain may exceed 18 dB and laser generation may be achieved with a relatively low threshold of a few hundreds of mW and a maximum slope efficiency can be ~40%. In addition, we have demonstrated in experiment a prototype of the power-scalable Er silica fiber source generating simultaneously near 1.56 and 1.7 µm, which may be used for implementing the proposed two-color pumped laser and amplifier.

0.72TeO 2 –0.24WO 3 –0.04La 2 O 3 glass and melt were studied by differential scanning calorimetry (DSC) method. Heat capacity and transition temperature of the glass were precisely found. The improved comparative technique for DSC-measurement of thermal conductivity coefficient of vitreous state of the sample has been developed. A model-statistical approach was used for processing the experimental data to calculate parameters of elementary excitations, that allowed to find out a complete set of thermal properties along with density and coefficient of thermal expansion.

A simple design of a fiber laser system for generating high-quality pulses with a duration of order 100 fs with ultrabroad wavelength tunability in the 2–5 μm range is discussed. This design incorporates conventional fs near-IR lasers and specially developed tungstate–tellurite fibers with two zero-dispersion wavelengths (ZDW) and relies on nonlinear wavelength conversion via either soliton self-frequency shift (SSFS) or red-shifted dispersive wave (DW) generation. The fiber parameters needed for such optical conversion have been scanned numerically and showed a possibility of SSFS beyond 4 μm and of DW generation beyond 5 μm. We have also studied and prepared tungstate–tellurite glasses and preforms that are highly stable against crystallization, exhibit extremely low level of hydroxyl groups absorption, and from which the suspended-core two-ZDW fibers can be manufactured.

We have demonstrated numerically the possibility to obtain ultrashort laser pulses in the range beyond 4 microns due to soliton self-frequency shift and red-shifted dispersive wave generation in a suspended-core fiber made of specially synthesized high-purity low-loss Te 2 O 3 -WO 3 -La 2 O 3 glass pumped by a standard fs pump laser source at 2 microns.

In this study, we propose a widely tunable in the 1.6-2.65 μm range femtosecond fiber laser source, generating high-quality sech-shaped pulses with the duration of order 100 fs. Experimental setup contains hybrid all-fiber Er/Tm pump laser generating 150 fs pulses of 2 nJ in Erbium (1.56 μm) channel and 125 fs pulses of 4 nJ in Thulium (2 μm) channel respectively. This laser source was coupled to a 50 cm piece of suspended-core microstructured TeO 2 -WO 3 - La 2 O 3 glass fiber with launching efficiency of about 10%. We have observed Raman self-frequency shifting solitons in this fiber with maximum red shift of 2.25 μm for Erbium channel and 2.65 μm for Thulium channel. By varying energy of pump pulses, solitons can be tuned in broadband spectral region. We have made theoretical studies of nonlinear pulse dynamics in the tellurite fiber with carefully measured and calculated parameters. Numerical simulation is in a very good agreement with the experiment

The possibility of producing tungsten-telluride glasses using plasma chemical vapor phase deposition using corresponding chlorides as source components has been experimentally demonstrated. Homogeneous layers in the entire vitrification range of the TeO2-WO3 system have been obtained. The concentration of metal impurities in the deposited layers does not exceed n × 10−4 wt % that is comparable with their concentration in the source chlorides. Using the techniques of differential scanning calorimetry and Raman scattering, it has been shown that, at the melting stage, the layers obtained are vitreous and comparable in their characteristics with the glasses fabricated using traditional techniques.

TeO 2 –WO 3 (TW), TeO 2 –WO 3 –La 2 O 3 (TWL), TeO 2 –WO 3 –La 2 O 3 –Bi 2 O 3 (TWLB) and TeO 2 –ZnO–Na 2 O–Bi 2 O 3 (TZNB) glasses were produced by high-purity oxide mixtures melting in platinum or gold crucible at 800 °C in the atmosphere of purified oxygen. The total content of Cu, Mn, Fe, Co and Ni impurities was not more than 0.1–0.5 ppm wt in the initial oxides and glasses. The stability of TZNB glasses to crystallization, characterized by (T x − T g ) value more than 150 °C, was demonstrated by DSC measurements at heating rate 10 K/min. In the case of La 2 O 3 -containing glasses the thermal effects of both crystallization and fusion of the crystallized phases were not observed. The hydroxyl groups absorption coefficients of pure tellurite glasses at the maximum of the absorption band (λ ~ 3 μm) were in the region of 0.012–0.001 cm −1 . The optical absorption losses, measured by the laser calorimetry method at λ = 1.56 and 1.97 μm, did not exceed 100 dB/km.

By melting a mixture of high-purity oxides in a platinum crucible under flowing purified oxygen, we have prepared (TeO2)0.75(WO3)0.25 glass with a total content of 3d transition metals (Fe, Ni, Co, Cu, Mn, Cr, and V) within 0.4 ppm by weight, a concentration of scattering centers larger than 300 nm in size below 102 cm−3, and an absorption coefficient for OH groups (λ ∼ 3 μm) of 0.008 cm−1. The absorption loss in the glass has been determined to be 115 dB/km at λ = 1.06 μm, 86 dB/km at λ = 1.56 μm, and 100 dB/km at λ = 1.97 μm. From reported specific absorptions of impurities in fluorozirconate glasses and the impurity composition of the glass studied here, the absorption loss at λ ∼ 2 μm has been estimated at ≤100 dB/km. The glass has been drawn into a glass-polymer fiber, and the optical loss spectrum of the fiber has been measured.

A 2.3 ?m laser action, as well as a cascade 2.3 ?m and a 1.9 ?m lasing in a diode-pumped tellurite glass fiber, is demonstrated for the first time.

A large mode area depressed cladding waveguide was inscribed by a femtosecond laser beam in bulk of high purity 70TeO2-22WO3-8Bi2O3 glass. Non-linear propagation of femtosecond pulses in the single mode waveguide with mode field diameter of 12 μm was investigated under input at 1030 nm wavelength. The highest peak value of a Raman-gain coefficient of all the tellurite glasses was measured (1.2x10−9 cm/W). The dispersion of the refractive index was obtained in the range of 1170-2300 nm. Spectrum broadening of up to 160 nm at the −10 dB level was observed under input pulse energy as low as 84 nJ in a 14 mm long waveguide. The spectrum broadening was numerically simulated, and it was found that both the Kerr and the Raman nonlinearities result to comparable contributions to the spectrum transformation.

This letter demonstrates the passive Q-switching possibility of a 2.3 µm Tm-doped tellurite glass laser with the help of a Fe2+:ZnS saturable absorber. In contrast to Cr2+—doped materials, this saturable absorber is transparent at the laser pump wavelengths (0.69 or 0.8 µm). Pulses as short as 150–200 ns were formed.

We report the preparation of a high-purity optical-quality four-component glass of composition 68TeO2 — 22WO3 — 8La2O3 — 2Bi2O3, containing (2.7±0.5)×10-5 mol % OH groups. Its refractive index has been determined in the range 0.9 — 5.45 μm using interference refractometry. The data are used to assess the dispersion and guidance characteristics of microstructured optical fibres potentially attractive for supercontinuum generation in the range 1 — 5 μm

The absorption spectra of (TeO2)0.78(WO3)0.22 glasses containing 0.01–1.0 wt % NiO have been measured at wavelengths from 450 to 2700 nm, and the spectral dependence of the extinction coefficient of Ni2+ in the glasses has been obtained. In the absorption bands centered at 810 and 1320 nm, the extinction coefficient is 20.2 ± 0.8 cm−1 (870 ± 35 dB/(km ppmw)). According to the spectral range of its absorption and its extinction coefficient, nickel is a strongly absorbing impurity in tellurite glasses. The present results can be used to formulate sound nickel concentration limits in tellurite glasses for fiber-optic applications.

A study of high-purity TeO2-ZnO based tellurite glasses doped with Er3+, Dy3+ or Tm3+ that could be used as laser media in the 2-3 μm spectral range is presented. The glasses are prepared by melting the oxides mixture inside a silica glass reactor in an atmosphere of purified oxygen. The low level of hydroxyl groups absorption allowed to measure correctly the luminescence decay characteristics of the dopants. The rare-earth ions absorption bands, the luminescence spectra and kinetic characteristics of emission from the levels 4I11/2, 4I13/2 of Er3+, 6H13/2 of Dy3+ and 3H4, 3H5, 3F4 of Tm3+ ions are investigated. The results confirm the high potential of tellurite glasses as an active media for bulk, planar waveguide and fiber lasers.

Tellurium oxide-zinc oxide glass batches have been prepared through chemical vapor deposition from tellurium and zinc alkyl compounds in an oxyhydrogen flame onto the lateral surface of rotating cylindrical substrates. The composition of the deposits has been shown to be determined by the relative amounts of the metalorganic precursors in the gas phase. Varying the deposition conditions, we obtained both amorphous and crystalline deposits, with concentrations of metallic impurities below 1 ppmw. Melting the deposits, we prepared high-purity (TeO2)1 − x (ZnO) x (0.15 ≤ x ≤ 0.35) glasses.

We present low-loss tungstate-tellurite fibers doped with Er3+ for laser operation near 2.7 μm. Two “ultra-dry” preforms with cores of TeO2-WO3-La2O3-Bi2O3 glasses doped with 0.4 and 4 mol% of Er2O3 and undoped TeO2-WO3-La2O3 claddings were produced. High-quality multimode fibers were fabricated and characterized. Photoluminescence spectra of about 2.7 μm (4I11/2 → 4I13/2 transition) and about 1.6 μm (4I13/2 → 4I15/2 transition) were measured under excitation by diode pumping at 975 nm (4I15/2 → 4I11/2 transition). The production test and the theoretical investigation of gain-switched laser generation showed potential applicability of the designed samples in the spectral range of interest. Prospective application of single-mode fibers based on the developed glass preforms was also simulated. A feasibility of pulse train generation was demonstrated even for a rough choice of parameters, which is very encouraging for experimental implementation.

Tm3+ doped TeO2-based well-dehydrated glasses were synthesized and investigated. The analysis of their spectral and relaxation properties have showed that these glasses can be a suitable host for bulk and fiber lasers emitting at ~2.3 µm wavelength (3H4–3H5 Tm3+ transition). Laser action in the bulk glass sample was demonstrated.

Suspended core microstructured optical fibers were fabricated of high purity TeO2-WO3-La2O3 glass. The broadband emission with 1300 nm bandwidth was successfully generated in 0.8 m of fiber using 2 nJ femtosecond laser as a source.

We demonstrate a fibre laser source generating ultrashort pulses tunable in the range 2-2.5 μm. The source is based on a hybrid Er/Tm fiber laser system and microstructured suspended-core tellurite fiber where Raman soliton shifting occurs. Nonlinear soliton dynamics is studied and possibility of tuning beyond 3 μm is shown.

Thermally induced depolarization of radiation introduced by a system of two optical elements separated by a quartz rotator has been analyzed. The conditions of full compensation of thermally induced depolarization for two nonidentical optical elements have been found. The model experiment has demonstrated that full compensation in two optical elements of different materials is possible without a quartz rotator between them.

Different types of optical fibers with losses less than 100 dB/km were produced from high-purity tungstate-tellurite glasses. The microstructured fiber for supercontinuum generation in the range 1-5 µm with optical loss of 4 dB/m has been fabricated.