Doped Glass Fiber Research Articles

Ho3+ doped fluoroaluminate glass fibers for 2.9 µm lasing

Ho3+ doped fluoroaluminate glass fibers based on chemically durable AlF3–BaF2–YF3–PbF2–MgF2–CaF2 glasses are fabricated by using a rod-in-tube method. By using an 84 cm long Ho3+-doped fluoroaluminate glass fiber as the gain medium and a 1120 nm fiber laser as the pump source, lasing at 2868 nm is obtained, the maximum unsaturated power is about 57 mW for a pump power of 1224 mW, and the corresponding slope efficiency is ~5.1%. The effect of the fiber length on lasing at 2868 nm is also investigated. Our results show that Ho3+-doped fluoroaluminate glass fibers are promising gain media for 2.9 µm laser applications.

Advances in Single-Crystal Fibers and Thin Rods Grown by Laser Heated Pedestal Growth

Single-crystal fibers are an intermediate between laser crystals and doped glass fibers. They have the advantages of both guiding laser light and matching the efficiencies found in bulk crystals, which is making them ideal candidates for high-power laser and fiber laser applications. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc.) and a polycrystalline clad of yttrium aluminum garnet (YAG) that will exhibit good wave guiding properties. Direct growth or a combination of growth and cladding experiments are described. Scattering loss measurements at visible wavelengths, along with dopant profile characterization with damage threshold results, are also presented. For single-pass amplification, a single-pass linear gain of 7.4 was obtained for 29 nJ pulses of 5 ns duration at 1 MHz repetition rate. We also obtained a laser efficiency of over 58% in a diode-pumped configuration. These results confirm the potential for single-crystal fibers to overcome the limitations of the glass fibers commonly used in fiber lasers, making them prime candidates for high-power compact fiber lasers and amplifiers.

Optical decoherence and spectral diffusion in an erbium-doped silica glass fiber featuring long-lived spin sublevels

Understanding decoherence in cryogenically-cooled rare-earth-ion doped glass fibers is of fundamental interest and a prerequisite for applications of these material in quantum information applications. Here we study the coherence properties in a weakly doped erbium silica glass fiber motivated by our recent observation of efficient and long-lived Zeeman sublevel storage in this material and by its potential for applications at telecommunication wavelengths. We analyze photon echo decays as well as the potential mechanisms of spectral diffusion that can be caused by coupling with dynamic disorder modes that are characteristic for glassy hosts, and by the magnetic dipole-dipole interactions between $Er^{3+}$ ions. We also investigate the effective linewidth as a function of magnetic field, temperature and time, and then present a model that describes these experimental observations. We highlight that the operating conditions (0.6 K and 0.05 T) at which we previously observed efficient spectral hole burning coincide with those for narrow linewidths (1 MHz) { an important property for applications that has not been reported before for a rare-earth-ion doped glass.

Enhanced radiation dosimetry of fluoride phosphate glass optical fibres by terbium (III) doping

Fluoride phosphate (FP) glass fibres have been developed for radiation dosimetry based on the mechanism of optically stimulated luminescence (OSL). Doping with Tb3+ ions improved the materials sensitivity; for samples melted in oxidising conditions, OSL intensity was increased from 8.8 × 105 cnts/g/Gy for undoped glass to 812.3 × 105 cnts/g/Gy for Tb3+-doped glass. The radiation sensor performance of Tb3+-doped glass fibres under both beta and X-ray irradiation demonstrated the capability of the fibres for radiation dosimetry applications.

Investigation of upconversion luminescence in Yb3+/Tm3+/Ho3+ triply doped antimony-germanate glass and double-clad optical fiber

The optical properties of novel antimony-germanate glass and optical fiber co-doped with Yb3+/Tm3+/Ho3+ ions were presented. White light luminescence in glass was observed as a result of energy transfer with upconversion between donor (Yb3+) and acceptors (Tm3+, Ho3+) ions under 976 nm excitation. The double-clad optical fiber with off-set core co-doped with Yb2O3/Tm2O3/Ho2O3 system was fabricated using a modified rod-in-tube technique. In glass co-doped with 0.5 mol%Yb2O3/0.1 mol%Tm2O3/0.2 mol%Ho2O3 the spectral distribution of three luminescence bands (478, 545 and 660 nm) corresponds to x = 0.35 and y = 0.32 CIE coordinates. In comparison to glass the optical fiber emission are located in the green region (CIE, x = 0.37, y = 0.49).

Theoretical study of population inversion in active doped MIR chalcogenide glass fibre lasers (invited).

We study the mechanism of the population inversion in mid-infrared fibre lasers based on a chalcogenide glass host doped with active lanthanide ions. Three lanthanide dopant ions are considered: terbium, dysprosium and praseodymium. We predict the relevant trivalent ion level populations and gain. The simulation parameters were obtained by fabricating and optically characterising a series of trivalent ion doped chalcogenide glass samples. We also provide simple analytical expressions that aid the design of the cascade lasing process.

Defects induced in Yb3 +/Ce3 + co-doped aluminosilicate fiber glass preforms under UV and γ-ray irradiation

A set of Ce-/Yb-co-doped silica optical fiber preform cores, differing in terms of dopant concentrations are studied by Electron Paramagnetic Resonance (EPR) spectroscopy before and after irradiation of the samples with excimer UV laser light and γ-rays. Evidence of Yb3+ clustering in the case of high Yb content samples is observed on as prepared samples regardless of the presence of Ce3+ ions. Si-E′ and Al-OHC centers were identified upon photon irradiation. The results are correlated to the micro-structural origin of the photodarkening process occurring in Ce–Yb doped glass fibers.

Coilable single crystals fibers of doped-YAG for high power laser applications

Single crystal fibers are an intermediate between laser crystals and doped glass fibers. They have the advantages of both guiding laser light and matching efficiencies found in bulk crystals, which make them ideal candidates for high-power laser and fiber laser applications. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc.) that will exhibit good wave guiding properties. Direct growth or a combination of growth and cladding experiments are described. Scattering loss measurements at visible wavelengths along with dopant profile characterization are also presented. Laser characterization for these fibers is in progress.

550-mW Output Power From a Narrow Linewidth All-Phosphate Fiber Laser

We present a compact monolithic all-phosphate glass fiber laser with up to 550 mW of output power operating on a single longitudinal mode. We measured a linewidth of less than 60 kHz and relaxation oscillation peak amplitudes below -100 dB/Hz without active RIN-supression. The laser cavity has been formed by inscribing fiber Bragg gratings (FBG) directly into heavily Er3+ Yb3+ doped phosphate glass fiber using femtosecond laser pulses and a phasemask. The compact form factor and higher output power combined with the low noise and narrow line width characteristic make this laser an ideal candidate for ranging, interferometry and sensing applications.

Comparison between Analytical Solution and Experimental Setup of a Short Long Ytterbium Doped Fiber Laser

In this research, Amplified Spontaneous Emission (ASE) spectrum characteristics for a highly Yb3+ doped glass fiber with different pump powers and pump wavelengths are scrutinized. ASE spectral profile and wavelength shift corresponding to different optical fiber lengths are measured. Highly-doped Yb3+ fiber lasers in a linear-cavity are both experimentally and analytically investigated. Rate equations are solved using quasi-numerical models. Numerical results are reported for wide range of operating conditions to enable design optimization. The model takes into account the scattering loss and the distributed laser loss power density in strongly pump condition. The effects of various parameters such as pump power, pump wavelength, signal wavelength and fiber length on the output power and laser threshold are studied. Theoretical results are shown to be in good agreement with the experimental data.

Signal amplification in rare-earth doped heavy metal germanium tellurite glass fiber

Rare-earth doped heavy metal germanium tellurite (NZPGT) glass fibers with lower maximum phonon energy of 793 cm−1 and UV-sensitivity property have been designed and fabricated. Bright and compact upconversion traces have been observed in Er3+/Yb3+ and Tm3+/Yb3+ codoped NZPGT glass fibers, which exhibit favorable flexibility and excellent thermal stability, indicating that the NZPGT glasses are a desirable candidate for fiber amplifiers. The Er3+/Yb3+ codoped NZPGT glasses present a broad emission at ~1.5 μm with the FWHM of 72.7 nm, and the maximum internal gain of 12.59 dB with a remarkable gain coefficient of 2.38 dB/cm in the C-band were achieved in a Er3+/Yb3+ codoped NZPGT glass fiber. The efficient three-photon blue and two-photon near-IR upconversion emissions of a Tm3+/Yb3+ codoped NZPGT glass fiber demonstrate that low phonon energy NZPGT glasses have promising potential applications in Tm3+ single-doped glass fibers for S-band signal amplification, and the further development of O- and U-band fiber amplifiers and lasers in Pr3+ and Ho3+ doped NZPGT glass fibers.

Scalable side-pumped, gain-guided index-antiguided fiber laser

Single-mode laser action has been demonstrated in a gain-guided, index-antiguided (GG IAG) Nd3+ doped phosphate glass fiber through the use of a diode side-pumping scheme. This pump technique can allow for length scaling of diode-pumped GG IAG fibers and therefore true power scaling of the GG IAG concept. Near-Gaussian beam quality was demonstrated with beam M2 of 1.4.

Feedback controlled laser system for safe and efficient reshaping of nasal cartilage

Laser septochondrocorrection (LSC) is a non-invasive, bloodless, painless procedure which takes only 10 minutes to complete and can be performed in outpatient settings. The efficacy and safety of this technology can be guarantied with the feed-back control system monitoring tissue characteristics in the course of laser treatment. Laser medical equipment for septochondrocorrection includes an Erbium doped glass fiber laser, special instrument, opto thermo mechanical contactor, and feed back control system measuring temperature on the nasal septum surface and switching the laser off when preset value of temperature is achieved. To the date LSC procedure has been applied for 380 patients, aging from 12 until 68 years. The new laser equipment LRC-701 manufactured by Arcuo Medical Inc. was tested for 106 patients in Moscow and for 64 patients in Crete. The positive results habe been obtained for 95 percent of the patients with two years follow-up. No age limitation, no complications and negative secondary effects were observed.

Rare-earth ions doped heavy metal germanium tellurite glasses for fiber lighting in minimally invasive surgery

In Er(3+)/Yb(3+) codoped Na(2)O-ZnO-PbO-GeO(2)-TeO(2) (NZPGT) glass fiber, a clear and compact green upconversion amplified spontaneous emission (ASE) trace is observed, and the NZPGT glasses are proved to be a desirable candidate in fabricating low-phonon energy fiber. Intense green upconversion luminescence of Er(3+), balanced green and red upconversion emissions of Ho(3+), and dominant three-photon blue upconversion fluorescence of Tm(3+) have been represented. By varying the excitation power of 974 nm wavelength laser diode, a series of green and white fluorescences have been achieved in Tm(3+)/Er(3+)/Yb(3+) and Tm(3+)/Ho(3+)/Yb(3+) triply doped glass systems, respectively. These results reveal that high-intensity blue, green, and white upconversion ASE fluorescences, which can be adopted for lighting in minimally invasive photodynamic therapy and minimally invasive surgery, are reasonable to be expected in rare-earth doped NZPGT glass fibers.

Modelling of a simple Dy3+ doped chalcogenide glass fibre laser for mid-infrared light generation

A simple Dy3+-doped chalcogenide glass fibre laser design for mid-infrared light generation is studied using a one dimensional rate equation model. The fibre laser design employs the concept of cascade lasing. The results obtained demonstrate that efficient cascade lasing may be achieved in practice without the need for fibre grating fabrication, as a sufficient level of feedback for laser action is provided by Fresnel light reflection at chalcogenide glass fibre–air interfaces. Further enhancement of the laser efficiency can be achieved by terminating one of the fibre ends with a mirror. A numerical analysis of the effect of the Dy3+ doping concentration and fibre loss on the laser operation shows that with 5 W of pump power, at 1.71 μm wavelength, output powers above 100 mW at ∼ 4.5 μm wavelength can be achieved with Dy3+ ion concentrations as low as 3 × 1019 cm−3, when fibre loss is of the order 1dB/m.

Deformation micromechanics of a model cellulose/glass fibre hybrid composite

Abstract Interfacial stress transfer in a model hybrid composite has been investigated. An Sm3+ doped glass fibre and a high-modulus regenerated cellulose fibre were embedded in close proximity to each other in an epoxy resin matrix dumbbell-shaped model composite. This model composite was then deformed until the glass fibre fragmented. Shifts of the absolute positions of a Raman band from the cellulose fibre, located at 1095 cm−1, and a luminescence band from a doped glass fibre, located at 648 nm, were recorded simultaneously. A calibration of these shifts, for both fibres deformed in air, was used to determine the point-to-point distribution of strain in the fibres around the breaks in the glass fibre. Each break that occurred in the glass fibre during fragmentation was shown to generate a local stress concentration in the cellulose fibre, which was quantified using Raman spectroscopy. Using theoretical model fits to the data it is shown that the interfacial shear stress between both fibres and the resin can be determined. A stress concentration factor (SCF) was also determined for the regenerated cellulose fibre, showing how the presence of debonding reduces this factor. This study offers a new approach for following the micromechanics of the interfaces within hybrid composite materials, in particular where plant fibres are used to replace glass fibres.

S271 – The Use of Erbium Doped Glass Fiber Laser in Septoplasty

Objectives To evaluate the efficacy of Erbium doped glass fiber laser in patients undergoing cartilage reshaping under local anesthesia. Methods A prospective study was conducted in 64 patients undergoing laser nasal septal cartilage reshaping. Micro-surgical sponges soaked in a tetracaine solution plus adrenalines were applied in each side of the nose for 10 minutes before the procedure. The cartilage of nasal septum was straightened and fixed in the median position using a modified nasal speculum. An optothermomechanical contactor with transparent indenter and thermocouple sensor was placed on septal regions of maximum mechanical stress. Patients were asked to evaluate the severity of pain during the procedure on a visual analog scale. A rhinomanometric evaluation was conducted prior to and after the procedure. All patients were asked to evaluate the improvement of their symptoms. All patients' data and potential complications were put in a database and were statistically assessed. Results Statistical analysis showed significant improvement of their symptoms and of rhinomanometric results. No complications or side effects occurred. The mean operative time was 35 minutes. Conclusions Septal cartilage reshaping is an easy, painless, and bloodless method using an Erbium doped glass fiber Laser. Laser device LSC-701 (Arcuo Medical Inc.) is an effective, safe, and inexpensive medical equipment.

Facial resurfacing: An overview

Facial resurfacing is a broad topic referring to procedures that change the texture and appearance of skin. Resurfacing procedures are broadly classified as ablative or nonablative. Ablative procedures are considered the first line treatment for the most common indications for facial resurfacing, which are photoaging and acne scarring. The goal of this review is to provide an overview of the factors that optimize the clinical efficacy of an ablative procedure, including careful patient selection, preoperative skin preparation, correct operative technique, and vigilant postoperative care, as well as review both the traditional and some of the latest technologies that effectively resurface facial skin.

400-nm-Bandwidth Emission From a Cr-Doped Glass Fiber

Cr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> -doped glass fiber by a laser-heated pedestal growth method is reported. By analyzing the absorption spectra, the transitions of Cr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> and Cr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> in the fibers are identified. With appropriate pumping wavelength and divalent doping concentration, both Cr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> and Cr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> emission bands can be excited simultaneously, and become comparable in their fluorescent intensities. As a result, more than 400-nm-width emission peaked at 1144 nm was generated at room temperature. As much as 12muW of amplified spontaneous emission was obtained by pumping with a 900-nm Ti : sapphire laser

Dynamically Stable Super Gaussian Solitons in Semiconductor Doped Glass Fibers

In this paper we have investigated the propagation properties of chirped super Gaussian soliton pulses through semiconductor doped glass fibers which is a dispersive medium with cubic quintic nonlinearity. Using variational principle, the evolution equations of the soliton parameters such as amplitude, temporal width, position of centre, chirp etc. have been derived. The dynamics of these parameters have been analysed. Employing linear stability analysis we have shown that super Gaussian solitons are stable in semiconductor doped glass fibers.