Μm Er Research Articles

Assessment of optical and fluorescence aspects of Er3+-doped multicomponent B2O3 glasses as active media for 1.532 μm near-infrared optical amplifiers

Current work principally provides an idea on controlling the Er3+: NIR (near-infrared) emission characteristics by changing a glass constituent and finding a suitable glass host favorable to design a novel C-optical band (1.53–1.565 μm) amplifier. By melting and rapid quench route, six transparent Er3+ (1 mol%)-doped B2O3-rich glasses having different single and mixed alkali ions were fabricated, and optical and fluorescence (visible and NIR) traits including Er3+ ion upper-levels 4S3/2 and 4I13/2 decay dynamics were inspected for such samples. At 1.4–1.65 μm wavelength range, an intense and wide NIR luminescence band centered at 1.532 μm (Er3+: 4I13/2 → 4I15/2 transition) has been obtained by a 980 nm laser diode pumping (4I15/2 → 4I11/2). NIR fluorescence Δλeff (effective bandwidth) varied depending on added single or mixed alkali ions, and a maximum Δλeff ∼74.66 nm was acquired for Er3+: Li ions constituting glass. For the 4I13/2 → 4I15/2 transition, σemi (stimulated emission cross-section) was evaluated using both Füchtbauer–Ladenburg and McCumber's theories. In all glasses, comparably, higher gain bandwidth (= 5.384 × 10−26 cm3) and peak σemiM (= 1.692 × 10−20 cm2) values have been attained for 4I13/2 → 4I15/2 transition in Li ions containing sample, and also this glass possesses the largest σabs (absorption cross-section) (= 1.459 × 10−20 cm2) for 4I15/2 → 4I13/2 transition. Further, at distinctive P (population inversion) values, gain spectra were computed, and all samples show C-optical band amplification beginning from P = 50%. All analyzed NIR fluorescence results indicate that Li ions having glass could be a potential gain medium for fiber amplifiers.

Power-scalable two-wavelength pumped Er:YAP laser at 2.9 [formula omitted

A method of scaling the output power of a 3 μm Er-doped solid-state laser with two pump wavelengths at 976 nm and 1.7 μm is proposed. Compared with the typical scheme with a single 976 nm pump wavelength, the second 1.7 μm pump wavelength promotes the excited-state absorption and thus increases the effective pump rate and quantum efficiency. A proof-of-principle experiment has been conducted in a 2.9 μm Er:YAP laser with two pump sources, showing a power improvement of 227% at the threshold and 5.8% at 9.3 W of 976 nm absorbed pump power.

Red-diode-clad-pumped CW and mode-locked Er:ZBLAN fiber laser at 3.5 µm.

We report on a red-diode-clad-pumped continuous-wave (CW) and mode-locked Er:ZBLAN fiber laser at 3.5 µm for the first time. Numerical simulation shows that a heavily-doped Er:ZBLAN fiber is favorable for effective generation of 3.5 µm laser through 658 nm laser diode pumping. Using a 7.0 mol.% Er:ZBLAN fiber, CW output power of 203 mW was experimentally obtained at 3462 nm. By incorporating a home-made semiconductor saturable absorber mirror into the cavity, diode-pumped CW mode-locked 3.5 µm Er:ZBLAN fiber laser was first demonstrated with an average power of 19 mW, a pulse duration of 18.1 ps, and a repetition rate of 46 MHz. The research results show that red-diode-clad-pumping provides a simple and potential scheme for 3.5 µm CW and mode-locked Er:ZBLAN fiber laser.

Pr3+/Tm3+/Er3+ tri-doped tellurite glass with ultra-broadband luminescence in the optical communication band

Pr3+/Tm3+/Er3+ tri-doped tellurite glass was synthesised using a melt-quenching method, and the broadband luminescent properties were measured in the near-infrared band. With an optimal combination of the three ions, a broadband luminescence ranging from 1280 to 1630 nm, located within the optical communication window of silica transmission fibre, was acquired under 808 nm excitation. The broadband luminescence comprises three bands: 1.34 μm (Pr3+), 1.47 μm (Tm3+), and 1.53 μm (Er3+); and the full width at half-maximum was about 248 nm. This valuable result is of great significance for novel broadband fibre amplifiers and ultra-short pulsed lasers.

High-power 1640 nm Er:Y2O3 ceramic laser at room temperature.

We report on the high-power operation of an Er:Y2O3 ceramic laser at approximately 1.6 µm using a low-scattering-loss, 0.25 at. % Er3+-doped ceramic sample fabricated in-house via a co-precipitation process. The laser is in-band pumped by an Er, Yb fiber laser at 1535.6 nm and generates 10.2 W of continuous-wave (CW) output power at 1640.4 nm with a slope efficiency of 25% with respect to the absorbed pump power. To the best of our knowledge, this is the first demonstration of an approximately 1.6 µm Er:Y2O3 laser at room temperature. The prospects for further scaling of the output power and lasing efficiency via low Er3+ doping and reduced energy-transfer upconversion are discussed.

Broadband luminescence at 1.5 μm of Er P co-doped high silica glass by nanoporous doping technology

The Er P co-doped high silica glass is made by sintering nanoporous silica glass (NPSG) at 1150 °C. Under 980 nm laser excitation, a broadband luminescence at 1.5 μm is obtained, which has multiple luminescence peaks. In order to analyze the luminescence broadening, we fitted the luminescence peaks and observe the change laws of the center wavelength, area integral and FWHM of each fitting peak. The study found that with the change of Er P concentration, the luminescence broadened to the S-band, and the center wavelength, integral area and FWHM of their fitting peaks near 1512 nm, 1540 nm, and 1593 nm change regularly. The change of Er P concentration leads to the change of these fitting peaks, which makes the luminescence broaden.

Manipulation of Molecular Vibrations on Condensing Er3+ State Densities for 1.5 μm Application.

Vibrational modes of chemical bonds in organic erbium (Er3+) materials play an important role in determining the efficiency of the 1.5 μm Er3+ emission. This work studies the energy coupling of the Er3+ intra-4f transitions and vibrational modes. The results demonstrate that the coupling introduces enormous nonradiative internal relaxation, which condenses the excited erbium population on to the 4I13/2 state. This suggests that vibrational modes can be advantageous for optimizing the branching ratio for the 1.5 μm transition in organic erbium materials. Through control of the quenching effect on to the 4I13/2 state and a reliable determination of intrinsic radiative rates, it is found that the pump power for population inversion can be reduced by an order of magnitude at high erbium concentrations compared to conventional inorganic erbium materials.

Spectroscopy and efficient laser operation around 2.8 μm of Er:(Lu,Sc)2O3 sesquioxide ceramics

A transparent “mixed” 7 at.% Er:(Lu,Sc)2O3 sesquioxide ceramic was fabricated by hot isostatic pressing of commercial sesquioxide powders at 1750 °C/200 MPa in argon atmosphere. It exhibited a cubic bixbyite-type structure (a = 10.198 Å), a mean grain size of 5.7 μm and high low-signal transmission of 79.1 % in the near-IR. The spectroscopic properties of Er3+ ions were studied. For the 4I11/2 → 4I13/2 transition, the stimulated-emission cross-section σSE is 1.30 × 10−20 cm2 at 2719 nm, the corresponding luminescence branching ratio B(JJ’) is 19.9 % and the radiative lifetime of the 4I11/2 state is 4.80 ms, as determined using a Judd-Ofelt theory accounting for intermediate configuration interaction. The crystal-field splitting of Er3+ multiplets was studied at 12 K. The ceramic exhibits a significant inhomogeneous broadening of spectral bands. An Er:(Lu,Sc)2O3 ceramic laser generated 342 mW at 2.71 and 2.85 μm with a high slope efficiency of 41.7 % (exceeding the Stokes limit) and a laser threshold of 125 mW.

Compact diode-pumped CW and Q-switched 2.8 µm Er:YLF laser

This paper presents a compact diode-pumped continuous-wave Er:YLF laser emitting radiation at 2.8 µm with output power 2.9 W and slope efficiency 26.2%. Moreover, the Q -switching regime was successfully tested with a Fe:ZnSe polycrystal used as a modulator. Passive Q -switching results in the shortest pulse duration of 21 ns with repetition rate 50 kHz and peak power 252 W.

20-hydroxyecdysone dilates muscle arterioles in a nitric oxide-dependent, estrogen ER-β receptor-independent manner

Background20-hydroxyecdysone is an ecdysteroid which is abundant in plants and insects and has anabolic potentials in mammals. It was recently shown to have affinity for estrogen ER-β receptor, which could potentially make it vasodilatory. Yet this possibility has not been previously investigated. Such an activity in muscle arterioles could have huge implications for muscle blood flow and performance. Hypothesis/PurposeWe hypothesized that 20-hydroxyecdysone would dilate muscle arterioles by activating estrogen ER-β receptors. To test this, we investigated its vasodilatory properties in ovine muscle arterioles and further explored the mechanisms in human tissues and cells. Study DesignThe study was carried out experimentally, employing functional recording of arteriolar reactivity in intact ovine muscle arterioles and gene and protein expression analysis in human tissues and cells. MethodsDirect effects of the compound on arteriolar tone were assessed by wire myography in abdominal muscle and mesenteric arterioles isolated from samples obtained from male sheep. The roles of endothelial nitric oxide synthase (NOS3), cyclooxygenase (COX) and estrogen ER-β receptor (ER-β), and their effects were determined with specific blockers. The NOS3 mRNA and protein expressions were analyzed in human coronary artery endothelial cells (HCAECs) and humanized liver of uPA+/+-SCID mice, before and after 20-hydroxyecdysone administration. ResultsComparable dose-dependent relaxations were recorded for 20-hydroxyecdysone in both muscle and mesenteric arterioles with maximum relaxations of 46.94 ± 5.84% and 56.88 ± 7.04% respectively, which were not statistically different. Similar relaxation was recorded for β-estradiol in both arterioles. NOS inhibition with 100 µM L-NAME attenuated the relaxation to 20-hydroxyecdysone (p < 0.001) and β-estradiol (p < 0.001) in muscle arterioles. Neither COX inhibition with 10 µM indomethacin nor ER blockade with 1 µM PHTPP or 1 µM ICI182780 had any noticeable effect on 20-hydroxyecdysone relaxation in these arterioles. Transcriptome analysis revealed elevated NOS3 gene in the humanized liver of 20-hydroxyecdysone-treated mice, and, elevation of both NOS3 mRNA and protein in HCAECs treated with 20-hydroxyecdysone. ConclusionThe data suggest that 20-hydroxyecdysone has a nitric oxide-dependent, but ERβ-independent, vasodilatory property in muscle arterioles. The benefits to muscle blood flow would however be dependent on the impact of its effects on other vascular beds.

Effect of 9.3 μm CO2 and 2.94 μm Er:YAG Laser vs. Bur Preparations on Marginal Adaptation in Enamel and Dentin of Mixed Class V Cavities Restored With Different Restorative Systems

This study aimed to compare marginal adaptation in enamel and dentin before and after aging of laser vs. bur-prepared mixed class V cavities restored by different restorative systems. Seventy two caries-free human molars were distributed to nine experimental groups; cavities were prepared using two different lasers: a handpiece -integrated 2.94 μm Er:YAG laser at 4.5 W, 300 mJ, and 0.75 W, 50 mJ with 15 Hz (LiteTouch, Light Instruments, Israel) and a novel CO2 laser at 12.95 W, 19.3 mJ, and 4.1 W, 6.11 mJ with 671 Hz (Solea 9.3 μm, Convergent Dental, USA). Cavities prepared with conventional diamond burs (Intensiv, Switzerland) in a red contra angle at high speed under maximal water cooling served as control. Cavities were prepared under simulation of dentinal fluid and restored using three different self-etching universal adhesives in combination with three nanohybrid composites, applied in two layers: Scotchbond Universal with Filtek Supreme XTE (3M, USA), G-Premio BOND with Essentia Universal (GC, Japan), and OptiBond Universal with Harmonize Universal (Kerr, USA). After restorations' polishing and simultaneous thermal (5–50°C, 2 min each) and mechanical loading (max. 49 N; 200,000 cycles), replicas of restoration margins were examined under SEM at × 200 magnification. Percentages of continuous margins (CMs) were quantified before and after the fatigue test and statistically compared (two-way ANOVA with Fisher's least significant difference [LSD] post hoc test). Significant differences were found in almost all groups between the results before and after the fatigue test, as well as between the different preparation tools and restorative materials (p &amp;lt; 0.05). Traditional bur preparations are confirmed as gold standard in enamel and dentin, as all three tested restorative systems provide results of marginal adaptation of more than 80% CM after loading. Er:YAG laser preparations can be equally effective in combination with SBU/Filtek Supreme XTE. CO2 laser ablation could not provide convincing results with the tested self-etching restorative systems. Marginal adaptation has been highly dependent on the substrate and showed impaired adhesion, especially in enamel. Scotchbond Universal/Filtek Supreme XTE showed the highest and most stable values of CM. The other two restorative systems were highly dependent on the preparation device of the substrate.

200 µJ, 13 ns Er:ZBLAN mid-infrared fiber laser actively Q-switched by an electro-optic modulator.

We report, as far as we know for the first time, on a pulsed 2.7 µm Er:ZBLAN fiber laser Q-switched by an electro-optic modulator. The Q-switched operation was achieved with a repetition rate range of 100 Hz-50 kHz. Pulse energy of 205.7 µJ and pulse width down to 13.1 ns, yielding a peak power of 15.7 kW, were obtained at a repetition rate of 100 Hz. The linewidth of the output spectrum was as narrow as 0.4 nm. The pulse width and the pulse peak power, to the best of our knowledge, are currently the shortest and the highest in the 3-µm-band Q-switched fiber lasers, respectively.

Laser potential of Pr3+ doped chalcogenide glass in 5-6 μm spectral range

Cross-relaxation processes in Pr3+ doped selenide glass provided efficient population of the lowest excited state 3H5 of Pr3+ ions under pulsed pumping by 1.54 µm Er:glass laser. Stimulated emission at 5.5-5.9 µm corresponding to 3H5→3H4 transition of Pr3+ ions was observed in vitreous matrix for the first time.

High energy (0.8 J) mechanically Q-switched 2.94 μm Er:YAG laser.

We report a flashlamp pumped mechanically Q-switched (MQS) 2.94 μm Er:YAG laser based on a spinning mirror with a highest output energy of 805 mJ at a pulse duration of 61 ns and 13 MW of peak power at 1 Hz repetition rate. This record output energy was achieved with the use of 300 mm long MQS Er:YAG laser cavity consisting of a 70% output coupler, 7 × 120 mm AR coated Er(50%):YAG crystal, and 4200 rad/s angular speed of the spinning mirror. The pulse jitter was also measured by using optical triggering and was smaller than 10 ns for 150 ns Q-switched pulses, which could be applicable to many laser applications where precise synchronization of pulses is required.

LD-pumped 2.8 μm Er:Lu2O3 ceramic laser with 6.7 W output power and >30% slope efficiency

We present a high-power, high-efficiency, laser-diode-pumped 2.8 μm Er:Lu2O3 ceramic laser generating record power at room temperature. Careful thermal management and pump-radius enlargement resulted in a continuous-wave output power of 6.7 W at 2845 nm, with a 30.2% slope efficiency. To our knowledge, this is the highest output power and slope efficiency ever achieved from a laser-diode-pumped 3 μm Er-doped ceramic laser. These results confirm the possibility of generating high-output-power, high-efficiency laser using transparent ceramics.

Optical chopper based mechanically Q-switched ∼3 μm Er:YAP single-crystal laser

We developed a compact and low-cost diode-pumped ∼3 μm mechanically Q-switched Er:YAP laser with high-power using an optical chopper. At 2.4 W pumping and 7 kHz modulation frequency, a stable single-pulse repetitively Q-switched laser with a wavelength of 2.796 μm has been observed. We recorded the pulse duration, the peak power, and the pulse energy of 264 ns, 22 W, and 5.9 μJ, respectively. As increasing pumping power to 7.4 W at a frequency of 10 kHz, the lasing wavelength shifted to 2.921 μm and a stable multiple-pulse laser was observed. The pulse with 75 ns duration and 34 μJ energy has been observed, corresponding to a peak power of 456 W. The peak power and the pulse energy are the highest value ever reported for an actively Q-switched mid-infrared (IR) Er:YAP laser. Thus, this laser has the potential to be utilized for industrial and science fields as high-power mid-IR light source.

Nanowired structure, optical properties and conduction band offset of RF magnetron-deposited n-Si\\In2O3:Er films.

RF magnetron-deposited Si\\In2O3:Er films have the structure of the single-crystalline bixbyite bcc In2O3 nanowires bunched into the columns extended across the films. The obtained films have a typical In2O3 optical band gap of 3.55 eV and demonstrate the 1.54 μm Er3+ room temperature photoluminescence. The current across the film flows inside the columns through the nanowires. The current through the MOS-structure with the intermediate low barrier In2O3:Er dielectric was investigated by the thermionic emission approach, with respect to the partial voltage drop in silicon. Schottky plots ln(I/T 2 ) versus 1/kT of forward currents at small biases and backward currents in saturation give the electron forward n-Si\\In2O3:Er barrier equal to 0.14 eV and the backward In\\In2O3:Er barrier equal to 0.21 eV.

Mechanical properties of glass-fibre-reinforced composite posts after laser irradiation with different energy densities.

The aim of the present study was to evaluate the effect of the surface treatments on flexural strengths and flexural modulus of glass-fibre-reinforced composite (GFRC) posts. Sixty-three posts were randomly divided into 9 groups (n=7), and various surface treatments were performed. The control group was left untreated. Other groups were treated with 9% hydrofluoric acid, sandblasting with 120µm Al2 O3 particles and Er,Cr:YSGG laser irradiation with different powers (1W, 2W, 3W, 4W, 5W and 6W). The samples were subjected to 3-point bending test, and data were calculated. Statistical analysis was performed. The flexural strengths of fibre posts treated with sandblasting, hydrofluoric acid, 1W and 2W laser were statistically similar with control group (P>0.01). However, the flexural strength of fibre posts treated with 3W, 4W, 5W and 6W laser was statistically lower than control group (P<0.01). High laser irradiations cause melting on the post surface and breaks in fibrils.

First demonstration of ~ 5 µm laser action in terbium-doped selenide glass

4.9–5.5 µm laser oscillations were observed in high-purity bulk terbium-doped Ge36Ga5Se59 glass pumped by pulsed 2.93 µm Er:YAG laser. This is the first evidence of laser action corresponding to 7F5–7F6 transition of Tb3+ ions and of mid-infrared lasing in chalcogenide glass host.

Near infrared broadband and visible upconversion emissions of erbium ions in oxyfluoride glasses for optical amplifier applications

Optical and visible upconversion properties of erbium (Er3+)-doped oxyfluoro-titania-phosphate glasses (PCfBfTiEr) with the chemical composition of P2O5–CaF2–BaF2–TiO2–Er2O3 have been explored. An intense emission at 1.53 µm of Er3+-doped PCfBfTiEr1.0 glass was obtained upon excitation of 980 nm diode laser. In addition, green and red visible upconversion emissions were obtained upon the optical excitation of Er3+ ions doped PCfBfTiEr glasses at 980 nm diode laser. Upconversion emission intensities and population densities of respective levels were tuned with the variation of Er3+ ion concentration. Fluorescence decay curves of the 4I13/2 level of PCfBfTiEr glasses were obtained upon 980 nm laser excitation in the pulsed mode and revealed a mono-exponential behavior. The stimulated emission cross-section (σem), full width at half maximum (FWHM) and gain bandwidth product (σem × FWHM) were found to be 9.3 × 10−21 cm2, 95.61 nm and 889.2 cm−2 nm for PCfBfTiEr2.0 glass, respectively. These results recommend that the Er3+ ions doped PCfBfTiEr glasses may possibly be worthy for the laser and optical amplification applications at 1.53 µm.