Μm Optical Amplifiers Research Articles

Er3+ -doped oxyfluoroborosilicate glass ceramics with embedded CaF2 nanoparticles for 1.53 μm broad band applications

The CaF2 based oxyfluoroborosilicate glasses and glass ceramics doped with Er3+ ions were prepared via melt quench process followed by heat treatment and characterized for 1.53 μm broadband applications. The optimized glass ceramic sample was obtained at 450oC/1h heat treatment. The Er3+ concentration was optimized as 1.0 mol% for efficient emission at 460 nm excitation through concentration dependent luminescence analysis. The spectroscopic parameters such as Ωλ=2,4,6 parameters and the radiative parameters such as spontaneous transition probability rates (AR), branching ratios (βR) and decay times (τR) were calculated applying the standard Judd-Ofelt theory. The effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe×Δλeff), quantum efficiency (η) and figure of merit (σe×τR) were calculated as 25.78 nm, 13.42×10-21 cm2, 3.46×10-26 cm3, 82.83% and 5.32×10-23 cm2s, respectively for the optimized glass ceramic sample. The exchange type of energy transfer among the excited Er3+ ions results the quenching in luminescence and the non-exponentiality in decay curves. The systematic investigations carried out indicate that the glass ceramic obtained at 450oC/1h heat treatment was proficient for 1.53 μm broadband fiber lasers and optical amplifiers in S and C band communication window.

Spectral and infrared luminescent characteristics of 40PbO–35Bi2O3–25Ga2O3 glasses doped with Er3+

The heavy metal oxide glasses based on 40PbO–35Bi2O3–25Ga2O3 composition doped with different Er3+ ions content were synthesized in corundum crucible. The concentration dependences of band gap energy and Urbach energy in a series of glass samples were analyzed. The studied matrix showed wider IR transparency region comparing with other heavy metal oxide glasses containing PbO: up to 6.5 μm. The content of hydroxyl impurities NOH was evaluated based on infrared transmission spectra. The comparison of obtained NOH values with other oxide glasses indicate that studied composition has a moderate hydroxyl groups content. Luminescence properties of 4I13/2 → 4I15/2 transition were measured under 980 nm wavelength excitation. The correlation of radiative characteristics with NOH content was determined. The maximum relative luminescence intensity had the sample doped with 0.869 × 1020 ion/cm3 of Er3+. Comparative analysis of FWHM, peak value of emission cross-section, and radiative lifetime of 4I13/2 → 4I15/2 transition with other glass matrixes indicates the prospects of the investigated composition as advanced material for 1.5 μm optical amplifiers.

Effect of Bi2O3 on JO parameters and spectroscopic properties of Er3+ incorporated sodiumfluoroborate glasses for amplifier applications

This work delivers effect of bismuth on the luminescence and gain characteristics of Er3+ ions incorporated sodiumfluoroborate glasses prepared through melt quenching method. Employing the absorption spectral measurements, Judd–Ofelt intensity parameters (Ω2,Ω4,Ω6) were determined and are used to compute various luminescence radiative properties. From visible emission profile studies, stimulated emission cross-section, CIE color coordinate and Color Correlated Temperature values pertaining to the titled glasses are evaluated. Using Mc-Cumber theory, absorption cross-section (σa), emission cross-section (σe), gain coefficient values for NIR 4I13/2→4I15/2 transition are evaluated and compared with other reported glasses. Of all the present glasses, 40BiBNCE glass exhibit higher σa (66.49 × 10–22 cm2), σe (75.95 × 10–22 cm2) and optimum value of figure of merit (402.54 × 10−28 cm3). Based on the visible and NIR luminescence features, 40BiBNCE glass can be suggested as a potential candidate for the fabrication of solid state lasers, gain medium for 1.53 µm optical amplifier applications.

Influence of Er3+ ions on structural and fluorescence properties of SiO2-B2O3- Na2Co3-NaF-CaF2 glasses for broadband 1.53 μm optical amplifier applications

The oxyfluoroborosilicate (SiO2-B2O3- Na2Co3-NaF-CaF2) glasses activated with varied concentrations of trivalent Erbium ions have been prepared by using conventional melt quenching method. The structural, optical and luminescence properties were examined with X-ray diffraction, X-ray Photoelectron, Fourier Transform Infrared, Optical absorption, fluorescence emission spectra and lifetime decay analysis. From the absorption spectra of the prepared glasses, oscillatory strength of each band was calculated and evaluated the bonding parameters (β, δ) values. Judd-Ofelt theory had been used to determine the spectral intensity parameters (Ωλ = 2,4 and 6) and some important radiative parameters like total radiative transition probability (AT), radiative lifetime (τR) and radiative branching ratios were also calculated for 4I15/2 → 4I13/2 transition. Optical band gap energy (Eopt) estimated/determined for direct and indirect allowed transitions. From the NIR emission spectra, 0.5 mol% Erbium ions activated glass possesses maximum intensity for 4I13/2 → 4I15/2 transition and evaluated the stimulated emission cross-section (σemi) (9.47 × 10−21 cm2), Gain bandwidth parameter (σemi x ∆λeff) (0.823 × 10−25 cm3) and gain per unit length (σemi x τmes) (51.65 × 10−25 cm2s) for this prepared glass and compared with other reported glasses. Using Mc Cumber theory, σemi was calculated for 4I13/2 → 4I15/2 transition from the absorption spectrum of 0.5 mol% Er3+ ions doped glass. The lifetime (τm) of 4I13/2 level was decreased from 6.94, 6.61, 5346, 5.44 and 2.74 ms with the increase in Erbium ions concentrations from 0.05, 0.1, 0.5, 1.0 and 2.0 mol% respectively. This decrease may be due to concentration quenching effect. The high values of (σemi) (9.47 x 10−21 cm2), (σemi x ∆λeff) (0.823 × 10−25 cm3) and τm (5.45 ms) for 0.5 mol% of Er3+ ions activated oxyfluoroborosilicate glass suggesting that the glasses could be used as potential candidate for 1.53 μm optical amplifier applications.

国外差分吸收激光雷达探测大气CO 2 研究综述

Differential absorption lidar is an indispensable tool to measure atmospheric CO2 for temporal and spatial distribution. The 2.0 μm wavelength Ho:Tm:YLF/Ho:Tm:LuLiF lidar were used for remote sensing atmospheric CO2 with heterodyne receiver. The KTP parametric oscillator was injected into the seeds, and a differential absorption lidar (DIAL) system of 1.6 μm by using the photon counting technique to profile the atmospheric CO2 in the troposphere under 7 km. Modulation continuous wave seed laser intensity and the integral path differential absorption lidar, common 1.6 μm optical fiber amplifier, and the use of correlation detection technique, have unique advantages and characteristics in the detection of atmospheric CO2 column concentrations. The space program for detecting atmospheric CO2 column concentrations is NASA's ASENDS (active sensing of CO2 emission over nights, days, and seasons) mission which adopts the method of pulse and integral path differential absorption. The absorption of CO2 gas cell as a reference to stabilize seed light frequency and the precise control of cavity length lock the on-line wavelength of transmitter, is the key technique for DIAL to measure atmospheric CO2.

100 kHz Yb-fiber laser pumped 3 μm optical parametric amplifier for probing solid-state systems in the strong field regime.

We report on a laser source operating at 100 kHz repetition rate and delivering 8 μJ few-cycle mid-IR pulses at 3 μm. The system is based on optical parametric amplification pumped by a high repetition rate Yb-doped femtosecond fiber-chirped amplifier. This high-intensity ultrafast system is a promising tool for strong-field experiments (up to 50 GV/m and 186 T) in low ionization potential atomic and molecular systems, or solid-state physics with coincidence measurements. As a proof of principle, up to the sixth harmonic has been generated in a 1 mm zinc selenide sample.

Effect of silver nanoparticles on spectroscopic properties of Er3+ doped phosphate glass

The Er3+ doped zinc phosphate glasses containing Ag nanoparticles (Ag NPS) were synthesized from high purity raw materials by melt quenching method. The transmission electron microscopic (TEM) images confirm the presence of spherical silver NPs having average diameter in the range of 20–40nm. A wide absorption band peaking at about 403nm was observed due to surface plasmon resonance (SPR) of Ag NPs. The Judd–Ofelt (JO) parameters Ω2, Ω4 and Ω6, were determined for Er3+ ions using the absorption bands. The quality factor was determined and is found to be in the same order (0.52–1.12) than other host glasses. The enhanced photoluminescence (PL) intensity with Ag adding was attributed to the increased local field on the Er3+ ions located in the proximity of the NPs and/or the energy transfer from the metallic Ag NPs to the Er3+ ions. The absorption and emission cross-sections are calculated and determined for the 4I13/2→4I15/2 transition and then compared with other reported doped glasses. The phosphate glasses are promising gain media for developing the solid-state 1.53μm optical amplifiers.

Parametric generation of energetic short mid-infrared pulses for dielectric laser acceleration

Laser-driven high-gradient electron acceleration in dielectric photonic structures is an enabling technology for compact and robust sources of tunable monochromatic x-rays. Such advanced x-ray sources are sought in medical imaging, security, industrial, and scientific applications. The use of long-wavelength pulses can mitigate the problem of laser-induced breakdown in dielectric structures at high optical intensities, relax the structure fabrication requirements, and allow greater pulse energy to be injected into the structure. We report on the design and construction of a simple and robust, short-pulse parametric source operating at a center wavelength 5 μm, to be used as a pump for a dielectric photonic structure for laser-driven acceleration. The source is based on a two-stage parametric downconversion design, consisting of a β-BaB2O4-based 2.05 μm optical parametric amplifier (OPA) and a ZnGeP2-based 5 μm OPA. The 2.05 μm OPA is presently pumped by a standard Ti:sapphire chirped-pulse amplified laser, which will be replaced with direct laser pumping at wavelengths in the future. The design and performance of the constructed short-pulse mid-infrared source are described. The demonstrated architecture is also of interest for use in other applications, such as high harmonic generation and attosecond pulse production.

Bidirectional Energy Transfer in Bi‐Tm‐Codoped Glasses

In this manuscript, we report an ultrabroadband luminescence covering the whole 1000–1800 nm in singly doping glass, and a superbroadband emission from 1000 to 2000 nm in ‐Tm3+‐codoped glasses excited at 808, 980 nm, respectively. We also confirm a bidirectional energy transfer mechanism between and Tm3+. Broadband luminescence is used to realize 1–2 μm optical amplifier and tunable laser. Luminescent properties of glasses are investigated systematically. Peak position and intensity of the near‐infrared emission depend strongly on excitation wavelength. Based on a collaborative investigation of the photoluminescence and luminescence decay, a plausible bidirectional energy transfer mechanism between and Tm3+ is confirmed.

Er–Yb codoped phosphate glasses with improved gain characteristics for an efficient 1.55 µm broadband optical amplifiers

We have investigated the optical properties of phosphate glasses codoped with Er3+–Yb3+ as a function of Yb3+concentration in order to evaluate their potential as both glass laser systems and amplifier materials. The results of differential scanning calorimetry (DSC) measurements indicate a good thermal stability of phosphate glasses. The Judd–Ofelt (JO) model has been applied to absorption intensities of Er3+ (4f11) transitions to establish the so-called Judd–Ofelt intensity parameters: Ω2, Ω4,Ω6. With the weak spectroscopic quality factors Ω4/Ω6 (0.38), we expect a relatively prominent Infrared laser emission. The intensity parameters are used to determine the spontaneous emission probabilities of some relevant transitions, the branching ratio and the radiative lifetimes of several excited states of Er3+ and compared to the equivalent parameters for other host glasses.Both the IR photoluminescence (PL) intensity and the PL decay time were found to largely increase with Yb3+concentration and the maximum quantum efficiency for the 1.55µm emission was found to be in the order of 91%. We show that the Yb3+ acts as sensitizer for Er3+ and contributes largely to the improvement of the spectroscopic properties of phosphate glasses codoped with Er3+–Yb3+.Using McCumber method, absorption cross-section and calculated emission cross-section, for the 4I13/2→ 4I15/2 transition, were determined and compared for the doped and codoped glasses. The phosphate glasses are promising gain media for developing the solid-state 1.55µm optical amplifiers.

Gain properties of the transition emissions near the second telecommunication window in Ho 3+-doped multicomponent heavy-metal gallate glasses

Efficient infrared emissions near the second telecommunication window in Ho 3+-doped multicomponent heavy-metal gallate (MHG) glasses have been observed. The maximum stimulated emission cross-sections are calculated to be 2.94×10 −21 and 2.08×10 −21 cm 2 for 1200 and 1390 nm emissions, respectively. Excitation spectra reveal that the 642 and 538 nm wavelengths are practical pumping conditions for 1.2 and 1.39 μm emissions, respectively. Gain cross-sections are evaluated and positive gain bands have been anticipated. The theoretical gain results indicate that the appealing infrared emissions near the second telecommunication window from Ho 3 + -doped MHG glasses with low maximum phonon energy of ∼660 cm −1 make them attractive in developing ∼1.2 μm and E-band (1360–1460 nm) optical amplifiers.

Energy transfer and enhanced 154 μm emission in Erbium-Ytterbium disilicate thin films

α-(Yb1-xErx)2Si2O7 thin films on Si substrates were synthesized by magnetron co-sputtering. The optical emission from Er3+ ions has been extensively investigated, evidencing the very efficient role of Yb-Er coupling. The energy-transfer coefficient was evaluated for an extended range of Er content (between 0.2 and 16.5 at.%) reaching a maximum value of 2 × 10⁻¹⁶ cm⁻³s⁻¹. The highest photoluminescence emission at 1535 nm is obtained as a result of the best compromise between the number of Yb donors (16.4 at.%) and Er acceptors (1.6 at.%), for which a high population of the first excited state is reached. These results are very promising for the realization of 1.54 μm optical amplifiers on a Si platform.

Yb 3+ effect on the spectroscopic properties of Er–Yb codoped SnO 2 thin films

We have investigated the optical properties of sol–gel thin films of tin dioxide (SnO 2) codoped with Er 3+–Yb 3+ as a function of Yb 3+ concentration. The Judd–Ofelt model has been applied to absorption intensities of Er 3+ (4f 11) transitions to establish the so-called Judd–Ofelt intensity parameters: Ω 2, Ω 4, Ω 6. Various spectroscopic parameters were obtained to evaluate their dependence and the potential of the samples as a laser material in the eye-safe laser wavelength (1.53 μm) as a function of Yb 3+ concentration. An amelioration of the quality factor Ω 4/ Ω 6 was found with Yb content. Both the IR photoluminescence (PL) intensity and the up-conversion emission, from Er 3+ ion in SnO 2, were found to increase with Yb concentration. We show that the Yb 3+ ion acts as sensitizer for Er 3+ ion and contributes largely to the improvement of the spectroscopic properties of SnO 2:Er. The mechanism of up-conversion emission is discussed and a model is proposed. The results showed that sol–gel SnO 2 is promising gain media for developing the solid-state 1.5 μm optical amplifiers and tunable up-conversion lasers.

Upconversion and infrared luminescences in Er 3+/Yb 3+ codoped Y 2O 3 and (Y 0.9La 0.1) 2O 3 transparent ceramics

Er 3+ and Yb 3+ codoped Y 2O 3 and (Y 0.9La 0.1) 2O 3 transparent ceramics were fabricated by the conventional ceramics processing with nanopowders. Compared to Er/Yb:Y 2O 3, Er/Yb:(Y 0.9La 0.1) 2O 3 ceramics had higher transmittance. Intense upconversion (UC) and infrared emission (1543 nm) were observed under excitation of 980 nm. According to three intensity parameters Ω 2, Ω 4, and Ω 6 fitted by the Judd–Ofelt theory, the spectroscopic quality parameters ( X), radiative lifetimes ( τ rad), and emission cross-sections ( α em) were determined. Er/Yb:(Y 0.9La 0.1) 2O 3 ceramics owned broader peaks and longer lifetime (12.3 ms) at 1548 nm due to the glass-like structure of (Y 0.9La 0.1) 2O 3 ceramics. The results showed Y 2O 3 and Y 1.8La 0.2O 3 transparent ceramics are promising gain media for developing the solid-state 1.5 μm optical amplifiers and tunable UC lasers.

Optical properties and local structure of Dy 3+-doped chalcogenide and chalcohalide glasses

Dy 3+-doped Ge-Ga-Se chalcogenide glasses and GeSe 2-Ga 2Se 3-CsI chalcohalide glasses were prepared. The absorption, emission properties, and local structure of the glasses were investigated. When excited at 808 nm diode laser, intense 1.32 and 1.55 μm near-infrared luminescence were observed with full width at half maximum (FWHM) of about 90 and 50 nm, respectively. The lifetime of the 1.32 μm emission varied due to changes in the local structure surrounding Dy 3+ ions. The longest lifetime was over 2.5 ms, and the value was significantly higher than that in other Dy 3+-doped glasses. Some other spectroscopic parameters were calculated by using Judd-Ofelt theory. Meanwhile, Ge-Ga-Se and GeSe 2-Ga 2Se 3-CsI glasses showed good infrared transmittance. As a result, Dy 3+-doped Ge-Ga-Se and GeSe 2-Ga 2Se 3-CsI glasses were believed to be useful hosts for 1.3 μm optical fiber amplifier.

Intense upconversion and infrared emissions in Er3+–Yb3+ codoped Lu2SiO5 and (Lu0.5Gd0.5)2SiO5 crystals

High optical quality Lu2SiO5 (LSO) and (Lu0.5Gd0.5)2SiO5 (LGSO) laser crystals codoped with Er3+ and Yb3+ have been fabricated by the Czochralski method. Intense upconversion (UC) and infrared emission (1543nm) are observed under excitation of 975nm. The luminescence processes are explained and the emission efficiencies are quantitatively obtained by measuring the UC efficiency and calculating the emission cross section. The temperature-dependent optical properties of the crystals are also investigated. Our study indicates that Er3+–Yb3+:LSO and Er3+–Yb3+:LGSO crystals are promising gain media for developing the solid-state 1.5μm optical amplifiers and tunable UC lasers.

Effect of Bi 2O 3 on spectroscopic properties and energy transfer in Yb 3+–Er 3+-co-doped bismuth borate glasses for 1.5 μm optical amplifiers

In this paper, the effect of Bi 2O 3 on the optical absorption and emission, energy transfer, and gain property of Yb 3+–Er 3+-co-doped bismuth borate glasses has been investigated. An increase of the emission cross-section and fluorescence lifetime of Er 3+ ions around 1.5 μm with Bi 2O 3 content was shown. The increase of Bi 2O 3 content is also beneficial to obtaining a large absorption cross-section at 980 nm and increasing the energy transfer from Yb 3+ to Er 3+. Furthermore, in the 45Bi 2O 3–55B 2O 3 glass, gain curve is almost flat in the range from 1.53 to 1.60 μm. The results indicate that the Yb 3+–Er 3+-co-doped bismuth borate glasses have good prospect as a candidate of gain medium for 1.5 μm broadband amplifier.

Thermal stability and spectroscopic properties of Er 3+-doped antimony-borosilicate glasses

This paper reports on the optical spectroscopic properties and thermal stability of Er 3+-doped antimony-borosilicate glasses for developing 1.5 μm optical amplifiers. Upon excitation at 980 nm laser diode, an intense 1.5 μm infrared fluorescence has been observed with the maximum full width at half maximum (FWHM) of 90 nm for Er 3+-doped antimony-borosilicate glasses. The emission cross-section and the lifetime of the 4 I 13/2 level of Er 3+ ions are 6.3 × 10 −21 cm 2 and 0.30 ms, respectively. It is noted that the product of the emission cross-section and FWHM of the glass studied is as great as 567 × 10 −21 cm 2 nm, which is comparable or higher than that of bismuthate and tellurite glasses.

(GaIn)(NAsSb): MBE GROWTH, HETEROSTRUCTURE AND NANOPHOTONIC DEVICES

Dilute nitride GaInNAs and GaInNAsSb alloys grown on GaAs have quickly become excellent candidates for a variety of lower cost 1.2–1.6 μm lasers, optical amplifiers, and high power Raman pump lasers that will be required in the networks to provide high speed communications to the desktop. Because these quantum well active regions can be grown on GaAs , the distributed mirror technology for vertical cavity surface emitting lasers coupling into waveguides and fibers and photonic crystal structures can be readily combined with GaInNAsSb active regions to produce a variety of advanced photonic devices that will be crucial for advanced photonic integrated circuits. GaInNAs ( Sb ) provides several new challenges compared to earlier III–V alloys because of the limited solubility of N , phase segregation, nonradiative defects caused by the low growth temperature, and ion damage from the N plasma source. This paper describes progress in overcoming some of the material challenges and progress in realizing record setting edge emitting lasers, the first VCSELs operating at 1.5 μm based on GaInNAsSb and integrated photonic crystal and nanoaperture lasers.

Optical amplification at 0.54 [micro sign]m by Er3+-doped fluoride fibre

Demonstrated is a 16.5 dB all-fibre optical amplifier at 546 nm using Er3+-doped fluoride fibre for a signal power of −30 dBm by forward upconversion pumping of a 974 nm laser diode. Results show Er3+-doped fluoride fibre is a promising candidate for 0.54 µm optical amplifiers.