Ultra-broadband Near-infrared Emission Research Articles

Unlocking Cr3+-Cr3+ Coupling in Spinel: Ultrabroadband Near-Infrared Emission beyond 900 nm with High Efficiency and Thermal Stability.

Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) hold promising potential as next-generation compact, portable, and intelligent NIR light sources. Nonetheless, the lack of high-performance broadband NIR phosphors with an emission peak beyond 900 nm has severely hindered the development and widespread application of NIR pc-LEDs. This study presents a strategy for precise control of energy-state coupling in spinel solid solutions composed of MgxZn1-xGa2O4 to tune the NIR emissions of Cr3+ activators. By combining crystal field engineering and heavy doping, the Cr3+-Cr3+ ion pair emission from the 4T2 state is unlocked, giving rise to unusual broadband NIR emission spanning 650 and 1400 nm with an emission maximum of 913 nm and a full width at half-maximum (fwhm) of 213 nm. Under an optimal Mg/Zn ratio of 4:1, the sample achieves record-breaking performance, including high internal and external quantum efficiency (IQE = 83.9% and EQE = 35.7%) and excellent thermal stability (I423K/I298K = 75.8%). Encapsulating the as-obtained phosphors into prototype pc-LEDs yields an overwhelming NIR output power of 124.2 mW at a driving current of 840 mA and a photoelectric conversion efficiency (PCE) of 10.5% at 30 mA, rendering high performance in NIR imaging applications.

Ultra-broadband near-infrared emission of Cr3+-containing oxy-fluoride glass-ceramics

Broadband near-infrared (NIR) light sources cover unique optical wavelengths and are valuable in the fields of bioimaging and photodynamic therapy, night vision lighting and security monitoring. NIR phosphor converted light-emitting diode (NIR pc-LED) devices have attractive features such as tunable emission peak, low cost of production, compact in sizes and high luminous efficiency. However, heat accumulation during operation due to poor thermal conductivity of the organic resin used in packaging often causes serious reduction in luminous efficiency and accelerated degradation of the device. In present work, we developed a Cr3+-doped transparent CaF2-based oxy-fluoride glass-ceramic (GC) that showed a broadband emission of 700∼1400 nm under 470 nm excitation. The emission peaked at ∼880 nm, the full-width at half maximum was about ∼297 nm, and the photoluminescence quantum yield reached ∼31.19 %. The emission was derived from the electronic transition of Cr3+ ions from the 4T2(F) to 4A2(F). Through structural analysis and numerical simulation, we showed that during the heat treatment process, Cr3+ ions were enriched into the CaF2 crystal phase and replaced the Ca2+ in the GC host with occupied the center position of the polyhedrons, which provided a weak crystal field and led to NIR emission. We built NIR pc-LED devices using optimized GC and commercial blue LED chips, and we demonstrated the application of this NIR pc-LED in night-vision lighting. Our approaches to prepare simple and stable inorganic NIR luminous materials sealed in bulk in a transparent CaF2-based oxy-fluoride GC and to construct pc-LED devices could provide new concept to the field and have practical implications to applications in related fields.

Broadband near-infrared emission in barium gallo-germanate glasses co-doped with bismuth, chromium and erbium ions

This work presents barium gallo-germanate glasses co-doped with Bi+/Er3+ and Cr3+/Er3+ ions for NIR luminescence. The addition of Al2O3 content in the glass matrix made it possible to obtain luminescence corresponding to the 3P1→3P0 transition of Bi+ ions. Co-doping with the Bi+/Er3+ system resulted in a broad luminescence spectrum of 1.0-1.6 µm and Cr3+/Er3+ co-doping in selected glass matrix resulted in luminescence in 0.9-1.6 µm band. However, the luminescence of the Cr3+ ions is much lower than that of Er3+ ions. Full Text: PDF References T. Suzuki, G.S. Murugan, and Y. Ohishi, 'Optical properties of transparent Li2O-Ga2O3-SiO2 glass-ceramics embedding Ni-doped nanocrystals', Appl. Phys. Lett., 86(13), 131903 (2005). CrossRef N.V. Golubev et al., 'Pre-crystallization heat treatment and infrared luminescence enhancement in Ni2+-doped transparent glass-ceramics', J. Non-Cryst. Solids, 515, 42 (2019) CrossRef Z. Xu, W. Feng, T. Chen, X. Liu, and J. Qiu, 'Tuning optical properties in PbSe quantum dot-doped borosilicate glass fiber by modulation of network topology', Opt. Laser Technol., 158, 108910 (2023). CrossRef M.A. Hughes, T. Suzuki, and Y. Ohishi, 'Spectroscopy of bismuth-doped lead-aluminum-germanate glass and yttrium-aluminum-silicate glass', J. Non-Cryst. Solids, 356(44), 2302 (2010). CrossRef J. Song, Z. Zhou, B. Zhong, M. Zhang, J. Huang, and L. Han, 'Ultra-broadband near-infrared Cr3+-doped multi-phase glass-ceramics realized by the selective enrichment strategy for near-infrared spectroscopy applications', J. Alloys Compd., 968, 172126 (2023). CrossRef M.A.U. Martines, M.R. Davolos, M.J. Júnior, D.F. de Souza, and L.A.O. Nunes, 'Cr3+ and Cr4+ luminescence in glass ceramic silica', J. Lumin., 128(11), 1787 (2008). CrossRef S. Zhou, H. Dong, H. Zeng, J. Hao, J. Chen, and J. Qiu, 'Infrared luminescence and amplification properties of Bi-doped GeO2−Ga2O3−Al2O3 glasses', J. Appl. Phys., 103(10), 103532 (2008). CrossRef T. Suzuki and Y. Ohishi, 'Ultrabroadband near-infrared emission from Bi-doped Li2O-Al2O3-SiO2 glass', Appl. Phys. Lett., 88(19), 191912 (2006). CrossRef T. Minh Hau et al., 'Super broadband near-infrared emission and energy transfer in Bi-Er co-doped lanthanum aluminosilicate glasses', Opt. Mater., 35(3), 487 (2013). CrossRef H.K. Dan et al., 'Effects of Y3+on the enhancement NIR emission of Bi+-Er3+ co-doped in transparent silicate glass-ceramics for Erbium-doped fiber amplifier (EDFA)', J. Lumin., 219, 116942 (2020). CrossRef E.M. Dianov, 'Bismuth-doped optical fibers: a challenging active medium for near-IR lasers and optical amplifiers', Light Sci. Appl., 1(5) (2012). CrossRef L. Wang, L. Tan, Y. Yue, M. Peng, and J. Qiu, 'Efficient Enhancement of Bismuth NIR Luminescence by Aluminum and Its Mechanism in Bismuth‐Doped Germanate Laser Glass', J. Am. Ceram. Soc., 99(6), 2071 (2016). CrossRef Z. Jiang et al., 'Effects of Al2O3 composition on the near-infrared emission in Bi-doped and Yb-Bi-codoped silicate glasses for broadband optical amplification', J. Non-Cryst. Solids, 383, 196 (2014). CrossRef

Efficient and ultra-broadband near-infrared emission in perovskite-like Mg4Sb2O9:Cr3+ phosphor

Near-infrared (NIR) spectroscopy based on phosphor-converted NIR light-emitting-diode (LED) has extensive applications in modern life, stimulating the exploration of ultra-broadband NIR phosphors with high efficiency. Herein, Cr3+-doped perovskite-like Mg4Sb2O9 phosphor was synthesized, which exhibits a NIR emission with peak wavelength of 855 nm, and a full width at half maximum (FWHM) of about 207 nm. Upon 442 nm excitation, the quantum efficiency (QY) and absorption efficiency (AE) were determined to be 59.1 % and 48.3 %, respectively; while the luminescence intensity remained 61.5 % of room temperature at 373 K, indicating an excellent efficient and a moderate thermal stability of this material. The fabricated NIR pc-LED through combining the optimized phosphor with a 455 nm LED chip presents an output power of 20.1 mW and a photoelectronic conversion efficiency of 3.6 % under a driving current of 175 mA. These results suggest that Mg4Sb2O9:Cr3+ phosphor with excellent luminescent performance may have good potential for applications in NIR pc-LEDs.

Luminescence characteristics of ultra-broadband near-infrared emission Li3Mg2SbO6:Cr3+ phosphors and their applications in light-emitting diodes

In this study, a Li3Mg2SbO6:Cr3+ phosphor was prepared by high-temperature solid-phase reaction. The phosphors doped with 0.03Cr3+ showed broadband emission at 805 nm, a wide spectral band of 200 nm at 435 nm excitation, an internal quantum efficiency of 80.8%, and the integrated emission intensity at 423 K of Li3Mg2SbO6:Cr3+ is about 50% of that at room temperature. The phosphors conversion (pc) - light-emitting diodes (LEDs) with broadband near-infrared (NIR) emission were prepared using the Li3Mg2SbO6:Cr3+ phosphor coating on blue LED chips. They achieved 10.4% photoelectric efficiency and 60.2 mW NIR output power at 210 mA. All results showed that the Li3Mg2SbO6:Cr3+ phosphors had considerable potential in NIR spectroscopy applications.

Ultra-broadband near-infrared emission in the double-perovskite Ca2InTaO6:Cr3+ phosphor for light-emitting-diode applications

Broadband near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) have extensive applications basing on spectroscopy technology, which promote the exploration of broadband NIR phosphors. However, there are still lack of efficient ultra-broadband NIR phosphors with peak emission wavelength over 850 nm. In this work, a series of double-perovskite-type Ca2InTaO6:Cr3+ NIR phosphors were successfully prepared through a conventional high-temperature solid-state reaction process. Optimizing the Cr3+ doping concentration, the obtained phosphor exhibits an ultra-broadband emission covering 700–1300 nm with peak wavelength located at 880 nm. The full width at half maximum (FWHM) of this phosphor reaches 200 nm ascribing to the two crystallographic sites in this compound that are available for Cr3+ substitution. Upon 480 nm excitation, the photoluminescence quantum yield (PLQY) and absorption efficiency are determined to be 33.6% and 30.6%, respectively, indicating an excellent efficiency within this emission range among ultra-broadband NIR phosphors. Thus, this work provides an alternative Cr3+-activated ultra-broadband and long-wavelength NIR phosphor Ca2InTaO6:Cr3+ for the upcoming smart spectroscopy applications.

Site-selective occupation of Cr3+ ions toward ultra-broadband near-infrared emission stannate phosphors

Cr3+-activated near-infrared (NIR) luminescent materials with broadband emission have attracted extensive attentions for multipurpose NIR phosphor-converted light-emitting diodes (LED). It is widely believed that broadband NIR-emitting from optical center Cr3+ could merely made in crystal-filed caused six-coordinated sites or four-coordinated sites. Herein, taking La3Ga5SnO14 compound with six-coordinated Sn and four-coordinated Ga sites as host, we design and synthesize a new ultra-broad NIR-emitting La3Ga5Sn1-xO14:xCr3+ (LGSn1-x:xCr3+) phosphor ranging from 700 to 1500 nm via solid-state reaction. Structural analysis, low-temperature spectra investigations, and density functional theory calculations demonstrate that, in La3Ga5SnO14 (LGSn) host lattice, six-coordinated Sn sites and four-coordinated Ga sites can be successfully occupied by Cr3+ ions, leading to two distinct Cr3+ centers and an impressive broadband with full width at half maximum of up to 275 nm. At 373 K, emission intensity of LGSn0.97:3%Cr3+ phosphor maintains 43% of that at room temperature. We fabricate a NIR phosphor-converted LED device by using as-prepared LGSn0.97:3%Cr3+ phosphor and a blue LED chip and demonstrate its potential applications in night vision and food analysis. These findings provide not only an in-deep insight on site-occupation of Cr3+ residing in compounds with six-coordinated sites and four-coordinated sites but also feasible method of designing ultra-broadband NIR phosphors.

Achieving the ultra-broadband near-infrared La3SnGa5O14:Cr3+ phosphor via multiple lattice sites occupation for biological nondestructive detection and night-vision technology

Currently, near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have become a research hotspot, however, the NIR phosphors continue to face the problems of narrowband emission and poor thermal stability. Therefore, in order to solve these problems, La3SnGa5O14:xCr3+ phosphors with ultra-broadband NIR emission were obtained by multiple lattice sites occupation, featuring ultra-broadband emission in the range of 650–1300 nm with full width at half-maximum (FWHM) up to 333 nm under 437 nm excitation. By tuning the concentration of Cr3+, the FWHM value can reach 333–417 nm La3SnGa5O14:Cr3+ also exhibits favorable thermal stability, maintaining 90.5% and 67% of the initial intensity at 373 K and 423 K, respectively. The NIR pc-LEDs were manufactured by combining the blue light chip with La3SnGa5O14:Cr3+ phosphor. When the NIR pc-LED was switched off, no image could be generated from the infrared camera. Instead, the image captured by the infrared camera was visible in the light of the NIR pc-LED lamp. Such results imply that La3SnGa5O14:Cr3+ may be a prospective candidate for future biological accurate nondestructive detection and night-vision technology.

Optimizing Broadband Near-Infrared Emission in Bi/Sn-Doped Aluminosilicate Glass by Modulating Glass Composition.

The Bi/Sn-doped aluminosilicate glass samples were prepared using a melting–quenching method and their near-infrared (NIR) emission properties were studied. An ultra-broadband NIR emission ranging from 950 nm to 1600 nm was observed in all samples under 480 nm excitation, which covered the whole fiber low-loss window. The NIR emission spectrum showed that the maximum emission peak was about 1206 nm and the full width at half maximum (FWHM) was about 220 nm. Furthermore, the NIR emission intensity strongly depends on the composition of the glass, which can be optimized by modulating the glass composition. The Bi0 and Bi+ ions were the NIR luminescence source of the glass samples in this paper. The Bi/Sn-doped aluminosilicate glass has the potential to become a new type of core fiber material and to be applied to optical fiber amplifiers (OFAs), based on its excellent performance in ultra-broadband NIR emission.

Achieving a tunable and ultra-broadband near-infrared emission in the Ga2-2xZnxGexO3:Cr3+ phosphor.

Near-infrared (NIR) spectroscopy (700-1100 nm) based on a phosphor-converted light-emitting diode (pc-LED) has multi-functional applications in bio-imaging, night-vision, and food quality analysis, simulating the development of efficient and ultra-broadband NIR phosphors. Herein, a series of tunable and ultra-broadband NIR phosphor Ga2-2xZnxGexO3:Cr3+ was successfully produced by a [Zn2+-Ge4+] unit co-substituting a [Ga3+-Ga3+] unit in Ga2O3:Cr3+. With the increasing amount of [Zn2+-Ge4+] incorporation, the emission peak can be tuned from 726 to 808 nm, and the maximum FWHM can be extended from 126 to 190 nm. However, the excitation peak position remained nearly unchanged in the blue light region, enabling this material to perfectly match the InGaN blue LED chip. Although the gradually enhanced electron-lattice coupling and low energy barrier for thermal quenching caused by this co-substitution lead to a decrease in the photoluminescence quantum yield (PLQY) and thermal stability, respectively, the absolute values of these two criteria can be well maintained. Finally, to evaluate the practical applications, prototype NIR pc-LEDs were fabricated using these materials combined with 450 nm LED chips. Under the same conditions, the NIR output power and photoelectronic conversion efficiency of these devices are superior to those fabricated using the well-known ScBO3:Cr3+ phosphor. These results demonstrate that this series of materials with tunable and ultra-broadband NIR emissions has great potential for NIR pc-LED applications.

PbS quantum dots and BaF2:Tm3+ nanocrystals co-doped glass for ultra-broadband near-infrared emission [Invited

With the rapid growth of optical communications traffic, the demand for broadband optical amplifiers continues to increase. It is necessary to develop a gain medium that covers more optical communication bands. We precipitated PbS quantum dots (QDs) and BaF2:Tm3+ nanocrystals (NCs) in the same glass to form two independent emission centers. The BaF2 NCs in the glass can provide a crystal field environment with low phonon energy for rare earth (RE) ions and prevent the energy transfer between RE ions and PbS QDs. By adjusting the heat treatment schedule, the emission of the two luminescence centers from PbS QDs and Tm3+ ions perfectly splices and covers the ultra-broadband near-infrared emission from 1200 nm to 2000 nm with bandwidth over 430 nm. Therefore, it is expected to be a promising broadband gain medium for fiber amplifiers.

D2h-Symmetric Tetratellurium Clusters in Silicate Glass as a Broadband NIR Light Source for Spectroscopy Applications.

Broadband near-infrared (NIR) light sources present attractive opportunities for potential applications in high-capacity telecommunication, temperature sensing, energy conversion, and NIR spectroscopy. While significant effort has been spent on materials doped with rare-earth and transition-metal ions, the achievement of these materials with ultrabroadband NIR emission and desired wavelength region remains a long-standing challenge, especially operating in the spectral region between 700 and 1300 nm. Here, such emission is developed in tellurium (Te) cluster-doped silicate glass for the first time. Furthermore, the mechanism of the NIR luminescence due to D2h-symmetric tetratellurium (Te4) clusters is identified by density functional theory (DFT) calculations. For intense luminescence, a model for the generation and stabilization of Te clusters by tailoring topological cages via adjustment of the Na2O and Al2O3 contents and by optimizing the content of the dopant is proposed. Various stable Te clusters embedded into glass exhibit intense visible (Vis) to NIR broadband luminescence (400-1300 nm) with a spectral gap of 900 nm. In a demonstration experiment, a light-emitting diode (LED) device is fabricated from Te cluster-doped glass. This study opens a new opportunity for Te cluster-doped glass as a broadband NIR light source for spectroscopy applications.

Improvement of ultra-broadband near-infrared emission at around 1.0 µm in Nd3+-Er3+-Pr3+ tri-doped tellurite glasses

Nd3+-Er3+-Pr3+ tri-doped tellurite glasses with lower phonon energy (768 cm−1) were prepared by conventional melt-quenching method. Under the excitation of 488nm, an ultra-broadband emission from 760 to 1150 nm with full-width at half-maximum (FWHM) of about 262 nm was observed in the prepared Nd3+-Er3+-Pr3+ tri-doped glass sample, larger than that of the recently reported glasses. The DSC curve shows that the prepared tellurite glass has high glass transition temperature (Tg=382°C) and good thermal stability (ΔT=203°C). The gain coefficient, maximum absorption and emission cross section of Nd3+-Er3+-Pr3+ tri-doped tellurite glass for Nd3+:4F3/2→4I9/2 and Er3+:4I11/2→4I15/2 transitions are calculated as 0.41 cm−1, 0.80 × 10−20 cm2, 1.07 × 10−20 cm2, 0.35 cm−1, 0.37 × 10−20 cm2 and 0.45 × 10−20 cm2, respectively. Compared with the recently reported glasses, these values were effectively improved. This means that the prepared tellurite glass has better fluorescence emission and laser gain performance.

Improvement of ultra-broadband near-infrared emission in Nd3+-Er3+-Pr3+ tri-doped tellurite glasses

Abstract Nd3+-Er3+-Pr3+ tri-doped tellurite glasses with lower phonon energy (766 cm−1) were prepared by conventional melt-quenching method. Under the excitation of 488 nm, an ultra-broadband emission from 1250 to 1650 nm with full-width at half-maximum (FWHM) of about 332 nm was found in Nd3+-Er3+-Pr3+ tri-doped tellurite glass, larger than that of recently reported tellurite glasses. The DSC curve showed that the prepared glass had a high glass transition temperature (Tg = 381 °C) and good crystallization resistance (ΔT = 195 °C). Raman spectra and XRD pattern revealed the information of different vibrational units and the amorphous structure of the prepared glass. The maximum absorption cross-section, emission cross-section and gain coefficient of the prepared tellurite glass were calculated as 1.05 × 10−20 cm2, 1.34 × 10−20 cm2 and 1.55 cm−1, respectively. Compared with the recently reported glasses, these values were improved. This indicates that better laser gain and fluorescence emission could be obtained in the prepared tellurite glass. The results showed that Nd3+-Er3+-Pr3+ tri-doped tellurite glass is a promising near-infrared optical material.

Structural, thermal and broadband NIR emission properties of Nd3+/Pr3+/Ag NPs co-doped tellurite glass

Nd3+/Pr3+ co-doped tellurite glasses containing metallic Ag NPs were synthesized by melt-quenching and heat-treating techniques. The amorphous structural nature, fundamental vibrational units and good thermal stability of the prepared tellurite glasses were confirmed by X-ray diffraction (XRD) pattern, Raman spectrum and differential scanning calorimeter (DSC) curve, respectively. The precipitated Ag NPs in a glass matrix with an average diameter ∼5 nm were revealed by transmission electron microscopy (TEM) image, and the radiative property of Nd3+ and Pr3+ ions was evaluated from the absorption spectrum by Judd-Ofelt theory. Under the excitation of 488 nm Xenon lamp, two broadband near-infrared emissions covering 800-1100 nm and 1250-1650 nm ranges were observed from the fluorescence spectrum. The former originated from the transitions of Pr3+:3P1,0→1G4, Pr3+:1D2→3F4,3, Nd3+:4F3/2→4I11/2 and Nd3+:4F3/2→4I9/2, while the latter was contributed by the Pr3+:1G4→3H5, Pr3+:1D2→1G4, Pr3+:3F3→3H4 and Nd3+:4F3/2→4I13/2 transitions. With the introduction of Ag NPs, the emission intensity of two broadband near-infrared emissions was further enhanced, in which the peak emission intensity of 1250-1650 nm band was increased by about 56% and the FWHM is up to 250 nm. The obtained results indicate that Nd3+/Pr3+/Ag NPs co-doped tellurite glass has great potential in realizing ultra-broadband near-infrared emission covering O-, E- and S-bands simultaneously.

Multi-band near-infrared emission in low concentration bismuth doped alkaline earth alumino-boro-germanate glass

Ultra-broadband near-infrared emission mainly consisting of three bands around 940 nm, 1180 nm and 1500 nm was investigated under excitation at 460 nm in RO-Al2O3–B2O3-GeO2 (R = Mg, Ca, Sr and Ba) glasses with 0.005 mol% Bi2O3 doping. With the radius increasing of alkaline earth ion, the first and the third bands became stronger while the second one became weaker gradually, but their photoluminescence thermal stability and quantum yield declined gradually. The luminescence origination should be multi-type bismuth active centers (BACs). Furthermore, energy levels of the BAC assigning to the band around 1500 nm (BAC-1500) were analyzed through a contour plot of near-infrared emission intensity, excitation spectra and temperature dependent PL spectra. At last, the glass structure was studied by Raman and FT-IR spectra, molar volume and Vickers hardness. BAC-1500 should prefer the glass matrix with a looser framework, which indicates there was a competitive formation of different BACs in the glass.

Ultra-broadband near-infrared emission CuInS2/ZnS quantum dots with high power efficiency and stability for the theranostic applications of mini light-emitting diodes.

Broadband near-infrared CuInS2/ZnS quantum dots with up to 94.8% quantum yield were synthesized with fast precursor decomposition leading to monomer conversion improvement. In the mini-LED package, the device showed high power efficiency and stability was also demonstrated with a penetration test and vein imaging showing its potential biomedical application in the theranostics field.

Ultra-broadband 1.0 μm band emission spectroscopy in Pr3+/Nd3+/Yb3+ tri-doped tellurite glass.

Tellurite glasses doped with trivalent Pr3+, Nd3+ and Yb3+ ions were prepared using conventional high-temperature melt-quenching technique and their optical absorption, near-infrared emission, X-ray diffraction (XRD), Raman spectrum, and differential scanning calorimeter (DSC) curve were measured. Upon excitation at 488 nm, an ultra-broadband near-infrared emission extending from 800 to 1120 nm was found to appear owing to the overlapping of the emission bands centered at 900 and 1035 nm of Pr3+, 880 and 1060 nm of Nd3+ as well as 978 nm of Yb3+, respectively. The energy transfer mechanism among Pr3+, Nd3+ and Yb3+ ions which was responsible for the observed ultra-broadband near-infrared emission was investigated to understand the luminescent phenomena. In addition, Judd-Ofelt theory was applied to predict the radiative properties of doped rare-earth ions, and some important radiative parameters such as radiative transition probability, branching ratio and radiative lifetime were derived. Meanwhile, the structural information of amorphous nature and vibrational units was revealed by the XRD pattern and Raman spectrum. Also, the DSC curve displayed the good thermal stability to resist thermal damage for studied tellurite glass with high glass transition temperature. The results indicate that Pr3+/Nd3+/Yb3+ tri-doped tellurite glass is a promising material for ultra-broadband fiber lasers operating around 1.0 μm near-infrared band.

In situ instant generation of an ultrabroadband near-infrared emission center in bismuth-doped borosilicate glasses via a femtosecond laser

Bismuth (Bi)-doped photonic materials, which exhibit broadband near-infrared (NIR) luminescence (1000–1600 nm), are evolving into interesting gain media. However, the traditional methods have shown their limitations in enhancing Bi NIR emission, especially in the microregion. Consequently, the typical NIR emission has seldom been achieved in Bi-doped waveguides, which highly restricts the application of Bi-activated materials. Here, superbroadband Bi NIR emission is induced in situ instantly in the grating region by a femtosecond (fs) laser inside borosilicate glasses. A series of structural and spectroscopic characterizations are summoned to probe the generation mechanism. And we show how this novel NIR emission in the grating region can be enhanced significantly and erased reversibly. Furthermore, we successfully demonstrate Bi-activated optical waveguides. These results present new insights into Bi-doped materials and push the development of broadband waveguide amplification.

Ultra-broadband near-infrared emission in bismuth borosilicate glasses incorporated with Er3 +, Tm3 +, and Yb3 + ions

Bismuth containing glasses are interesting photonic materials due to their broadband emission properties in the near-infrared wavelength range. Bismuth alumino-borosilicate glasses co-doped with Er3+, Tm3+, and Yb3+ ions were prepared by the conventional glass melting process and their optical absorption, near-infrared emission, and lifetime characteristics were investigated. Upon pumping at 800nm with a Ti:sapphire laser, a very broad emission band covering at 900–1700nm was found to appear due to overlapping of the emissions centering at 1003, 1266, 1536, and 1643nm from the co-doped ions of Yb3+, Bi, Er3+, and Tm3+, respectively. The emission intensity and the lifetime of the emission bands were significantly influenced by the addition of Yb2O3. The pump energy absorbed by Bi was transferred to Yb3+ and Er3+ ions and the amount of the transferred energy was enhanced with the increase of Yb2O3. The energy transfer efficiency from Bi to the co-doped rare earth ions was ~4.0% at 2mol% of Yb2O3.