Erbium Chloride Silicate Research Articles

Self-optimized single-nanowire photoluminescence thermometry

Nanomaterials-based photoluminescence thermometry (PLT) is a new contact-free photonic approach for temperature sensing, important for applications ranging from quantum technology to biomedical imaging and diagnostics. Even though numerous new materials have been explored, great challenges and deficiencies remain that hamper many applications. In contrast to most of the existing approaches that use large ensembles of rare-earth-doped nanomaterials with large volumes and unavoidable inhomogeneity, we demonstrate the ultimate size reduction and simplicity of PLT by using only a single erbium-chloride-silicate (ECS) nanowire. Importantly, we propose and demonstrate a novel strategy that contains a self-optimization or “smart” procedure to automatically identify the best PL intensity ratio for temperature sensing. The automated procedure is used to self-optimize key sensing metrics, such as sensitivity, precision, or resolution to achieve an all-around superior PLT including several record-setting metrics including the first sensitivity exceeding 100% K−1 (~138% K−1), the highest resolution of 0.01 K, and the largest range of sensible temperatures 4–500 K operating completely within 1500–1800 nm (an important biological window). The high-quality ECS nanowire enables the use of well-resolved Stark-sublevels to construct a series of PL intensity ratios for optimization in infrared, allowing the completely Boltzmann-based sensing at cryogenic temperature for the first time. Our single-nanowire PLT and the proposed optimization strategy overcome many existing challenges and could fundamentally impact PL nano-thermometry and related applications such as single-cell thermometry.

Enhancement of sensitized photoluminescence of erbium chloride silicate through regulating annealing

Erbium chloride silicate (ECS) nanocrystals and Si nanocrystals (Si NCs) co-embedded in silica films were prepared. And the sensitized luminescence of ECS was realized through interparticle energy transfer (IPET) in solid matrix. We focus on the effect of annealing temperature on the film microstructure and sensitized luminescence. The samples annealed at 1100 °C have a moderate level of energy transfer efficiency and total Er3+ concentration capable of radiative recombination. At the same time, they also have high luminescence intensity of Si NCs. Therefore, the samples annealed at 1100 °C have good sensitizing luminescence performance of ECS. The strong luminescence intensity of sensitizers Si NCs and adjacent crystalline ECS nanocrystals are the keys to achieve excellent IPET in the solid matrix. The results provide a basis for optimizing sensitized luminescence of erbium compounds by regulating annealing.

Controlled growth of single-crystalline erbium chloride silicate with long-lived fluorescence.

Single-crystalline erbium chloride silicates have attracted extensive attention due to their high gain compatibility and silicon compatible properties. Long-lived near-infrared fluorescence is critical for reducing a pump density threshold when erbium containing materials are used as active devices. Here we developed a single-source chemical vapor deposition (CVD) method to grow high-quality single-crystalline erbium chloride silicate nanostructures. The growth mechanism is found composing of two steps, where silicon source comes from the minor evaporation of silicon substrate. The prepared single-crystalline erbium chloride silicate nanowires own diameter of about 200 nm with few lattice defects, and the fluorescence lifetime reaches up to 7.4 ms. A nanoscale thermometer based on their visible band fluorescence is realized.

Efficient Sensitized Photoluminescence from Erbium Chloride Silicate via Interparticle Energy Transfer.

In this study, we prepare Erbium compound nanocrystals and Si nanocrystal (Si NC) co-embedded silica film by the sol-gel method. Dual phases of Si and Er chloride silicate (ECS) nanocrystals were coprecipitated within amorphous silica. Effective sensitized emission of Er chloride silicate nanocrystals was realized via interparticle energy transfer between silicon nanocrystal and Er chloride silicate nanocrystals. The influence of density and the distribution of sensitizers and Er compounds on interparticle energy transfer efficiency was discussed. The interparticle energy transfer between the semiconductor and erbium compound nanocrystals offers some important insights into the realization of efficient light emission for silicon-based integrated photonics.

A measurement method of the intrinsic optical absorption spectrum of 1D nanomaterials and its application to erbium chloride silicate nanowires

Measurement of the absolute absorption coefficient of various nanomaterials over a wide spectral range is important for a variety of photonic applications but is very challenging due to strong scatterings from the intrinsically granular features of nanomaterials. We report in this paper a two-step method to determine the absorption spectrum on the absolute scale for an ensemble of nanowires: first, the relative absorption spectrum over a wide spectral range is measured from the nanowire ensemble in a carefully designed experiment using integrating sphere. Second, the absorption coefficient at a single wavelength is measured on a single nanowire to serve as the calibration of the relative spectrum. The combination of the two measurements allows the determination of the absolute absorption spectrum over a wide range. We then apply this measurement strategy to a relatively new class of nanowire materials, the erbium compound (erbium chloride silicate (ECS)) nanowires to determine its absorption spectrum. The absorption coefficient in a wide spectral range from near infrared to visible was determined for the first time for this unique erbium compound material. The measurement strategy is generally applicable to other 1D nanomaterials. The precise determination of the ECS absorption spectrum in such a wide spectral range is of vital importance to various applications of ECS nanowires including nanolasers, solar cells, and nanoscale amplifiers.

Giant optical gain in a single-crystal erbium chloride silicate nanowire

Rare-earth optical materials with large optical gain are of great importance for a wide variety of applications in photonics and quantum information due to their long carrier lifetimes and quantum coherence times, especially in the realization of efficient lasers and amplifiers. Until now, such materials have achieved a gain of less than a few dB cm–1, rendering them unsuitable for applications in nanophotonic integrated circuits. Here, we report the results of the signal enhancement and transmission experiments on a single-crystal erbium chloride silicate nanowire. Our experiments demonstrate that a net material gain over 100 dB cm–1 at wavelengths around 1,530 nm is possible due to the nanowire's single-crystalline material quality and its high erbium concentration. Our results establish that such rare-earth-compound nanowires are a potentially important class of nanomaterials for a variety of applications including, for example, subwavelength-scale optical amplifiers and lasers for integrated nanophotonics, and quantum information. Erbium chloride silicate nanowire promises optical gain for nanophotonic circuits.

Single crystal erbium compound nanowires as high gain material for on-chip light source applications

Integrated photonics requires high gain optical materials in the telecom wavelength range for optical amplifiers and coherent light sources. Erbium (Er) containing materials are ideal candidates due to the 1.5 μm emission from Er3+ ions. However, the Er density in typical Er-doped materials is less than 1020 cm–3, thus limiting the maximum optical gain to a few dB/cm, too small to be useful for integrated photonic applications. Er compounds could potentially solve this problem since they contain much higher Er3+ density. So far the existing Er compounds suffer from short lifetime and strong upconversion effects, mainly due to poor crystal qualities. Recently, we explore a new Er compound: erbium chloride silicate (ECS, Er3(SiO4)2Cl) in the form of nanowire, which facilitates the growth of high quality single crystal with relatively large Er3+ density (1.62 × 1022 cm–3). Previous optical results show that the high crystal quality of ECS material leads to a long lifetime up to 1 ms. The Er lifetime-density product was found to be the largest among all the Er containing materials. Pump-probe experiments demonstrated a 644 dB/cm signal enhancement and 30 dB/cm net gain per unit length from a single ECS wire. As a result, such high-gain ECS nanowires can be potentially fabricated into ultra-compact lasers. Even though a single ECS nanowire naturally serves as good waveguide, additional feedback mechanism is needed to form an ultra-compact laser. In this work, we demonstrate the direct fabrication of 1D photonic crystal (PhC) air hole array structure on a single ECS nanowire using focused ion beam (FIB). Transmission measurement shows polarization-dependent stop-band behavior. For transverse electric (TE) polarization, we observed stop-band suppression as much as 12 dB with a 9 μm long airholed structure. Through numerical simulation, we showed that Q-factor as high as 11000 can be achieved at 1.53 μm for a 1D PhC micro-cavity on an ECS nanowire. Such a high Q cavity combined with the high material gain of ECS nanowires provides an attractive solution for ultra-compact lasers, an important goal of this research.

Long lifetime, high density single-crystal erbium compound nanowires as a high optical gain material

Erbium-containing materials of long lifetime and high Er density are important for achieving strong luminescence and high optical gain in compact integrated photonics devices. We have systematically studied the lifetime and crystal quality as a function of growth conditions for an erbium compound that we recently reported, erbium chloride silicate (ECS). The lifetime for the best quality ECS nanowires can be as long as 540 μs, the longest for high-density Er-materials, representing a lifetime-density product as high as 8.7 × 1018 s cm−3. Such high density, long lifetime erbium materials can find many interesting applications such as compact lasers or amplifiers.

Single-crystal erbium chloride silicate nanowires as a Si-compatible light emission material in communication wavelength

We report on the first synthesis and structural characterizations of a new Erbium (Er) compound, the erbium chloride silicate (ECS, Er3Cl(SiO4)2) single crystal in a Si-ECS core-shell nanowire form. The Er-concentration in ECS at 1.6x1022 cm−3 is three orders of magnitude higher than that of the Er-doped materials. Photoluminescence spectra at both low and room temperatures exhibit well separated sharp emission lines in the near infrared region. The new single-crystal erbium-compound nanowires provide a unique Si-compatible material for high-gain light emission in communication wavelength and for many other photonic applications.