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Colloidally prepared copper sulphide (Cu2-xS) nanocrystals are possessing superior structural and optical properties owing to the presence of copper vacancies. The application of colloidal Cu2-xS nanocrystals are critically analysed for several optoelectronic applications. Furthermore, colloidally prepared Cu2-xS nanocrystals undergo facile process such as cation exchange, additives induced structural modifications etc. Therefore, it is important to evaluate the optical properties of these nanomaterials in order to apply them for future optoelectronic applications. Out of other properties, localized surface plasmon resonance (LSPR) by controlling composition of the Cu2-xS nanocrystals is investigated with more curiosity and much useful findings are derived for the potential applications. Because of the near-infra-red (NIR) absorption, the spectral absorption could be tuned and the LSPR arising from the non-stoichiometric Cu2-xS nanocrystals could be used for numerous applications. This chapter discusses about the current developments associated with the colloidally prepared Cu2-xS nanocrystals and their LSPR property in several potential applications. The experimentally demonstrated results are compared with the future predictions in this research area.

We investigated the effect of Gd3+ and Ga3+ on Yb:YAG emission at cryogenic temperatures by preparing ceramic pellets by solid state reaction method with different Gd3+ and Ga3+ content. Incorporation of Gd3+ shows only a small effect on spectral broadening whereas incorporation of Ga3+ in Yb:YAG results in significant broadening. Such an inhomogeneous broadening is due to the replacement of larger Ga3+ ion in two different cationic sites of Al3+ which causes a change in local crystal field on the Yb3+ site.

Compact diode-pumped solid-state lasers (DPSSLs) have become ubiquitous due to their vast scientific and technological applications. Especially in medicine, one can see the use of DPSSLs in the field of dermatology, dentistry, general surgery, urology etc. This is mainly due to the replacement of pump source from flash lamp to more efficient and cost-effective laser-diodes, as well as the availability of crystalline/ceramic solid-state laser gain materials for a specific wavelength region [1] . Concerning the application in ophthalmology, a light source in the yellow region (577 nm) is of great interest especially for retinal photocoagulation treatment [2] . The peak absorption of oxyhemoglobin and negligible macular xanthophyll absorption at 577 nm wavelength enable the ophthalmologist to perform retinal photocoagulation treatment with minimum risk and with lower laser energy compared to green or other wavelengths. However, achieving 577 nm wavelength is not an easy task because of non-availability of proper gain media that emit at this particular wavelength. Bearing the above-mentioned facts, here in this work, we achieved 577 nm wavelength by constructing a laser setup with proper combination of gain, Raman and frequency doubling media.

Monoclinic ytterbium-lithium codoped zinc monotungstate crystal (Yb3+,Li+:ZnWO4) is a promising material for laser opertation at ~1.06 μm. Absorption, σabs, and stimulated-emission, σSE, cross-sections are determined for light polarized along the optical indicatrix axes, E || Np, Nm and Ng. At room temperature, the maximum σSE amounts to 2.81 × 10−20 cm2 at 1055.6 nm (for E || Np) and the gain bandwidth reaches ~22 nm (for E || Ng). The radiative lifetime of the upper laser level is 0.37 ms. The Stark splitting of Yb3+ multiplets is resolved with low-temperature (6 K) spectroscopy revealing a relatively large total splitting of the ground-state, ΔE(2F7/2) = 804 cm−1, being remarkably high as compared to other Yb3+-doped tungstate crystals. A notable inhomogeneous broadening of the zero-phonon line is detected at 6 K. A continuous-wave diode-pumped 1.8 at.% Yb3+,Li+:ZnWO4 laser generated a maximum output power of 2.90 W at ~1059 nm with a slope efficiency of 57.9% and a linearly polarized output (E || Np). Yb3+,Li+:ZnWO4 is attractive for broadly tunable and mode-locked oscillators.

Arsenic (As), one of the highest harmful pollutants found in drinking/groundwater, is owing to have unfavourable impacts, for example, skin disease, on human health. The new Environmental Protection Agency (EPA) assigned the maximum contaminations of arsenic in groundwater is 10μg/L, and several drinking water plants are needing extra treatment to accomplish this standard. In recent years, several researchers have been attempting to discover practical and expendable adsorbents for some water filtration systems that are utilized in many arsenic endemic territories. Metal oxide-based adsorbents had been proved to be the best strategies for arsenic expulsion/removal. This chapter reviews the removal of both arsenite (As III) and arsenate (As V) species from drinking/groundwater. Also, we give an overview of traditionally applied strategies to expel both arsenic species to incorporate coagulation-flocculation, oxidation, and membrane techniques. More focus has been given to adsorption methods, type of adsorption and factors affecting adsorption. Moreover, brief summary has been given for an advancement on the efficacy of different nanomaterials and composites for the polluted water treatment. A basic examination of the most generally explored nanomaterials is highlighted.

Titanium dioxide (TiO2) is a naturally occurring oxide of titanium. It has a wide range of applications. It has three metastable phases, which can be synthesized easily by chemical routes. Usage of TiO2 in thin-film solar cells has gained much attention in increasing the performance of the cell. The objectives are to harvest the freely available earth’s energy and to gain expertise in yielding a maximum conversion efficiency. Various strategies are employed to face the challenges in improving the efficiency of solar cells. This study provides a broad view of the usage of different forms of TiO2 layers, like nanochannel, porous, nanotubes, and mesoporous layers, in enhancing electron injection between the layers. Various types include photoanodes in thin-film solar cells, perovskite cells, dye-sensitized solar cells, metal oxide solar cells, quantum dot solar cells, and tandem solar cells.

We present a diode-pumped, electro-opticallyQ-switched Tm:YAG laser with a cryogenically cooled laser crystal at 120 K. Output pulses of up to 2.55 mJ and 650 ns duration were demonstrated in an activelyQ-switched configuration with a repetition rate of 1 Hz. By using cavity dumping the pulse duration was shortened to 18 ns with only a slightly lower output energy of 2.22 mJ. Furthermore, using a simplified rate equation model, we discuss design constraints on the pump fluence in a pulse pump approach for Tm:YAG to maximize the energy storage capability at a given pump power.

Nearly three decades of significant academic and commercialization progress, appreciations have to be credited for Li+ ion-based rechargeable secondary batteries, which conquered the entire world. The Li+ ion batteries dictate the consumer battery market and are considered crucial for the practical realization of plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and electric vehicles (EVs). Recently, post-lithium–ion batteries, particularly Na, K, Mg, and Zn, and Al–ion batteries have also been intensively explored for various energy storage tenders due to their natural abundance, low cost, and environmental safety of these materials. The utilization of metal oxides in battery application is tremendous and, an example, the first commercial lithium ion batteries by Sony Co. with LiCoO2 as a cathode. Recently, Ni-rich layered oxide-based lithium ion batteries are on an edge of commercialization. The focus on battery research had increased drastically from 2010, and still metal oxide-based cathodes/anodes are researched exclusively due to their significant physicochemical properties. This chapter emphasizes electrochemical properties of various metal oxide-based electrode materials for various secondary rechargeable energy storage applications including sodium ion batteries (SIBs), potassium ion batteries (PIBs), and zinc ion batteries (ZIBs).

Thin films of metal oxides have been extensively studied for various applications because of their durability, lower cost and lower toxicity, excellent chemical, magnetic, electrical and optical properties. A fusion of electrical and optical properties led to the growth of optoelectronic devices for a variety of applications including displays, light-emitting diodes, photovoltaic cells, photodetectors, optical storage, medicine, and so on. Optoelectronic devices have revolutionized our daily lives with their potentials in various aspects. An extensive research on materials for these devices has to be credited for the improvement in their performance over the years. Several metal oxide thin films have been developed over the decades, and their optical, electrical, mechanical properties have been studied to determine the suitability for advanced optoelectronic devices. Several fabrication techniques employed over the decades helped to improve the quality of the fabricated thin films which is quite critical for the device performance. In this chapter, we give an overview of metal oxide semiconductors, several optoelectronic properties, and various optoelectronic applications based on metal oxide semiconducting thin films. More focus has been given on display applications and its related metal oxide materials. In addition, brief summary of other optoelectronic devices such as light-emitting diodes (LEDs), transparent conducting oxides (TCOs), solar cells, ultraviolet (UV) photodetectors, gas sensors, and heat mirrors has been given. Each application is explained along with its working principle and the material widely used for such applications. Various thin film fabrication techniques are discussed, and the fabrication procedure of a metal oxide thin film is highlighted for each technique.

We present the spectroscopic and laser characteristics of a 3 at.% Tm:Y2O3 transparent ceramic at cryogenic temperatures. An absorption cross section of 4.7 × 10−21 cm2 with a bandwidth of 0.7 nm centered at 793.3 nm and an emission cross section of 29.0 × 10−21 cm2 centered at 1930.9 nm were estimated at 80 K. Continuous-wave laser operation was achieved using broadband and VBG stabilized laser diodes emitting around 793 nm as pump sources. With the VBG pump diode, a maximum output power of 6.4 W was achieved at 80 K corresponding to a slope efficiency of 52.0% with respect to absorbed power.

We demonstrated a cryogenically cooled Tm:Y2O3 master oscillator emitting around 1932.5 nm, which was tuned from 10 to 1000 Hz. Maximum pulse energy of 1.8 mJ (10 Hz) was achieved with 32 ns pulse duration.

We report on continuous-wave and pulsed laser characteristics of Yb:Y2O3 transparent ceramic at cryogenic temperatures. A VBG stabilized pump diode emitting at 976 nm which matches with the zero-phonon line of the gain media was employed. At 100 K, a maximum continuous-wave output power of 12 W, around three times than that of 300 K and a slope efficiency of 54.4%, 2.4 times than that of 300 K was achieved using an output coupler transmission of 50% with respect to incident power. In passive Q-switched regime, using a Cr:YAG saturable absorber with an initial transmission of 85%, a maximum energy of 0.46 mJ per pulse was obtained with a peak power of 1.64 kW at a repetition rate of 19.6 kHz.

Among the excellent active media, thulium-doped yttrium oxide (Tm:Y 2 O 3 ), belonging to the sesquioxide family of laser materials, stands out because it shows very high thermal conductivity, broad gain spectra and a relatively low maximum phonon energy, which makes it very suitable for two micron laser operation in several temporal regimes [1]. However, its main limitation is the crystal growth methodology due to its high melting point making the growth of high quality crystals with large size to be a tedious and expensive task. This is confirmed by the fact that there are only few suppliers in the world. The transparent ceramic fabrication process solves these limitations and paves the way to spread the ceramic-based gain media in the future commercial solid-state laser systems [2]. Besides the substitution of the crystalline gain media by the ceramic ones, cooling them to cryogenic temperatures suppresses thermal issues and enhances the material's properties, such as thermal conductivity and transition cross-sections, being prerequisites for the development of high power lasers. To date, no deep studies on Tm:Y 2 O 3 either in crystalline or ceramic form at cryogenic temperatures are found.

Cryogenically cooled diode-pumped solid-state lasers have gained significant attention among laser community for power scaling along with excellent spatial beam quality. This is due to the suppression of thermo-optic distortions and enhancement in spectroscopic properties of the laser material at such low temperatures [1]. To date, to develop lasers of this kind, Yb:YAG was mainly used as the active material because of ease of availability in the market and ease of pumping using commercially available laser diodes. One of the cubic sesquioxides, Yb3+ doped Y 2 O 3 in ceramic form is a promising material for high-power solid state lasers because of its superior thermal, mechanical and optical properties compared to that of Yb:YAG [2]. Here we report the laser performance of Yb:Y 2 O 3 transparent ceramic at cryogenic temperatures using a VBG stabilized laser diode as a pump source.

We present the absorption spectroscopy and continuous-wave laser operation of Tm:YLF at cryogenic temperatures. At 100 K, a maximum output power of 2.55 W corresponding to a maximum slope efficiency of 22.8% is obtained using 15% output coupling transmission. The output laser wavelength is centered at 1877 nm for Elc.

We demonstrated a master oscillator power amplifier system using cryogenically cooled Tm:Y2O3 transparent ceramics. The electro-optically switched master oscillator acted as a seed source and could be tuned from 1 to 100 Hz. A maximum pulse energy of 1.35 mJ with a pulse duration of 30 ns amounting to a peak power of 45 kW was obtained at 10 Hz. The power amplification via double-pass geometry achieved maximum single pulse energy of 2.94 mJ at 10 Hz with a pulse duration of 32 ns. The results showed the pulsed lasing potential of Tm:Y2O3 transparent ceramics at cryogenic temperatures. This gain material can be considered as an alternative gain medium for high average and peak power laser development around 2 µm in nano-second regime.

We report on diode pumped cryogenic Yb: Lu3Al5O12 (LuAG) laser in the continuous-wave and pulsed regime. Under given experimental condition, we determined an optimum crystal temperature of 140 K for efficient laser operation. A maximum output power of 10.46 W with slope efficiency values of 48.6 and 67% with respect to incident and absorbed power respectively were achieved for an output coupler transmission of 40%. Yb:LuAG laser performed significantly better at 140 K with an output power 16 times and slope efficiency 7 times better than the values at 240 K. Self-starting passively Q-switched Yb:LuAG lasers were also characterized using Cr:YAG saturable absorbers with three different initial transmissions. A maximum pulse energy of 0.215 mJ and a peak power of 1.46 kW were obtained corresponding to the shortest pulse duration of 148 ns.

Development of high energy laser sources with nanosecond pulses at several hertz values for repetition rate has been very attractive in recent years due to their great potential for practical applications. With the recent advancement in fabricating large size laser quality transparent ceramics, diode pumped solid-state laser generating pulse energy of 100 J at 10 Hz has been recently realized at HiLASE center using Yb:YAG ceramic with Cr:YAG cladding. This review discusses Yb based high energy lasers, specific laser geometries for efficient thermal management and the role of transparent ceramics in such diode pumped high-energy-class solid-state lasers around the world.

We study cryogenic laser operation of an Yb-doped KLu(WO

In recent years, the development of compact all solid-state lasers has attracted the scientific community because of their vast scientific and technological applications. In particular, ytterbium (Yb3+) laser sources have been developed with a great number of hosts, due to the promise of the Yb3+ ion related to the very simple energy level structure and absence of higher energy levels, as well as a small quantum defect. However, at room temperature (RT) these materials behave as quasi three-level lasers due to a finite population of the ground state leading to reabsorption limited power scaling [1]. To overcome this issue, the material has to be cooled to cryogenic temperatures, where four-level operation is accomplished. The monoclinic potassium lutetium double tungstate crystal, KLu(WO 4 ) 2 , considered here exhibits favourable spectroscopic properties when doped with Yb3+, characterized by large absorption and stimulated-emission cross sections and attractive thermo-optic properties for certain “athermal” crystal cuts (e.g., along the Ng-axis). It is very suitable for moderate power levels as demonstrated with Yb3+ and Tm3+ doping at RT [2]. In this work, we studied the continuous-wave laser characteristics of Yb:KLu(WO 4 ) 2 (Yb:KLuW) at cryogenic temperatures pumped by a VBG-stabilized fiber coupled diode laser at 981 nm.

Continuous wave (CW) laser performances of 1 at.% Yb:Lu2O3 sesquioxide ceramic medium were studied under various cryogenic temperatures. Two different fiber coupled diode pump sources, one emitting around 975.7 nm volume Bragg grating (VBG) stabilized and another around 940 nm were used for comparison. Under the pump at 975.7 nm and 100 K cryogenic temperature, the laser yielded CW output power of 11.24 W for 20.3 W incident pump power, corresponding to an overall optical-to optical efficiency of 55%; the slope efficiency was 59%. For operation at room temperature, the output power was limited to 4.44 W whereas the slope efficiency was 27.5%. Optimum operation under 940 nm pump was obtained at 80 K. Under 940 nm pumping, Yb:Lu2O3 medium generated a CW output power of 3 W for 20 W; the slope efficiency was around 17%. The passive Q-switch operation was investigated with Cr4+:YAG saturable absorber (SA) crystal, employing the pump at 975.7 nm. Laser pulses with an energy of 0.35 mJ and a pulse duration of 116 ns at 26.1 kHz repetition rate were recorded with a Cr4+:YAG SA having 85% initial transmission.

For the first time, CaMoO4: xEu3+ (x = 0.02, 0.04, 0.06, 0.08, 0.1) red phosphor nanoparticles were synthesized using the simple mechanochemically assisted solid state meta-thesis (SSM) reaction method and the luminescence properties as a function of Eu3+ ion concentration was investigated. The characteristics of the phosphor materials were analyzed using X-ray diffraction, fourier transform infrared spectroscopy, photoluminescence (PL) and diffuse reflectance spectroscopy. For 8 mol% of Eu3+ concentration, the phosphor shows an intensified excitation peak at 392 nm indicating a strong absorption. The PL emission spectra of CaMoO4: Eu3+ phosphors showed an intense peak at 615 nm (red) which corresponds to 5D0 → 7F2 transition of Eu3+. The optimal Eu3+ concentration in CaMoO4 phosphors for enhanced red emission occurs for 8 mol% and above this concentration, the emission intensity decreases due to quenching effect. The CIE colour coordinates of the CaMoO4: 0.08Eu3+ red phosphor coincide very well with the standard values of NTSC. The red emission intensity of the SSM prepared CaMoO4: 0.08Eu3+ red phosphor is 4.7 times greater than that of the commercial Y2O2S: Eu3+ red phosphor and 1.6 times more than the same phosphor prepared by the solid state reaction method.

In the later part of the twentieth century, classic cathode ray tubes (CRTs) are replaced by flat panel displays (FPDs) with a thinner, smaller size and with a significant reduction in power consumption. Such displays are currently used in several applications including mobile phones, laptops, and televisions. Among other FPDs, electroluminescent displays perform better than its counterparts such as liquid crystal, field emission, and plasma displays. Electroluminescent (EL) display is a common term for devices such as light-emitting diodes (LEDs), powder phosphor devices, thin film, and thick dielectric electroluminescent devices. Thin film EL devices (TFEL) show advantages such as quick response, high resolution, wide viewing angles and wide operating temperatures and so on. TFEL displays are all solid state and based on electroluminescence in which luminescent material gives light under high electric field.

We study cryogenic laser operation of an Yb-doped KLu(WO4)2 crystal pumped with a volume Bragg grating (VBG) stabilized diode laser at 981 nm. In the continuous wave laser regime, a maximum output power of 4.31 W is achieved at 80 K with a slope efficiency of 44.0% with respect to the incident pump power. Using a 85% initial transmission Cr:YAG crystal for passive Q-switching, an average output power of 2.11 W is achieved at 100 K for a repetition rate of 19 kHz. The pulse energy, pulse duration and peak power amount to 111 µJ, 231 ns and 0.48 kW, respectively.