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A high-power $588\mathrm{nm}$ light produced by an intracavity frequency-doubling acousto-optic Q-switched self-frequency Raman laser is reported. A $20\text{-}\mathrm{mm}$-long $\mathrm{Y}\mathrm{V}{\mathrm{O}}_4∕\mathrm{Nd}:\mathrm{Y}\mathrm{V}{\mathrm{O}}_4$ composite crystal and a $15\text{-}\mathrm{mm}$-long $\mathrm{Li}{\mathrm{B}}_3{\mathrm{O}}_5$ (LBO) with noncritical phase-matching ($\theta =90°$, $\varphi =0°$) cut were adopted for efficient self-Raman laser operation and second-harmonic generation, respectively. By the optimizing the focus position of incident pump light and Q-switch repetition rate, yellow light with $5.7\mathrm{W}$ average power was generated under the pump power of $23.5\mathrm{W}$, corresponding to the overall diode-yellow conversion efficiency of 24.2% and slope efficiency of 32%. The pulse width is about $16\mathrm{ns}$, and the pulse energy is up to $95\mu \mathrm{J}$.

Intra-cavity frequency doubling with 589 nm emission from a compact c-cut Nd:YVO₄ crystal self-Raman laser was investigated. A 15-cm-length LBO with non-critical phase-matching cut (θ = 90°, ϕ = 0°) was used for efficient second-harmonic generation. At a pump power of 16.2 W and a pulse repetition frequency of 40 kHz, output power up to 2.15 W was achieved with a pulse width of 16 ns and a conversion efficiency of 13.3% with respect to the diode pump power. The center wavelength was measured to be 589.17 nm with a Half-Maximum-Full-Width of 0.2 nm, which was well in accordance with the sodium D₂ resonance radiation.

Due to the increasing market demand for graphene-based devices, van der Waals heterostructures based on 2D materials have increased rapidly worldwide during the last decade. Graphene-based applications are inadequate in some electronic devices such as field-effect transistors (FETs) and solar cells devices due to its intrinsic zero bandgap and complex mechanistic approach in related chemistry. Thus, it is highly desired to fill the gap and devote efforts to explore other 2D materials further, especially bi- and tri-elemental 2D materials, such as layered metal chalcogenides (LMDCs), metal oxides, and hexagonal boron nitride (hBN). During the past few years, a different research group contributed to improving the quality and performance of the mentioned 2D materials. Still, due to some deficiencies such as low conductivity and poor bandgap, there is a need to develop and investigate alternative materials. Recently, MXenes, which are compounds obtained due to the chemical delamination of quaternary or (ternary) layered nitrides or carbides, have been found as a great class of 2D elemental materials. The complex bonding in the MXene family (a mixture of metallic and covalent bonds) and other characteristics such as atomic stacking, electronic structures, surface terminal groups, and different synthetic routes are responsible for their unique properties such as hydrophilicity and metallicity, and they are predicted to have high elastic moduli in a single compound. On behalf of the rich chemistry and unique morphologies, MXene derivatives have delivered efficient sensors, energy storage materials, catalysts, and water purification materials. Although there is a great demand for MXene-based derivatives, there is further demand for their improvement such as the long-term stability, large scale production, as well as deposition and surface roughness, which create hurdles in their commercialization. Titanium-based MXene (Ti₃C₂Tx and Ti₂CTx) heterostructures with other 2D nanomaterials are highly desired to solve the surface roughness problems and long-term stability as well as an alternative to overcome the deficiency of the scalable production of MXenes. The existence of different active functionalities (–O, –OH, –F, etc.) on the surface of Ti₃C₂Tx and Ti₂CTx can be helpful for interacting with other 2D layered materials in the presence of solvents to fabricate heterostructures after using various deposition techniques such as spin coating, dip coating, and drop-casting for practical device fabrication processes. In the presence of weak interaction between the host (MXene derivatives) and guest (other nanostructures 2D materials), the intrinsic characteristics of both can be largely preserved for efficient energy storage applications. In this paper, we present a comprehensive literature library of the various strategies of 2D titanium-based MXenes such as Ti₃C₂Tx and Ti₂CTx for the fabrication of their heterostructures with 2D materials using various deposition techniques and the application of the resultant structures in the fields of optoelectronics, catalysis, and energy storage devices.

An intra-cavity optical parametric oscillator (OPO) emitting at 1.7 μm derived by $\mathrm{Nd}\text{:}{\mathrm{YVO}}_4$ self-Raman laser is demonstrated in this Letter, with a ${\mathrm{KTiOAsO}}_4$ (KTA) crystal used as nonlinear optical crystal. A laser diode end-pumped acousto-optic $Q$-switched $\mathrm{Nd}\text{:}{\mathrm{YVO}}_4$ self-Raman laser at 1176 nm was employed as the pump source. At an incident pump power of 12.1 W and a pulse repetition frequency of 60 kHz, average output power up to 1.2 W signal light at 1742 nm was obtained, with diode-to-signal conversion efficiency of 10%. The pulse width was about 11 ns and spectral line width was less than 0.5 nm for the signal light. The results show that compact intra-cavity KTA-OPO derived by $\mathrm{Nd}\text{:}{\mathrm{YVO}}_4$ self-Raman laser is an efficient method for 1.7 μm waveband laser generation, with potential applications in biological imaging, laser therapy, special materials processing, etc.