Waveguide lasers have the advantages of miniature and compact structure and have broad application prospects in photonic integration and on–chip laboratories. The development of femtosecond laser direct–writing technology makes the processing of transparent materials more flexible and controllable. This paper mainly introduces a waveguide laser based on femtosecond laser direct–writing technology. Firstly, the applications of femtosecond laser direct–writing technology in an optical waveguide are introduced, including the principles of femtosecond laser direct–writing technology, common optical wave scanning methods, and types of optical waveguides. After that, we summarize the development of a waveguide continuous–wave laser, a Q–switched laser and a mode–locked laser from visible to mid–infrared wavebands and analyze some new representative work. Finally, we explain the difficulty of compensating for dispersion in pulse waveguide lasers and summarize some new ideas that have been proposed to solve the problem.

The number of electric vehicles is expected to increase significantly, which will affect the operation of future power systems. This study analyzes electric vehicle (EV) charging station data from residential (domestic) and commercial (public) charging stations throughout the entire annual cycle to extract the daily, weekly and seasonal loading patterns. A clear distinction has been established between the residential vs. commercial and slow vs. fast EV load profiles based on actual measurement data. The EV loading profiles have been overlaid on a distribution network loading profile to demonstrate the impact of widespread EV charging stations on the electricity network. The optimal power flow solution with and without the EV load profile have been presented. This study will present realistic future power system operational scenarios with widespread EV charging stations highlighting their impact on future power system voltage profile.

We demonstrate a self-starting high-energy erbium-doped soliton fiber laser by utilizing a spatial alignment structure (SAS). The saturable absorption (SA) effect of the SAS is based on the nonlinear coupling efficiency variation. Stable solitons can exist in the 400 mW-1.5 W pump power range. The center wavelength, pulse duration, and repetition rate of the output pulse are 1560.9 nm, 2.75 ps, and 3.9 MHz, respectively. The maximum single pulse energy of 8.67 nJ is obtained by changing the output coupler position, and the pulse energy is almost entirely concentrated in the soliton. Adjusting the alignment condition of SAS can change its SA characteristics, and act as an adjustable attenuator to control the net loss in the cavity. A tunable center wavelength of the soliton pulse, ranging from 1557.4 nm to 1561.2 nm, can be achieved by simply adjusting the mount of collimator. Various types of soliton dynamics processes, including single and double soliton pulse generation, pulsating soliton state with broadened sidebands, and high-order soliton spectrum evolution, have been observed in the experiment. This mode-locking technology based on a SAS opens a promising way for high-energy ultrafast laser.

In this paper, we report the use of femtosecond radially polarized vortex laser with MHz repetition rate for direct writing of cladding waveguides (WGs) and realization of waveguide laser oscillations in ytterbium‐doped calcium fluoride crystal. The negative refractive index modification in Yb:CaF ₂ crystal is fabricated by the homemade all‐fiber laser amplifier. At 976 nm pump wavelength, these Yb:CaF ₂ WGs can achieve continuous‐wave (CW) laser oscillation. The length of resonant cavity is 4 mm, and the minimum laser threshold is 116 mW, corresponding to the propagation loss of 0.85 dB/cm, the center wavelength of 1045.2 nm, and the maximum output power of 91 mW. In addition, a saturable absorber mirror (SAM) was prepared by depositing ReS _0.8 Se _1.2 on the reflective surface of a dichroic mirror to realize Q‐switched waveguide laser output. The output Q‐switched pulses with a tunable repetition rate in the range of 125–692.5 kHz, and the shortest pulse duration is 513 ns.

Multimode nonlinear dynamics in spatiotemporal mode-locked (STML) fiber lasers enable exploration of what we believe to be novel solitary waves. However, complex intermodal coupling in multimode fibers prevents precise control over the output parameters of multimode solitons (e.g., mode component and center wavelength), limiting their applications in fiber amplifiers and optical communications. Additionally, vector soliton dynamics have been overlooked due to polarization-dependent saturable absorbers (SAs) in prior STML systems, many unique nonlinear dynamics remain inadequately explained. This work presents a method to customize the output parameters of STML pulses by a spatial alignment structure (SAS). This polarization-independent SAS functions as an SA, spatial filter, and attenuator. Adjusting the SAS enables controllable multimode soliton characteristics and diverse STML dynamics, including soliton rain, tri-color solitons (TCS), and ultra-broad bandwidth spectrum (UBS) pulses (28 nm bandwidth, 94 fs duration) within the same cavity. Experimental results reveal the critical role of vector soliton dynamics in generating parametric sidebands and various STML pulses. This work demonstrates, to our knowledge, the first multimode vector conventional solitons and achieves the broadest bandwidth/shortest pulse duration in 1.5 μm STML lasers. Further research into multifunctional SAS and multimode vector soliton dynamics may uncover what are believed to be new spatiotemporal nonlinear effects, enabling compact, cost-effective STML fiber lasers with on-demand outputs.