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Cafe-au-lait macules (CALMs) affect the appearance of patients and can result in serious psychological problems. Successful treatments without adverse effects remain challenging. We designed a prospective, randomized, controlled, evaluator-blinded trial on 40 pediatric patients to compare the efficacy between a low-fluence 1064-nm Q-switched Nd:YAG laser and a Q-switched Nd:YAG 532-nm laser for the treatment of solitary CALMs in children. We randomly assigned participants into 2 groups. We treated those in the first group with 3 sessions of 532-nm QS laser at 1-month intervals, and those in the second group with 6 sessions of 1064-nm LFQS laser at 2-week intervals. We found no significant differences in treatment efficacy (p = 0.14). The 1064-nm laser group referred significantly less pain than the 532-nm laser group (p = 0.0001). Side effects were detected in 5 patients in the 532-nm laser group. The difference of the side effects was statistically significant (p = 0.04). Two patients in 532-nm laser group were recurred and none in 1064-nm laser group. On a univariate logistic regression analysis, lesions with brown color, small size, and irregular edges were significantly associated with better outcomes (> 50% clearance). Multivariate logistic regression analysis found that brown lesions and lesions with irregular edges had higher odds of getting > 50% clearance (p < 0.05). In conclusion, the 1064-nm LFQS laser produced fewer side effects, less pain, and shorter recovery time than the 532-nm laser. Irregular-bordered, smaller, brown lesions improved better than smooth-bordered, larger, light brown lesions. Moreover, the 1064-nm laser may be a better choice for treating large size CALMs. However, no significant differences were found in terms of the treatment efficacy and recurrence.

The first book on this hot topic includes such major research areas as printed electronics, sensors, biomaterials and 3D cell printing.Well-structured and with a strong focus on applications, the text is divided in three sections with the first describing the fundamentals of laser transfer.

Generation of two identical ns laser pulses spaced by a single ?s time interval by means of sequential switching of the output mirror transmittance in a diode-pumped Nd:YAG laser is reported, to our knowledge, for the first time. The theoretical study of the process of transmission losses switching is developed. This analysis confirms the possibility of generation of two identical Q-switched laser pulses with 100% efficiency with respect to the referenced single pulse energy. The detailed characterization of the laser in free-running, single and double Q-switching regimes is presented. The laser can be applied in different branches of metrology as PIV, LIBS or holographic interferometry.

Optical vortex arrays are characterized by specific orbital angular momentums, and they have important applications in optical trapping and manipulation, optical communications, secure communications, and high-security information processing. Despite widespread research on optical vortex arrays, the 2 μm wavelength range remains underexplored. Pulsed lasers at 2 μm are vital in laser medicine, sensing, communications, and nonlinear optic applications. The need for 2 μm-pulsed structured optical vortices, combining the advantages of this wavelength range and optical vortex arrays, is evident. Therefore, using just three elements in the cavity, we demonstrate a compact self-Q-switched Tm:YALO3 vortex laser by utilizing the self-modulation effect of a laser crystal and a defect spot mirror. By tuning the position of the defect spot and the output coupler, the resonator delivers optical vortex arrays with phase singularities ranging from 1 to 4. The narrowest pulse widths of the TEM00 LG0,−1, two-, three-, and four-vortex arrays are 543, 1266, 1281, 2379, and 1615 ns, respectively. All the vortex arrays in our study have relatively high-power outputs, slope efficiencies, and single-pulse energies. This work paves the way for a 2 μm-pulsed structured light source that has potential applications in optical trapping and manipulation, free-space optical communications, and laser medicine.

Nevus of Ota is cosmetically burdensome and often prompts patients to seek treatment. Lasers are commonly used in removing these lesions; however, no systemic analysis has been conducted to support a gold standard laser. To conduct a meta-analysis of the efficacy and safety of Q-switched Nd:YAG lasers (QSNL), Q-switched ruby lasers (QSRL), Q-switched alexandrite lasers (QSAL), and picosecond alexandrite lasers (PSAL) in removing nevus of Ota. Inclusion criteria were nevus of Ota patients treated with QSNL, QSRL, QSAL, or PSAL and documentation of percent clearance and the rate of at least one adverse event. Articles in English, Chinese, or Japanese were included. The prespecified outcome measures were efficacy (percent clearance) and safety (rates of hyperpigmentation, hypopigmentation, scarring, and recurrence). The review included 57 studies and 13,417 patients. The pooled success rate was 64% for QSNL (95% CI 52–76%), 54% for QSRL (95% CI 39–69%), 58% for QSAL (95% CI 44–72%), and 100% for PSAL (95% CI 98–102%). The pooled adverse event rate was 5% for QSNL (95% CI 4–6%), 14% for QSRL (95% CI 9–19%), 9% for QSAL (95% CI 6–12%), and 44% (95% CI 31–57%) for PSAL. QSNL has the most evidence for effectively and safely treating nevus of Ota. PSAL potentially has a superior efficacy; however, further studies are needed to elucidate its side effect profile when treating nevus of Ota.

Conventional optoacoustic microscopy (OAM) instruments have at their core a nanosecond pulse duration laser. If lasers with a shorter pulse duration are used, broader, higher frequency ultrasound waves are expected to be generated and as a result, the axial resolution of the instrument is improved. Here, we exploit the advantage offered by a picosecond duration pulse laser to enhance the axial resolution of an OAM instrument. In comparison to an instrument equipped with a 2-ns pulse duration laser, an improvement in the axial resolution of 50% is experimentally demonstrated by using excitation pulses of only 85 ps. To illustrate the capability of the instrument to generate high-quality optoacoustic images, en-face, in-vivo images of the brain of Xenopus laevis tadpole are presented with a lateral resolution of 3.8  μm throughout the entire axial imaging range.

Background Lasers and other energy‐based devices are increasingly becoming popular in aesthetic practice. Many centers employ doctors or technicians to perform these procedures where treating doctor and operating doctor may be different. Hence the need for standard operative protocols, to be followed while performing these procedures to avoid mistakes, complications and to get optimum results. In the current review article, group of doctors who have worked with these energy‐based devices over many years worked together and suggested the protocols to be followed for the most commonly used energy‐based procedures. Aim To provide Standard operating protocols for the operator and staff to ensure, efficacy, safety, for the patient and for the devices. Methods The following protocols have been drafted based on the best practices followed by the authors in their clinics and reflect their consensus opinion. The objective is to provide operating protocols in a standard format, which can be of use by practicing dermatologists and their staff. The protocols include both general guidelines for the laser room and specific protocols for different machines. The draft follows the following schema: General instructions for all the energy‐based devices. Specific protocols for different devices: Laser hair removal, fractional lasers, Q‐switched lasers, fractional microneedling radiofrequency and cryolipolysis. Conclusions The protocols proposed help to maintain the uniformity and avoid complications. However, these instructions are generalized and not machine or lesion specific. There may be variations in the protocols depending on the treatment lesion and treating doctor as well as machine.

Ultrafast lasers allow high-precision imaging and manipulation for biological and medical applications. Nonlinear optical microscopy has provided researchers with unique possibilities of three-dimensional imaging of biological cells and tissues. Nonlinear optical imaging technique is a rapidly emerging research area with widespread fundamental research and clinical applications. Nonlinear optical imaging allows both structural and functional imaging with cellular level resolution imaging in biological systems. The introduction of endogenous or exogenous probes can selectively enhance contrast for molecular targets in a living cell as well as supply functional information on processes. With the aim to control nonlinear optical processes and to obtain functional images, nonlinear optical processes can be controlled by photo-controlled probes and/or parameters of ultrafast laser pulses, such as time, space, polarization, and phase. This book gives an overview of the nonlinear optical process by ultrafast laser pulses and explains how the basics of nonlinear optical microscopy led to the most advanced techniques of photo-controlled nonlinear optical microscopy.

A diode-pumped Q-switched mode-locked Nd:YVO4 laser via a positive cascaded second-order Kerr lens using periodically poled MgO:SLT at 1064 nm was reported. Q-switched mode-locking performances, including pulse duration, output power, and bandwidth, were studied under different pump conditions. Under 28 W quasi-CW (QCW) diode pump peak power, the measured mode-locked pulse train, Q-switched repetition rate, and Q-switched pulse duration were 18 ps, 300 kHz, and 50 ns, respectively. The highest peak power of a single pulse near the maximum of the Q-switched envelope was greater than 150 kW.

In this work, we successfully fabricated a transmissive saturable absorber (SA) with Ti2CTx MXene using the spin-coating method. By inserting the Ti2CTx saturable absorber into the diode-pumped solid-state (DPSS) Nd:YAG laser, a stable passively Q-switched operation was obtained near 1.06 μm. At a pump power of 4.5 W, we obtained the shortest pulse duration of 163 ns with a repetition rate of 260 kHz. The corresponding single pulse energy and peak pulse power were 3.638 μJ and 22.3 W, respectively. The slope efficiency and the optical conversion efficiency of the laser were 21% and 25.5%, respectively. To the best of our knowledge, this is the first time that Ti2CTx was used in the passively Q-switched solid-state lasers. This work demonstrates that Ti2CTx can be a promising saturable absorber for solid-state laser pulse generation.