This second edition of the Manual of Aesthetic Surgery, in a single-volume format, has been extensively revised to include a variety of new and interesting techniques. The result is a comprehensive ...book that clearly describes and depicts procedures currently used in aesthetic plastic surgery, with the aid of unsurpassed instructive drawings and high-quality pre- and postoperative photographs. Adjuvant treatments have been brought up to date to encompass the most recent developments. Great importance is attached to the fact that no alloplastic materials are used, but only biological implants, such as collagen, hyaluronic acid, polylactic acid, and autologous fat. All of the important aspects of chemical and laser peeling are presented, with guidance on what is useful and what is not. The section on cosmetic facial surgery includes an excellent new simple method of mini lift (M-Lift) that can be performed under local anesthesia in patients aged 40 and over. Similarly, the section on abdominoplasty presents a new mini abdomen procedure, an elegant and safe method that avoids repositioning of the navel and is ideal following pregnancies and in patients who are only moderately overweight or have slightly slack abdominal skin. Other novel techniques include a so-called de-epithelializing method that permits optimal anatomical positioning of the gluteal folds during a buttock lift and liposuction using a sophisticated Micro-Air system that avoids dimples and hematoma, eases convalescence, and is performed under local anesthesia. This interdisciplinary handbook will prove invaluable to both medical students and more experienced practitioners. It identifies the most appropriate technique for each indication, highlights tips and tricks, identifies pitfalls, and explains complication management. The accompanying DVD, including additional new clips, will further assist the reader in mastering each technique.
As a new solution‐processable laser material, carbon dots (CDs) offer advantages of non‐toxicity, low‐cost, and high‐stability, which are conducive to the sustainable development of miniaturized ...lasers. Full‐color CDs (FC‐CDs) with bright‐blue, green, yellow, red, deep‐red, and near‐infrared (NIR) fluorescence are prepared. Their photoluminescence emission ranges from 431 to 714 nm. The FC‐CDs show narrow full widths at half maximum in the range of 44–76 nm, with concurrent high radiative transition rates (KR) of 0.54–1.74 × 108 s−1; their performance is comparable to that of organic laser dyes, indicating their good gain potential for lasers. Laser pumping of the FC‐CDs gives laser outputs at 467.3, 533.5, 577.4, 616.3, 653.5, and 705.1 nm, spanning from blue to NIR region, and covering 140% of the NTSC color gamut. The FC‐CDs show high Q‐factors (2000–5500), appreciable gain coefficients (9–21.5 cm−1), and better stability (≈100%@4–7 h) than commercial laser dyes. These excellent properties make them suitable for high‐quality, colorful, speckle‐free laser imaging and dynamic holographic display. The findings will be helpful in promoting the practical applications and development of solution‐processable CD‐based lasers.
Tunable lasers span 238 nm across from blue to near‐infrared region are realized from full‐color carbon dots (FC‐CDs) in a mirrorless system. The lasers of the FC‐CDs show high Q‐factors, considerable gain coefficients, and better stability than common commercial organic dyes. Finally, high‐quality, colorful speckle‐free laser imaging and dynamic holographic display are successfully demonstrated using these lasers as light sources.
In this letter, we propose and demonstrate a tunable in-series distributed feedback (DFB) laser array, and the wavelength is continuously tuned with the assistance of the monolithically integrated ...thin-film heater. Compared with an in-parallel laser array with an optical combiner, the proposed in-series DFB laser array avoids significant power loss resulting from the optical combiner. The three-section structure is utilized to suppress the grating crosstalk among the in-series laser array and guarantees single-mode stabilities. Besides, the reconstruction-equivalent-chirp technique is utilized to simplify grating fabrication and enhance the precise control of the grating phase. Four lasers with wavelength spacings of 2.4 nm are integrated into the in-series laser array and the Ti/Pt thin film heaters are monolithically integrated near the waveguides of each laser unit. The wavelength of the proposed structure is coarsely tuned by selecting the working laser and finely tuned by adjusting the injection current to the laser unit and the thin-film heaters. 9.6 nm continuous wavelength tuning range and fast wavelength tuning are obtained for the proposed in-series laser array without adjusting the temperature of the thermal-electric cooler (TEC). The proposed structure provides a solution for the wavelength tunable laser, which is promised to be used in the dense wavelength division multiplexing (DWDM) systems.
Tandem pumping is a promising technique for gaining higher power from ytterbium-doped fiber (YDF) lasers. However, the characteristics of tandem pumped laser light, especially their variation with ...the lasing wavelengths, were not thoroughly investigated. We investigated the characteristics with the first 1018-nm tandem-pumped high-power tunable YDF laser. The 1018-nm tandem pumping was not applicable in tunable fiber lasers before because its much-lower absorption requires compensation of long YDFs, which enhances destructive nonlinear effects as a barrel effect for tuning wavelengths. Here, the setup used a fiber ring-cavity as seed, which was much more cost-effective than conventional setups, and only three stages of amplification, of which the last stage was unidirectional tandem-pumped. By deliberate system design, it gained over 1-kW output powers at wavelengths tuning from 1060-1090 nm with ∼100-pm 3 dB linewidths and 79.4%∼85.6% slope efficiencies. Amplified spontaneous emissions (ASE) and stimulated Brillouin scattering (SBS) caused no limits for further scaling powers. Variations of spectra and beam qualities of the outputs with the tuning wavelengths were revealed in detail in the experiment. Drastically varying linewidths at ∼1062 and ∼1080 nm suggested complex evolution of the nonlinear effects with the pump light. This study offers not only an economic seed setup to high-power narrow-linewidth tunable fiber lasers, but detailed characteristics of laser amplified with 1018-nm pump in YDFs. The knowledge of the characteristics can usefully guide future design of high-performance tandem-pumped fiber lasers.
Objectives
The study aimed to improve the safety and accuracy of laser osteotomy (bone surgery) by integrating optical feedback systems with an Er:YAG laser. Optical feedback consists of a real‐time ...visual feedback system that monitors and controls the depth of laser‐induced cuts and a tissue sensor differentiating tissue types based on their chemical composition. The developed multimodal feedback systems demonstrated the potential to enhance the safety and accuracy of laser surgery.
Materials and Methods
The proposed method utilizes a laser‐induced breakdown spectroscopy (LIBS) system and long‐range Bessel‐like beam optical coherence tomography (OCT) for tissue‐specific laser surgery. The LIBS system detects tissue types by analyzing the plasma generated on the tissue by a nanosecond Nd:YAG laser, while OCT provides real‐time monitoring and control of the laser‐induced cut depth. The OCT system operates at a wavelength of 1288 ± 30 nm and has an A‐scan rate of 104.17 kHz, enabling accurate depth control. Optical shutters are used to facilitate the integration of these multimodal feedback systems.
Results
The proposed system was tested on five specimens of pig femur bone to evaluate its functionality. Tissue differentiation and visual depth feedback were used to achieve high precision both on the surface and in‐depth. The results showed successful real‐time tissue differentiation and visualization without any visible thermal damage or carbonization. The accuracy of the tissue differentiation was evaluated, with a mean absolute error of 330.4 μm and a standard deviation of ±248.9 μm, indicating that bone ablation was typically stopped before reaching the bone marrow. The depth control of the laser cut had a mean accuracy of 65.9 μm with a standard deviation of ±45 μm, demonstrating the system's ability to achieve the pre‐planned cutting depth.
Conclusion
The integrated approach of combining an ablative laser, visual feedback (OCT), and tissue sensor (LIBS) has significant potential for enhancing minimally invasive surgery and warrants further investigation and development.
•A neodymium-doped yttrium aluminum garnet (Nd:YAG) pulsed laser system was developed and employed to drill holes in a 3-mm-thick optical-grade acrylic (PMMA) plates.•A laser energy density range of ...141.26–275.93 J/cm2 is suitable and can obtain an acceptable heat-affected zone.•The Nd:YAG pulsed laser can produce laser plasma that can achieve up to 50% larger hole diameters because of the cavity gap produced.•Various entrance and exit hole shapes can be obtained by changing the working positions of the acrylic (PMMA) plates.
Laser material processing (LMP) is used to replace traditional material processing techniques, such as material cutting, thin plate drilling, and surface processing. When a high-energy laser is projected onto a material, the temperature of the material increases rapidly, changing the characteristics of the material and making the material on the surface vaporize and peel off instantly. In this study, we developed a laser system using a Quantel Brilliant neodymium-doped yttrium aluminum garnet (Nd:YAG) with a wavelength of 1064 nm laser a pulse width of 5–6 ns, a beam diameter of the 6 mm, and 10 repetition rate (Hz) on the energy stability is within 5.60%, an F-theta lens is used to obtain a focused laser beam with a diameter of 0.2 mm. The developed system was employed to drill holes in a 3-mm-thick optical-grade acrylic polymethyl methacrylate (PMMA) plate with high optical density and 7 + safe windows. A laser-safe, flat-window, visible-light-transmitting (VLT) sample was used, and the material to be drilled was a PMMA plate. The laser beam must be focused on the center of the F-theta lens and must be aligned with the distance between the F-theta lens and the linear stage. The working distance was set to 300 mm. Furthermore, the diameter was adjusted to obtain the laser plasma effect; that is, the working distance was fixed. First, the characteristics of the laser plasma and the ability of the laser to penetrate optical-grade acrylic (PMMA) plates samples were studied. By changing the lifting position of the vertical axis and varying the working distance of the acrylic (PMMA) plates, the laser beam was targeted at different positions on the acrylic (PMMA) plates. To determine the optimal parameters for the drilling process, a pulsed laser output of 174.7 mJ/pulse (3000 pulses in 5 min) was focused on the hole. Results showed that the energy was 522.98 J/cm2; a laser energy density of 141.26–275.93 J/cm2 resulted in an acceptable heat-affected zone. The Nd:YAG pulsed laser can produce laser plasma that can increase the hole diameter by up to 50% because of the produced cavity gap. Various exit and entrance hole shapes can be achieved and thus employed for different applications, such as laser beam cutting.
For decades, researchers have been interested in developing efficient rare-earth-doped laser sources using dual-wavelength pumping. However, dual-wavelength pumping of rare-earth-doped lasers and ...amplifiers are currently restricted to pump wavelengths longer than the visible. Extending the use of dual-wavelength pumping for directly diode-pumped rare-earth-doped lasers is of great importance for both academic and practical purposes. We have developed the first blue dual-wavelength pumping of Holmium-doped ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (Ho:ZBLAN) fiber lasers operating at 75X nm. A dual-wavelength pumping method was proposed by pumping two separate wavelengths of 449 and 442 nm into a Ho:ZBLAN fiber to populate the upper laser state 5 F 4 + 5 S 2 and depopulate the lower laser state 5 I 7 , respectively. The influence of the 449 and/or 442 nm pumping schemes on the efficiency and threshold of the 75X nm laser was studied by varying the active fiber length. For dual-wavelength pumping with blue laser diodes, a shorter fiber and a lower 449 nm pump power are favoured. Our approach expands the applicability of dual-wavelength pumping to visible laser systems with energy-level structures consisting of long-lived lower-level bottlenecks.
A novel 0.98 μm and 1.15 μm dual-wavelength pumping scheme for cascaded mid-infrared Er-doped ZBLAN fiber laser at 3.44 μm and 2.78 μm is proposed and analyzed by a detailed theoretical model. In our ...pumping scheme, the 4 I 13/2 level (the lower level of 2.78 μm laser), which is taken as a virtual ground state, is first populated by 976 nm pump and 2.78 μm transition. The 1150 nm virtual ground state absorption (VGSA), corresponding to 4 I 13/2 → 4 F 9/2 transition, excites the Er ions accumulated in 4 I 13/2 level to 4 F 9/2 level (the upper level of 3.44 μm laser), emptying the 4 I 13/2 level as well as providing positive gain for 3.44 μm laser. Followed by the 3.44 μm laser transition, the Er ions would rapidly decay to 4 I 11/2 level (the upper level of 2.78 μm laser) via nonradiative transition, realizing the re-population of 4 I 11/2 level and enhancing the 2.78 μm laser gain. Hence, a cycling of Er ions between 4 I 13/2 level and 4 F 9/2 level, which includes both 2.78 μm and 3.44 μm laser transitions, is realized via the 4 I 13/2 → 4 F 9/2 VGSA. An interesting point in our proposed pumping scheme is that both the 2.78 μm and 3.44 μm laser power are dominantly contributed by the VGSA pump, while the main role of 976 nm pump is to provide initial population to sustain the ions cycling. By optimizing the wavelength of VGSA pump, dual-wavelength pump power ratio and laser cavity parameters, the overall optical efficiency of the two laser output power with respect to pump power could be improved to over 55%. This work provides a new insight on the cascaded mid-infrared fiber laser and also a promising pumping scheme for efficient 2.78 μm and 3.44 μm laser generation simultaneously from single Er-doped ZBLAN fiber.
This paper describes the design, fabrication, and record performance of a new class of ultra-wideband wavelength tuning, ultra-low noise semiconductor laser, the Integrated Coherent Tunable Laser ...(ICTL). The ICTL device is designed for, and fabricated in, a CMOS foundry based Silicon Photonics platform, utilizing heterogeneous integration of III-V material to create the integrated gain section of the laser-enabling high-volume mass-market manufacturing at low cost and with high reliability. The ICTL incorporates three or more ultra-low loss micro-ring resonators, with large ring size, in a Sagnac loop reflector geometry, creating exceptional laser reflector performance, plus an extended laser cavity length that enables highly-coherent output; ultra-low linewidth and phase noise. This paper describes record integrated laser performance; 118 nm wavelength tuning, covering S-, C- and L-bands, with Lorentzian linewidth <100 Hz, and with excellent relative intensity noise (RIN) of ≤ −155 dBc/Hz. The remarkable performance of the ICTL device, coupled with the high volume/low cost capability of the Silicon Photonics platform enables next-generation applications including ultra-wideband WDM transmission systems, fiber-optic and medical-wearable sensing systems, and automotive FMCW LiDAR systems utilizing wavelength scanning.
Advanced applications in optical frequency metrology demand improved tunable lasers with high coherence. Herein, a tunable single-frequency fiber laser based on the longitude-purification induced by ...the distributed feedback has been demonstrated. The key device in the proposed laser structure is a distributed self-injection feedback structure (DSIFS) which function as a mode selector to have a robust frequency-domain mode suppression and wavelength adaptability. Our work is distinctly focused on the theoretical analysis of the formation process of single-longitudinal-mode (SLM) laser output and the wavelength adaptive characteristics in the DSIFS. In this experiment, the side mode suppression of the resonant longitudinal modes can be achieved in a fiber ring laser without any accurate control of the main cavity. The fiber laser obtained a compressed laser linewidth of 855 Hz, enhanced side mode suppression ratio (SMSR) of ∼67 dB, and frequency noise suppression of 40 dB. Furthermore, the fiber laser can be tuned over the entire flat gain region. The measured output power, wavelength and SMSR variations of the proposed laser over a long-term observation are less than 0.034 mW, 0.028 nm and 2.53 dB, respectively. In addition, the SLM operation of the laser can also be obtained at different pump power for every wavelength channel. Moreover, this method is applicable to any other gain-type lasers, indicating that the longitude-purification mechanism has a broad application prospect in other highly coherent tunable lasers.
PDF
