Diode Lasers Research Papers - Academia.edu (original) (raw)

Lasers are a relatively new addition to the orthodontist's armamentarium. This article reviews the fundamental basic science of available soft-tissue lasers, with an emphasis on diode lasers, and discusses various adjunct applications of the diode laser for soft-tissue orthodontic procedures. Diode lasers function by cutting with an initiated hot tip and produce minimal to no interaction with healthy dental hard tissue, making them suitable for soft-tissue procedures. The contact cutting mode provides enhanced bloodless site visibility and facility to perform delicate soft tissue procedures, which is important in areas with difficult access. Such adjunctive uses include laser gingivectomy to improve oral hygiene or bracket positioning, esthetic laser gingival recontouring, and laser exposure of superficially impacted teeth. Selected cases treated with a 940-nm indium-gallium-arsenide-phosphide (InGaAsP) diode laser will be presented.

- by Ali Borzabadi-Farahani
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- Diode Lasers

Ž . We report on frequency stabilization of a diode laser to the hyperfine components of the P 33 6-3 and R 127 11-5 transitions of molecular iodine at the He-Ne laser wavelength of 633 nm. Single frequency operation and wavelength control of the diode laser in a compact form is obtained by employing weak optical feedback from an integrated microlens. The diode laser driven by an ultra low noise current supply provides nearly shot noise limited detection. A relative frequency stability of 5 = 10 y12 is achieved at an integration time of 100 s. Harmonic distortion of the modulated output of the diode laser due to spurious optical feedback is considered to be the main effect limiting the day-to-day frequency reproducibility of 5 = 10 y11 . q 1998 Elsevier Science B.V. All rights reserved.

- by Hannu Talvitie
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- Laser Spectroscopy, Diode Lasers, Optical physics, Optical Metrology

LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Over the years, lasers have advanced imperceptibly in our day to day life from recording price of groceries to laser guided warfare. Lasers saw the light of day due to Ted Maiman in 1960 but it was not until 1980’s that lasers saw their use in dental clinical practice. This article reviews the uses of diode lasers in dentistry.

In this paper we study laser diode parameters in fiber optic communication system and we study the relationship between them. The capacity of optical communication systems is rising exponentially in order to follow the rapidly increasing demand for data traffic. Limitations due to dispersion and nonlinearity in the optical fiber become more stringent for higher bit rates.. In optical communication transmitters are light sources, receivers are light detectors and the channels are optical fibers. In optical communication the channel i.e., optical fiber plays an important role because it carries the data from transmitter to the receiver. Laser is a powerful source of light having extraordinary properties which are not found in the normal light sources like tungsten lamps, mercury lamps, etc..Laser surgery has also provided itself to be a preferred tool of operation over standard tools in a lot of the cases.

- by Mohit Anand
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- Optics, Optical Fiber Communications, ABC, Diode Lasers

二極體雷射又稱作軟組織雷射，因其擁有牙齦手術切割的能力，裝置尺寸小且費用相對較低，在部分臨床牙醫師之間已漸漸風行。軟組織雷射的防潮控制(moisture control)與止血(hemostasis)的能力，使臨床牙醫師切割牙齦組織、施行美觀性牙冠增長術(esthetic crown lengthening)、與降低牙齦溝(gingival troughing)等術式容易上手，讓臨床牙醫師們對於雷射手術技術的操作更容易熟悉。軟組織雷射在牙科領域中也漸漸被接受，他們有潛力在降低生物性副作用的情況下，完成贗復前牙齦處理。這篇文章強調了二極體雷射於上顎前牙的牙周-贗復技術中的使用。針對他們臨床優點的評估，討論其使用在美容牙科治療的好處。

Introduction: Neovascular glaucoma (NVG) is an aggressive glaucoma subtype of difficult management. Cyclodestructive procedures are a viable treatment option and diode laser ablation has been reported to be effective and safe. The purpose of this study was to evaluate the effectiveness and safety profile of diode laser cyclophotocoagulation in diabetic NVG.
Methods: Ambispective case-control study of 38 eyes (19 control group CG, 19 treatment group TG). Success was defined as intra-ocular pressure (IOP) <22mmHg or a 30% reduction from baseline. Intraocular pressure, number of anti-glaucoma drugs, visual acuity and pain were documented.
Results. Both groups were similar in age, sex and initial IOP. Follow-up time was 11 months (TG) and 7 months (CG). Cyclophotocoagulation was carried out in 19 eyes of TG (100J/session). IOP decreased from 38.7mmHg to 13mmHg in TG (p<0.001), vs. 42.6mmHg to 47.3mmHg in the CG (p=0.23). Success was achieved in 73.6% of the TG. Only 5 eyes (X%) developed hypotony (<5mmHg) post-treatment.
Conclusion. Diode laser cyclophotocoagulation is an effective IOP lowering procedure in diabetic NVG. Laser treatment energy per session should be lowered to 40-80J in order to reduce the risk of ocular hypotony.

- by Angelina EspinoBarros-Palau and +1
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- Diabetes Mellitus and Its Complications, Diode Lasers, Neovascular Glaucoma

Laser cladding is a very competitive alternative to traditional arc-based cladding methods, due to a much lower heat input. The technology can be used for cladding large surface areas and can also be expanded to applications like repair and additive manufacturing. Almost all types of laser can be used for cladding, but diode lasers offer many advantages thanks to their relatively low cost of purchase and operation.

- by Bernd Baufeld
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- Diode Lasers, Laser Cladding

Multilevel inverters have already gained high popularity among research teams as well as in production of high and medium-voltage applications for industrial purposes over the period of twenty years. Moreover, multilevel inverters are able to generate switched waveforms with reduced levels of harmonic sag compared to a conventional converter. Recent increased interest in multilevel inverters is due to their ability to generate high quality output waveforms at lower switching frequencies; the multilevel topology used in dynamic voltage restorer works towards the reduction of the total harmonic distortion counting all of the losses at the output end. This paper provides a new topology for the modulation in the multilevel inverter using switched capacitor. The self-balancing capability for the capacitor voltage and the SC connected in parallel so as to provide the voltage setup. The methodology presented works towards minimizing the THD by implementing the 9 level MLI and comparing the same to the other level in terms of distortion. The factors like cost are also considered in the design for which half bridge is being used.

- by IJRASET Publication
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- Topology, Modulation, Diode Lasers, Multilevel Inverter

Continuous-wave ultraviolet radiation has been generated by frequency doubling the output of a 15-mW, 634-nm diode laser with a rubidium dihydrogen phosphate (RDP) crystal inside an external resonant cavity. Singlefrequency operation (2 MHz linewidth) of the diode laser is obtained by employing weak optical feedback from a microlens. By using the resonant cavity, a power buildup factor of 60 is achieved and up to 30 µW of tunable ultraviolet radiation around the wavelength of 317 nm has been produced. PACS: 42.65.Ky; 42.55.Px Compact, reliable, and efficient ultraviolet (UV) lasers are essential for many applications ranging from optical data storage to spectroscopic analysis. Diode lasers would be almost ideal light sources for these applications, except that their available wavelength range covers only the red and infrared part of the spectrum. Generation of shorter wavelength radiation is, however, possible by frequency conversion in a nonlinear crystal. Previous demonstrations [1-3] have shown that efficient generation of continuous-wave UV radiation can be achieved by second-harmonic generation (SHG) of red diode lasers with a nonlinear crystal placed in a resonant cavity. Ultraviolet powers of 18 µW at 370 nm [1], 35 µW at 369 nm [2], and 260 µW at 344 nm have been reported. In related work, two successive resonant cavities have been used to quadruple the frequency of a high-power nearinfrared diode laser to generate 2.1 mW of UV radiation at 243 nm . Generation of UV radiation using quasi-phase matching (QPM) to enhance the conversion efficiency has also been demonstrated . Applying QPM in a periodically poled bulk crystal and a diode laser pump, Mizuuchi et al. reported UV power of 30 µW at 340 nm [6]. However, efficient generation of shorter wavelengths using QPM technique is presently limited by difficulties in poling dense (∼ 1 µm) first-order periods with high optical quality . * Corresponding author Our work is primarily motivated by the need for lasers in radiometric characterization of detectors in the biologically interesting solar UV band 300-320 nm . It should be noted that laser sources are not readily available in this narrow UV band. The importance of high-accuracy detector characterization near 300 nm has been emphasized by the increase of biologically harmful solar UV radiation due to depletion of stratospheric ozone. For this purpose a continuouswave laser with an output power of a few tens of microwatts is required. The recent development of 635-nm diode lasers has made frequency doubling to this UV band possible.

- by Hannu Talvitie
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- Nonlinear Optics, Diode Lasers, Ultraviolet, Optical physics

Acute exacerbations of pericoronitis is associated with debilitating symptoms, and requires urgent intervention. Mechanical debridement, operculectomy and antibiotic therapy are parts of established treatment protocol, however, associated with many limitations. This report highlights successful management of a case of pericoronal abscess around mandibular third molar in a 30-year-old female, with GaAlAs diode laser-assisted disinfection and operculectomy. Although infection was initially associated with lymphadenitis and fever, postoperaive period was symptom free, even without use of antibiotics. Due to many intraoperative and postoperative advantages and better patient acceptance, diode laser has become a preferred option for minor oral surgical procedures.

- by Farrukh Faraz and +2
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- Diode Lasers, Laser Tissue İnteractions : Dental Lasers, Pericoronitis
- by Dionisius Kristanto
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- Laser, Diode Lasers
- by Bernd Baufeld
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- Additive Manufacturing, Diode Lasers, Electron beam welding, Laser Cladding
- by Sebastian Saliba
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- Diode Lasers, Grating Feedback, Laser Stability, Laser Resonators

The aim of this study was to present a case report of surgical removal of hyperplasia in the oral cavity using diode laser
radiation and rehabilitation with a complete denture. Epulis fissuratum is a pseudotumor growth located over the soft tissue
of the vestibular sulcus caused by the chronic irritation from the poorly adapted dentures. The case discussed in the present
study reported with the massive fibrous mass (5x2x1 cm) with multiple folds located in the maxillary vestibular sulcus
extending bilaterally from canine to canine region. This massive lesion was excised using diode laser and new complete
dentures with proper peripheral extensions were fabricated and delivered to the patient. Patient was kept on regular follow
up and clinical examination revealed normal vestibular mucosa and functionally sufficient prosthesis.
Keywords: Epulis Fissuratum; Diode Laser; Hyperplastic; Ill Fitting Dentures.

A frenum is a soft tissue attachment of the labial, buccal and lingual mucosa to the jaw bones. Abnormalities in development of this soft tissue fold may present as a very short lingual frenum limiting the mobility of the tongue. This condition is termed as ankyloglossia or tongue tie. The surgical technique is used to reposition the frenum and correct the functional impairments caused by ankyloglossia. This case report presents a 30 years old male patient with impairment of speech due to the short lingual frenum. 980 nm diode laser was used for frenectomy which showed minimal pain and healing with no complications. Surgical procedures like frenectomy and biopsy of oral lesions can be effectively carried out using Diode laser.

A laser safety analysis for liquid-crystal–on–silicon (LCOS) based imaging projection systems
utilizing laser light sources is presented. It is shown that a typical laser-based imaging projector
is capable of providing a D65 white-balanced luminous flux in excess of 20 lm while remaining Class
1 eye safe. By considering a Class 2 classification, it is shown that the same architecture is capable of
providing several hundred lumens, a performance level which could potentially be applicable to a
new class of high-brightness miniature projection systems.

- by Edward Buckley
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- Optics, Human Factors, Displays, Diode Lasers

Aim: This study aims to evaluate the bacterial reduction after conventional root canal treatment using 5.25% sodium hypochlorite. Materials and Methods: The study criteria included 100 patients requiring root canal treatments due to pulpitis. The diagnosis was made based on objective clinical signs (examination, probing, percussion, palpation) and X-ray investigation. The clinical procedures were carried out under strict aseptic precautions. All patients were subjected to biomechanical preparation followed by irrigation using sodium hypochlorite at a concentration of 5.25% which is considered the highest concentration without causing any toxic effect on the patient. All microbiological samples were taken immediately after the access preparation baseline (S1) and after the completion of the root canal instrumentation and disinfection with 5.25% sodium hypochlorite (S2) and sent for microbiological analysis. Results: One hundred patients with infected root canal were selected for this in vivo study. All S1 samples were positive for microbial isolates, 71 samples harbored cultivable bacterial isolates, 22 were fungus (Candida albican), and 7 samples showed no growth so in total adding up to 151 isolates identified from 100 patients. Bacterial isolates before chemomechanical treatment showed the highest prevalence belonging to Enterococcus faecalis followed by Streptococci, Staphylococci and Candida albican. After the chemomechanical treatment with 5.25% of sodium hypochlorite no cultivable bacteria were isolated from 38 patients root canals, and therefore the treatment managed to eradicate 54% of the 151 isolated bacterial species from the 71 infected root canals. Conclusion: The antimicrobial effect of 5.25% sodium hypochlorite was effective in eradicating a high number of the bacterial isolates along with the fungus identified in infected root canals. This high concentration of sodium hypochlorite presented no toxic damage to the root canal or the area around it when handled with care.

- by zari esa m.saleh
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- Microbiology, Diode Lasers, Sodium Hypochlorite, Endodontics

A 1064 nm wavelength laser was obtained by pumping a Nd:YVO4 crystal using a 808 nm wavelength diode laser. A curved and a flat mirror were used to examine two different cavity mirrors. The Q-switching of this laser was realized using a saturable absorber. Second harmonic generation was performed to obtain both continuous wave and Q-switched 532 nm wavelength laser.

- by Abu Mitul, Ph.D.
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- Solid State Physics, Laser Physics, Laser, Diode Lasers

— The efficiency limiting mechanisms in type-I GaInAsSb-based quantum well (QW) lasers, emitting at 2.3 µm, 2.6 µm and 2.9 µm, are investigated. Temperature characterization techniques and measurements under hydrostatic pressure identify an Auger process as the dominant non-radiative recombination mechanism in these devices. The results are supplemented with hydrostatic pressure measurements from three additional type-I GaInAsSb lasers, extending the wavelength range under investigation from 1.85-2.90 μm. Under hydrostatic pressure, contributions from the CHCC and CHSH Auger mechanisms to the threshold current density can be investigated separately. A simple model is used to fit the non-radiative component of the threshold current density, identifying the dominance of the different Auger losses across the wavelength range of operation. The CHCC mechanism is shown to be the dominant non-radiative process at longer wavelengths (> 2 μm). At shorter wavelengths (< 2 μm) the CHSH mechanism begins to dominate the threshold current, as the bandgap approaches resonance with the spin-orbit split-off band.

- by Shamsul Arafin
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- Semiconductor Devices, Auger Spectroscopy, Diode Lasers

Scanned-beam projection systems have attracted much interest recently, with claimed advantages including power efficiency and potential miniaturization consistent with embedding in mobile devices. However, the laser-safety classification and concomitant performance implications, which are arguably the most important issues pertaining to this technology, remain widely misunderstood. In this paper, Class 1 and 2 laser-safety radiometric image power limits for scanned-beam systems are derived with reference to the IEC 60825-1 standard. By calculating the equivalent photometric measure of luminous flux, it is possible to show that the brightness limits for scannedbeam projection systems using current technology are approximately 1 and 17 lm for Class 1 and 2 safety classifications, respectively.

- by tuzimao huimaqiang
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- Optics, Human Factors, Laser, Safety

- by IJTRA Editor
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- Optics, Optical Fiber Communications, ABC, Diode Lasers

Bachelor's degree thesis.
Universidad Nacional de Ingeniería (UNI)
Managua, Nicaragua

- by Bryan Navarrete
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- Mechatronics & Robotics, Diode Lasers, STM32, CNC Machining

We present a novel implementation of the “phase reconstruction using optical ultra fast differentiation” (PROUD) technique and apply it to characterize the time resolved chirp of a gain switched semiconductor laser. The optical temporal differentiator is a fiber based polarization interferometer. The method provides a fast and simple recovery of the instantaneous frequency from two temporal intensity measurements, obtained by changing the spectral response of the interferometer. Pulses with different shapes and durations of hundreds of picoseconds are fully characterized in amplitude and phase. The technique is validated by comparing the measured pulse spectra with the reconstructed spectra obtained from the intensity and the recovered phase.

- by Antonio Consoli
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- Optical Fiber Communications, Fiber Optics, Interferometry, Diode Lasers

We present the progress made in the development of optical frequency combs generators (OFCG) using Photonic Integrated Circuits (PIC). These are designed and manufactured in a Multi-project Wafer run at generic integration platform. The experimental results of the different OFCG classes are shown, highlighting the bandwidths achieved, in the order of THz. The feasibility of providing miniaturized photonic circuits in broadband systems and other future applications in the framework of nanotechnology is highlighted.

- by F. Vinicio Corral and +1
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- Optical Fiber Communications, Photonic Integrated Circuits, Photonics, Diode Lasers

Mode stability is an important performance characteristic of external cavity diode lasers (ECDLs). It has been well established that the continuous mode-hop-free tuning range of a grating-feedback ECDL can be optimized by rotating the grating about a specific pivot location. We show that similar results can be obtained for other more convenient pivot locations by choosing instead the cavity length and grating location. The relative importance of the temperature stability of the diode and of the external cavity is also evaluated. We show that mechanically simple ECDL designs, using mostly standard components, can readily achieve a 35 GHz mode-hop-free tuning range at 780 nm.

- by Göksel Arhan
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- Mechanical Engineering, Diode Lasers, Grating Feedback, Applied Optics

We propose a secure optical communication system based on the principles of generalized and complete synchronization of chaotic oscillations. Both a transmitter and a receiver are composed by two chaotic external-cavity semiconductor lasers which are coupled in a master-slave configuration to provide generalized synchronization, while the master lasers in the transmitter and in the receiver are completely synchronized via an optical fiber. A message is added to the slave laser in the transmitter and sent to the ...

- by Alexander N Pisarchik
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- Communication, Circuits and Systems, Optical Communication, Synchronization

We report a new simple and inexpensive sub-micrometer two dimensional patterning technique. This technique combines a use of a photomask featured with self-organized particles in the micro-to nanometer size range and a photoresist-covered substrate. The photomask was prepared by depositing monodispersed silicon dioxide (SiO 2 )-or polystyrene-spheres on a quartz substrate to form a close-packed pattern. The patterning technique can be realized in two configurations: a hardcontact mode or a soft-contact mode. In the first configuration, each sphere acts as a micro ball-lens that focuses light and exposes the photoresist underneath the sphere. The developed pattern therefore reproduces exactly the same spatial arrangement as the close-packed spheres but with a feature size of developed hole smaller than the diameter of the sphere. In the softcontact mode, an air gap of few micrometers thick is introduced between the 2D array of self-organized spheres and the photoresist-covered substrate. In this case, a phase mask behavior is obtained which results in an exposure area with a lattice period being half of the sphere diameter. A 2D lattice structure with period and feature size of a developed hole as small as 750 nm and 420 nm, respectively, was realized in this configuration. We further applied this technique to host the deposition of organic films into the 2D nanostructure and demonstrated the realization of green and red nanostructured OLEDs.

- by Alexis Fischer
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- Physics, Optics, Photonic Crystals, Plasmonics

Wavelength-locking by a volume holographic grating (VHG) is reported for a diode laser bar with 49 single mode emitters, fitted with a dual-axis collimation phase-plate for smile elimination and excellent beam pointing correction. The much-improved VHG feedback with the ultracollimated array beam gives 100% wavelength locking at 975 nm over a 17°C temperature range and external cavity lengths up to 110 mm. This enables a folded cavity configuration to provide a fully-locked array with wavelength selection into 200 pm channels over an 8 nm band, suitable for multi-bar dense wavelength-combining.

- by Pelin Demir
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- Optics, Fiber Lasers, Diode Lasers

- by Edward Buckley
- •
- Human Factors, Laser, Displays, Diode Lasers

Ankyloglossia or tongue tie is characterized by short lingual frenum restricting tongue movement which causes feeding difficulties and speech problems. Such condition can be treated by frenectomy using scalpel, laser, and electrocautery. The present case reports ankyloglossia in an 11-year-old female patient treated with diode laser and followed up without any complications.

- by Soni Bista and +1
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- Diode Lasers, Lasers, Laser Tissue İnteractions : Dental Lasers, Ankyloglossia

This paper deals with the simulation and implementation of boost Converter with the need for power factor correction, the utilization of active clamping technique in the boost converter, this circuit incorporation of compound active clamping boost converter, its modes of operation and analysis of step of chopper. This analysis involves the simulation analysis of the compound active clamping boost PFC converter. It gives the details about the circuit implementation. The laboratory model is implemented and the experimental results are obtained. These experimental results are correlated with the simulation results.

Haemangioma is the most common benign tumor of vascular origin of the head and neck region. This paper reports the management of a 39 year old female patient with capillary haemangioma on the ventral surface of the tongue and the floor of... more