Use Of Semiconductor Lasers Research Articles

AuSn Preform Thickness’s Effect on Thermal Management in Semiconductor Laser Applications

For the plethora of applications that require a high-melting die-attach solder, 80Au/20Sn is a great choice to ensure good performance and reliability, especially when used in one of its most highly demanded applications: semiconductor laser die-attach. However, difficulty managing thermal heat transfer has prevented the widespread use of semiconductor lasers. When the operational heat of these devices increases, their longevity and potential become limited. One option to improve thermal transfer is to use a thinner 80Au/20Sn preform in the bondline, which allows the heat to transfer to the heat-sink more quickly and efficiently. The creation of voiding hot spots—due to the lack of solder volume—is a perceived concern when using a thinner preform in the solder joint, which then contradicts the original intention. Voiding percentages were defined for several 80Au/20Sn preform thicknesses—ranging from 0.002″ to 0.00035″ thick—allowing for conclusions to be drawn on the effect of 80Au/20Sn preform thickness on thermal transfer in semiconductor laser technologies.

A new approach in the treatment of chronic bilateral paralytic stenosis of the larynx: A review

The issues of surgical treatment of bilateral paralytic stenosis of the larynx do not lose their relevance today, since the proportion of patients suffering from this pathology is steadily increasing. Neurogenic disorders of laryngeal motor function most often occur due to previous surgical intervention on the thyroid gland and upper mediastinum. The predominant complaints of such patients are dyspnea, decreased tolerance to physical exertion and impaired lantern function. Thus, the main objectives in the treatment of chronic laryngeal stenosis are: restoration of the lumen of the vocal slit to ensure adequate respiratory function, prevention of respiratory failure and preservation of socially significant voice. The use of semiconductor lasers for laryngoplasty in bilateral paralytic stenoses of the larynx is a very common technique, however, there are no data in the literature on the use of semiconductor laser energy with a wave length of 445 nm for this surgical intervention. In their work the authors tried to show the advantages of the surgical treatment of bilateral paralytic laryngeal stenosis using 445 nm semiconductor laser, developed at the Saint Petersburg Research Institute of Ear, Throat, Nose and Speech, which allowed to reduce rehabilitation period of respiratory function and preserve socially significant voice, using a clinical example.

Combined Effects of Topical Fluorides and Semiconductor Lasers on Prevention of Enamel Caries: A Systematic Review and Meta-Analysis.

Objective: To compare the effects of combined treatment of topical fluoride and semiconductor laser (F&L) with topically using fluoride (F) on remineralization and prevention of enamel caries. Background: There is no agreement on whether semiconductor lasers can promote the effect of topical fluoride on the remineralization and prevention of dental caries. This study is the first systematic review and meta-analysis to investigate the pooled effect of data from studies that compared the combined use of semiconductor lasers and topical fluorides with the single use of fluoride on remineralization and prevention of caries. Methods: We performed literature search on Scopus, Web of Science, and PubMed. The keywords were as follows: ((diode lasers) OR (diode laser) OR (quantum cascade laser) OR (quantum cascade lasers) OR (Gallium Aluminum Arsenide lasers) OR (Gallium Aluminum Arsenide laser) OR (GaAlAs lasers) OR (GaAlAs Laser) OR (semiconductor laser) OR (semiconductor lasers)) AND ((caries) OR (dental caries) OR (remineralisation) OR (remineralization) OR (demineralization) OR (demineralisation)) AND fluoride. We carried out meta-analysis to compare the microhardness of demineralized enamel, lesion depth (LD), and percent reduction of calcium (Ca%) of sound enamel receiving F&L with F. Results: The search identified nine laboratory studies, which used 445 to 980 nm semiconductor lasers with various fluorides. The standard mean difference of microhardness of demineralized enamel between F&L and F was 1.06 [95% confidence interval (CI): 0.12 to 2.00, p = 0.03]. No difference was found in LD (95% CI: -1.63 to 0.10, p = 0.08) and Ca% (95% CI: -0.52 to 1.28, p = 0.40) on sound enamel between the two groups. Conclusions: Semiconductor lasers enhance the effect of fluoride on remineralizing but not on preventing enamel caries. Moreover, substantial heterogeneity was found among the studies, and the results should be interpreted cautiously.

Optimization of power supply mode of single-mode laser diode by ratio of current and integral spectrum parameter

Bursting development of the technological base of semiconductor quantum electronics determined the width of the domain for use of semiconductor lasers in optical-electronic measuring systems based on the optical methods of stream research. In order to improve the accuracy of such systems, it is proposed to use a simple technique for optimizing the supply mode of a single-mode laser diode, based on an analysis of the current dependence of its integral spectral parameter. It is shown that the optimal value of the pumping current appears when the radiation spectrum envelope line tends to match the normalized Gaussian curve within the width of the spectral line.

The Impact of AuSn Preforms Thickness on Solder Joint Reliability

Abstract A hurdle that prevents widespread use of semiconductor lasers is that their performance is negatively impacted by thermal management. New products like stack layer diodes have a large number of lasers that work all at once in the condense area. When semiconductor laser dies' operational heat increases, the power of the laser decreases. A technique that is helping users overcome this hurdle is the application of a thinner 80Au20Sn solder joint for the die-attach to aid in thermal transfer to copper heat sinks. The paper looks at a variety of different preform thicknesses, ranging from 0.0002″ to 0.0015″, and it also reviews voiding percentages. Our study tested shear strength and looked at how preform thickness impacts joint integrity. Further, we took a more in-depth look at the intermetallic thickness on ultra-thin preforms and observed how it affected the solder joint strength. Finally, we looked at other factors like surface tension and at what thickness preform this starts to impact voiding and performance. The paper will help engineers gain insight into what preform thickness will be the optimal choice for laser diode applications as well as other die-attach applications.

Application of semiconductor LED laser generators in otorhinolaryngology

The review article provides brief data on the classification of lasers in medicine, the history of the use of therapeutic lasers. The problems of the use of semiconductor lasers in inflammatory diseases of various etiologies, as well as in various diseases of ENT organs, in particular, in diseases of the middle ear are considered.

Fast random number generation with spontaneous emission noise of a single-mode semiconductor laser

We experimentally demonstrate a 12.5 Gb s−1 random number generator based on measuring the spontaneous emission noise of a single-mode semiconductor laser. The spontaneous emission of light is quantum mechanical in nature and is an inborn physical entropy source of true randomness. By combining a high-speed analog-to-digital converter and off-line processing, random numbers are extracted from the spontaneous emission with the verified randomness. The generator is simple, robust, and with no need of accurately tuning the comparison threshold. The use of semiconductor lasers makes it particularly compatible with the delivery of random numbers in optical networks.

The study of temperature effect on the performance characteristics of the InGaN-based vertical cavity surface emitting laser (VCSEL) by solving the rate equations

The use of semiconductor lasers is beneficial in long-distance communications. Practical communication systems based on these lasers need high ambient temperature, with temperature changes between [Formula: see text]C and [Formula: see text]C. The study of the temperature-dependent response of these lasers is important to improve them. This study investigates the effect of temperature on InGaN-based vertical cavity surface emitting lasers (VCSEL). The active region in this structure includes a single quantum well (SQW). The rate equations of carriers and densities are numerically solved. The time variations of carrier density, photon density and output power ([Formula: see text], [Formula: see text] and [Formula: see text]) at [Formula: see text]C and the current injection of 0.04 A are obtained. Values obtained for threshold current and output power include 7 mA and 44 mW, respectively. The effect of temperature on the time variations of [Formula: see text], [Formula: see text] and [Formula: see text] from [Formula: see text]C to [Formula: see text]C is studied. Results show that these parameters decrease and the threshold current increases with an increase in temperature. Furthermore, the investigation of the effect of injection current on [Formula: see text], [Formula: see text] and [Formula: see text] shows that raising the injection current can increase these parameters. Moreover, an increase in the injection current reduces the time response.

Effective Linewidth of Semiconductor Lasers for Coherent Optical Data Links

We discuss the implications of using monolithically integrated semiconductor lasers in high capacity optical coherent links suitable for metro applications, where the integration capabilities of semiconductor lasers make them an attractive candidate to reduce transceiver cost. By investigating semiconductor laser frequency noise profiles we show that carrier induced frequency noise plays an important role in system performance. We point out that, when such lasers are employed, the commonly used laser linewidth fails to estimate system performance, and we propose an alternative figure of merit that we name “Effective Linewidth”. We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28 Gbaud DP-16QAM over an optical link. Our investigations cover the use of semiconductor lasers both in the transmitter side and as a local oscillator at the receiver. The obtained results show that our proposed “effective linewidth” is easy to measure and accounts for frequency noise more accurately, and hence the penalties associated to phase noise in the received signal.

DEVELOPMENT OF TRANSMYOCARDIAL LASER REVASCULARIZATION IN PATIENTS WITH ISCHEMIC HEART DISEASE

The use of laser radiation in cardiac surgery allows to provide more effective and targeted care for patients with ischemic heart disease. The article summarizes the multistage teamwork of several research centers in Tomsk on determination of the most effective type of laser and techniques of cardiac surgery using lasers. The study had an experimental and a clinical phase. In the experimental phase, effectiveness of various laser types for indirect laser myocardial revascularization was assessed, including carbon dioxide, neodymium, and a semiconductor laser types. During clinical phase, efficacy of clinical use of semiconductor laser in various timepoints after surgery was evaluated. The experimental phase revealed that semiconductor laser provides the best neoangiogenesis efficiency, minimal myocardial damage and ease of use. During clinical phase, its safety for a patient was established and a significant clinical benefit was observed.

Semiconductor Laser Multi-Spectral Sensing and Imaging

Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

Researches of peak analog modulation of semi-conductor lasers in view of effects of ageing

Are investigated amplitude - frequency characteristics of injection semi-conductor lasers. Measurements of factors of nonlinear distortions and depths of peak modulation of such lasers in a current mode the microwave modulation are executed. Experimental researches are carried out with use of semi-conductor lasers after their long warehousing modeling effects of ageing.

Aeronautical use of semiconductor lasers for short optical pulses

In this paper, we investigate the feasible schemes to generate periodic optical pulses of width between several picoseconds (ps) and tens ps. Gain-switched semiconductor laser diodes are shown to be more suitable for avionics applications than mode-locked laser diodes. In the experiment, we use a low-cost Fabry-Perot laser diode to generate short optical pulse streams. A simple optical injection-locking scheme is then used to reduce the timing jitter and frequency chirp in such laser diodes, which in turn can improve the transmission performance of the generated optical pulses. It is expected that the use of gain-switched semiconductor lasers can meet the requirement of high-speed airborne communication networks or ground supporting systems at airports. Moreover, we discuss the possibility of using the pulsed semiconductor lasers to generate millimetre-wave (mm-wave) signals for future applications to airborne high-resolution, mm-wave radars.

Fiber Optic Probe Applications Using Near-Infrared Compounds: Determination of NaOH

Abstract The development of a near-infrared fiber optic probe (FOPP) for the determination of caustic soda will be reported. The utility of the FOPP is demonstrated using an NIR non-commercially available tetrasubstituted chloroaluminum naphthalocyanine NIR dye which is susceptible to pH changes in solutions. The naphthalocyanine derivatives have been synthesized in our laboratories. The spectral characteristics of these NIR dyes, are above 700 nm and the absorbance maximum is a perfect match for the use of semiconductor laser diodes as the excitation source. The response of the Q-band against solution pHs and caustic soda will be reported. The FOPP consists of a semiconductor laser diode (λmax=780 nm), an NIR dye and a detector. The probe made of poly(methyl methacrylate) serves as a support for a permeable polymer that is used for the entrapment of the NIR dye (about < 2mm in diameter). The permeable polymers used were Nafion and Gelatin. As hydrogen ions diffuse through the permeable polymer, a complex is formed with the dye, accompanied by changes in the spectral characteristics of the dye. Excitation of the complex is induced with a semiconductor laser diode at 780 nm. The probe shows good reproducibility of the data in NaOH measurements. Also the molar absorption coefficient of these dyes at different concentrations of polymer will be reported. The effect of Nafion on the spectral characteristics of the NIR dyes will be presented. The general procedure used for the attachment of the dye to the distal end of the probe can be used to construct compact non-invasive detectors. The use of photodiodes as detertors will be discussed. Use of smaller components shown here will allow for the manufacturing of portable instruments for applications in medicine and industry.

A Basic Study on the Use of Semiconductor Laser of Penetrative Sensitivity on Living Tissue

The penetrative sensitivity of Ga-Al-As semi-conductor laser (790nm, 60mW, continuous wave) in living tissue were evaluated the amount and the distribution of the laser beam on the penetrative side were quantified. Tissues used in this study consist of mandi bular cortical bone derived from human or ox, masseter muscle and fat tissue from ox, white meat of chicken and human venous blood which were all collected on the same day of mesurement. Five samples of each tissue were investigated in fresh status the transmittance and the attenuance of each sample were calculated, and finally following results were indicated.1. Contact irradiation was more effective for the reduction of energy loss on tissue surface than incontact method.2. Percent transmittance of either human or ox mandibular cortical bone in 1.0mm thickness reached approximately 50%. The distribution of the beam power on the penetrative side showed remarkable scattering and some absorption through the same sample.3. The transmittance of masseter muscle and fat tissue from ox close to cortical bone but chicken white meat showed high transmittance of 75% in 1.0mm thickness. In the analysis of the distribution of energy on penetrative side of these three soft tissues, resemble patterns produced under the mixed effects of absorption and scattering were observed.4. Human venous blood indicated low level of the transmittance as compared with other tissues. According to the results of analysis on power distribution, the laser beam seemed to be attenuated by absorption rather than by scattering.5. Attenuation of the laser beam in accordance with the thickness was similar to the graph which was led to Kubelka-Munk's formula for the attenuation of scattering light.

InP substrate temperature measurements in a horizontal, low-pressure metalorganic chemical vapor deposition reactor by infrared laser interferometric thermometry

Infrared laser interferometric thermometry was used to measure InP substrate temperatures in a horizontal, low pressure metalorganic chemical vapor deposition (MOCVD) reactor. These measurements were made by using a 1.53 μm distributed feedback laser, demonstrating the use of semiconductor lasers to diagnose an epitaxial crystal growth process. The laser beam was reflected off of 2 inch diameter (100) n-type InP substrates in a commercial low-pressure MOCVD reactor. Substrate temperature profiles were taken as a function of reactor pressure from 20–1000 mbar and as a function of substrate position on the susceptor. For a constant susceptor set-point temperature of 640°C, temperatures increase monotonically from 600 to 615°C at 20 mbar along the substrate in the gas flow direction, increasing to 621 to 655°C at 1000 mbar for a substrate positioned in the downstream location of a two-well susceptor used for normal epitaxial growth runs. The variation in temperature decreases when the substrate is placed in a center well susceptor. The data shows that improvements in temperature uniformity, and hence compositional uniformity can be achieved by judicious choice of substrate position and reactor pressure. In particular, uniform temperature profiles resulted in improved compositional uniformity obtained for 1.15 μm InGaAsP layers grown on a 2 inch diameter substrate placed in the center well susceptor.

Spectroscopic studies of a near-infrared absorbing pH sensitive carbocyanine dye

Near-infrared dyes can be derivatized with appropriate functional groups for use as analytical probes for numerous applications. A dye derivatized with pH-sensitive functional groups may show spectral changes when the pH of its environment is changed. These dyes are valuable to the researcher since they absorb and fluoresce at long wavelengths where interference is minimal and their absorption maxima permit the use of semiconductor lasers. In this paper we have evaluated the sensitivity to pH of a bis-carboxylic acid derivative of a near infrared dye to illustrate its potential as a probe for determining pH. The dye has an absorption maximum at 795 nm in aqueous solution, a region where several commercially available laser diodes have their output maximum. The analytical utility of near-infrared laser diodes for pH determination has also been evaluated.

Spatial Resolution and Data Addressing of Frequency Domain Optical Storage Materials in the Near IR Regime

This paper reports recent advances in the study of Frequency domain optical storage (FDOS) based on the photochemical hole-burning (PHB) method. New PHB systems are introduced which operate in the near IR regime and are suitable for the use of semiconductor lasers. Furthermore experiments to determine the spatial resolution of the method are presented. Future applications will also be discussed.

Present status of medical use of semiconductor lasers.

Present status of medical use of semiconductor lasers.

アモルファスＧｄＣｏ薄膜の磁気光学スペクトル

Spectral dependences of polar magneto-optical effect-Kerr rotation and reflectance magneto-circular dichroism (RMCD) -of rf-sputtered Gd-Co films have been studied. The Kerr rotation angle increases slightly toward longer wavelength with a hump around 11.2 μm. This result favors the use of semiconductor lasers for optical reading-out of recorded signals on the Gd-Co disk. In the RMCD spectra a sign reversal is observed at certain wavelength between 0.6 and 1.1 μm, which depends strongly on the bias voltage applied during film preparation. Influence on the RMCD spectrum of oxygen introduced during bias-sputtering has also been studied.