History and Developments of Semiconductor Lasers

A brief history of the creation of semiconductor lasers is presented. Basic attention is given to injection lasers including homo- and heterojunction laser diodes, quantum-well heterostructures, quantum cascade systems, etc. General steps in the development of the semiconductor lasers and inventions in the injection lasers are described. Theory modeling the spectral and output characteristics of the laser semiconductor sources is discussed. Set of applied semiconductor materials for laser technology and techniques and number of corresponding lasing wavelengths are listed. In addition, principal fields of application of semiconductor lasers and as well as growing total volume in the laser market are involved. Modern trends in semiconductor quantum electronics are also grounded

Abnormal Character of the Diffusivity-mobility Ratio in Doping Superlattices

The influence of high level of doping in type n-i-p-i crystal structures on electron and hole state distributions is examined. Abnormal behaviour in the diffusivity- mobility ratio due to shortening of the density state tails under excitation of doping Superlattices is described

Production of broadband modal gain spectra in asymmetric multiple quantum-well Ga0.47In0.53As/Ga0.18In0.82As0.4P0.6 heterostructures

The modal gain spectra of asymmetric multiple quantum-well Ga0.47In0.53As/Ga0.18In0.82As0.4P0.6 hetero- structures are theoretically analysed within the framework of the four-band kp method. An efficient procedure for obtaining the broadband and almost êat gain spectrum is proposed. The designs of semiconductor radiation sources with different sets of nonuniformly excited quantum wells producing broadband amplification in spectral ranges from 1.28 to 1.525 \mu m and from 1.36 to 1.6 \mu m are calculated

Calculation of energy characteristics for Si1-xGex-Si strucrures with single quantum wells

Energy characteristics of Si1–xGex–Si quantum-size structures with single quantum wells were calculated numerically based on a four-band k⋅p method. Analytical expressions for the Luttinger parameters are obtained as functions of the component composition of Si1–xGex compounds. Analytical expressions for the energy h−ω of optical band-to-band transitions are obtained in an effective mass approximation and agree well with numerical calculations by the k⋅p method. This allows one to determine accurately a range of changes while varying the component compositions and thickness of the active and barrier layers

Carrier transport and screening in n-i-p-i crystals

The variation of the energy spectrum of n-i-p-i crystals under excitation was examined and the influence of the reduction of the screening length on the ratio between the coefficient of diffusion and the mobility of the current carriers was established. It is shown that the filling of subband states by carriers results in an anomalous behaviour of the diffusivity-mobility ratio. The effect occurs in the electric quantum limit and at room temperature as well

Nonlinear gain and bistability in photonic crystal heterostructures with compositional and doping superlattices

Optical properties of photonic crystal heterostructures with embedded n–i–p–i superlattices are studied. Nonlinear behavior of the transmission and reflection spectra near the defect mode is investigated. Self-consistent calculations of the output performance characteristics are performed using the transfer-matrix method and taking into account the gain saturation. Features and characteristic parameters of the nonlinear gain in active n–i–p–i layers are determined. Detail analysis of the gain saturation and accompanying nonlinear refraction effects is carried out for one-dimensional photonic crystal heterostructure amplifiers in the GaAs–GaInP system having at the central part an active “defect” from the doubled GaAs n-i-p-i crystal. The gain saturation in the active layers in the vicinity of the defect changes the index contrast of the photonic structure and makes worse the emission at the defect mode. Spectral bistability effect which can be exhibited in photonic crystal heterostructure amplifiers is predicted and the hysteresis loop and other attending phenomena are described. The bistability behavior and modulation response efficiency demonstrate the potential possibilities of the photonic crystal heterostructures with n-i-p-i layers as high-speed optical amplifiers and switches

Терапевтичні можливості карбокситерапії при псоріазі

Topicality. Psoriasis is a chronic autoimmune disease characterized by changes in the growth and differentiation of the epidermis. 2-5 % of the population of the planet have psoriasis, and it is 30 % in the structure of skin diseases. The multifactorial concept of the pathological process in psoriasis determines a wide range of pharmacotherapy of this disease. Modern antipsoriatic agents are not effective enough and have a variety of side effects.Aim. To summarize the existing scientific literature data conserning the possibility of treating psoriasis with carboxytherapy.Results and discussion. Carboxytherapy is an important part of the treatment and rehabilitation of patients with psoriasis. The antipsoriatic effect of carboxytherapy is realized through the local and resorptive effect of CO2: antiproliferative, antiinflammatory, antioxidant, antimicrobial, antihypertrophic, reparative and analgesic. Carboxytherapy in psoriasis promotes tissue detoxification, improves immunity, improves tissue trophism, and eliminates venous-interstitial lymphatic stagnation due to hemodynamic, tissue, and biochemical mechanisms of action of CO2.Conclusions. Carboxytherapy as an additional alternative to pharmacotherapy has a synergistic effect together with formulary therapy, but at the same time reduces the dosage of approved drugs and their side effects.Актуальность. Псориаз – хроническое аутоиммунное заболевание, которое характеризуется изменениями роста и дифференцировки эпидермиса. Псориазом болеют 2-5 % населения планеты, а в структуре заболеваний кожи он составляет 30 %. Мультифакторная концепция патологического процесса при псориазе определяет широкий спектр фармакотерапии этого заболевания. Современные антипсориатические средства недостаточно эффективны и оказывают разнообразные побочные эффекты.Цель работы. Обобщить имеющиеся в научной литературе данные о возможности лечения псориаза при помощи карбокситерапии.Результаты и их обсуждение. Карбокситерапия является важной составной частью лечения и реабилитации больных псориазом. Антипсориатический  эффект карбокситерапии реализуется посредством локального и резорбтивного действия СО2:  антипролиферативного, противовоспалительного, антиоксидантного, антимикробного, антигипоксического, репаративного и болеутоляющего. Карбокситерапия при псориазе способствует тканевой детоксикации, повышает иммунитет, улучшает трофику тканей, ликвидирует венозно-интерстициальный лимфатический застой за счет гемодинамических, тканевых и биохимических механизмов действия СО2.Выводы. Карбокситерапия как дополнительная альтернатива фармакотерапии оказывает синергическое действие совместно с формулярной терапией, но одновременно уменьшает дозирование утвержденных лекарств и их побочное действие.Актуальність. Псоріаз – хронічне аутоімунне захворювання, яке характеризується змінами росту і диференціювання епідермісу. На псоріаз хворіють 2-5 % населення планети, а в структурі захворювань шкіри він становить 30 %. Мультифакторна концепція патологічного процесу при псоріазі визначає широкий спектр фармакотерапії цього захворювання. Сучасні антипсоріатичні препарати недостатньо ефективні і чинять різноманітні побічні ефекти.Мета роботи. Узагальнити наявні в науковій літературі дані про можливості лікування псоріазу за допомогою карбокситерапії.Результати та їх обговорення. Карбокситерапія є важливою складовою частиною лікування і реабілітації хворих на псоріаз. Антипсоріатичний ефект карбокситерапії реалізується за допомогою локальної і резорбтивної дії СО2: антипроліферативної, протизапальної, антиоксидантної, антимікробної, антигіпоксичної, репаративної і болезаспокійливої. Карбокситерапія при псоріазі сприяє тканинній детоксикації, підвищує імунітет, поліпшує трофіку тканин, ліквідує венозно-інтерстиціальний лімфатичний застій за рахунок гемодинамічних, тканинних і біохімічних механізмів дії СО2.Висновки. Карбокситерапія як додаткова альтернатива фармакотерапії надає синергічну дію спільно з формулярною терапією, але одночасно зменшує дозування затверджених ліків і їх побічні ефекти

Nonlinearities in the reflection and transmission spectra of the photonic bandgap heterostructures with n–i–p–i crystals

Nonlinear optical properties of photonic crystal heterostructures with embedded n–i–p–i superlattices are investigated. Self-consistent calculations of the transmission and reflection spectra near the defect mode are performed using the transfer-matrix method and taking into account the gain saturation. Analysis of features and output characteristics is carried out for one-dimensional photonic crystal heterostructure amplifiers in the GaAs–GaInP system having at the central part an active “defect” from doubled GaAs n–i–p–i crystal layers. The gain saturation in the active layers in the vicinity of the defect changes the index contrast of the photonic structure and makes worse the emission at the defect mode. Spectral bistability effect, which can be exhibited in photonic crystal heterostructure amplifiers, is predicted and the hysteresis loop and other attending phenomena are described. The bistability behavior and modulation response efficiency demonstrate the potential possibilities of the photonic crystal heterostructures with n–i–p–i layers as high-speed optical amplifiers and switches