optical gain in semiconductor laser
Stimulated Emission and Optical Gain in Semiconductors
... 2004 Marcel Dekker, Inc. 3StimulatedEmissionandOpticalGaininSemiconductorsThischapterpresentsthebasictheoryandcharacteristicsofstimulatedemissionandopticalamplificationgaininsemiconductors.Theformeristhemostimportantprinciplethatenablessemiconductorlaserstobeimplemented,andthelatteristhemostimportantparameterforanalysisofthelaserperformances.First,stimulatedemissioninsemiconductorsisexplained,andthenquantumtheoryanalysisandstatisticanalysisusingthedensitymatrixoftheopticalamplificationgainaregiven.Stimulatedemissionandopticalgaininsemiconductorquantumwellstructureswillbepresentedinthenextchapter.3.1BANDSTRUCTUREOFSEMICONDUCTORSANDSTIMULATEDEMISSION3.1.1BandStructureofDirect-TransitionBandgapSemiconductorsSemiconductorlasersutilizetheinterbandopticaltransitionsofcarriersinasemiconductorhavingadirect-transitionbandgap.Asiswellknownintheelectrontheoryofsolids[1],thewavefunctionofanelectronofwavevectork(momentumhhk)inanidealsemiconductorcrystalcanbewrittenasaBlochfunctionj ... 3StimulatedEmissionandOpticalGaininSemiconductorsThischapterpresentsthebasictheoryandcharacteristicsofstimulatedemissionandopticalamplificationgaininsemiconductors.Theformeristhemostimportantprinciplethatenablessemiconductorlaserstobeimplemented,andthelatteristhemostimportantparameterforanalysisofthelaserperformances.First,stimulatedemissioninsemiconductorsisexplained,andthenquantumtheoryanalysisandstatisticanalysisusingthedensitymatrixoftheopticalamplificationgainaregiven.Stimulatedemissionandopticalgaininsemiconductorquantumwellstructureswillbepresentedinthenextchapter.3.1BANDSTRUCTUREOFSEMICONDUCTORSANDSTIMULATEDEMISSION3.1.1BandStructureofDirect-TransitionBandgapSemiconductorsSemiconductorlasersutilizetheinterbandopticaltransitionsofcarriersinasemiconductorhavingadirect-transitionbandgap.Asiswellknownintheelectrontheoryofsolids[1],thewavefunctionofanelectronofwavevectork(momentumhhk)inanidealsemiconductorcrystalcanbewrittenasaBlochfunctionj ... in inversion occupation probability difference f2À f1and gain spectrum g(hh!) with increasing carrier injection.Stimulated Emission and Optical Gain 45Copyright â 2004 Marcel Dekker, Inc....
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Sửa chữa máy in hp laserjet 5l và 6l
... tục in. CHƯƠNG 1: THÔNG TIN VỀ SẢN PHẨM1.1. ĐẶC TÍNH KỸ THUẬT CỦA MÁY IN Bảng 1.1. Đặc tính kỹ thuật của máy in Đặc tính kỹ thuật Miêu tảTốc độ in 4 trang trên phút (đối vói máy in HP LaserJet ... đó in lại (xem chương 3, “các thiết lập máy in PCL”.6. Nếu thay đổi chế độ Auto Continue (tự động tiếp tục) có bật PJL, máy in sẽ tiếp tục in sau 10 giây.7. Nếu thay đổi chế độ Auto Continue ... vào máy in. Lắp lại nắp che khe cắm bộ nhớ mở rộng, dựng máy in thẳng lên, và cấp nguồn cho máy in. In một bản in kiểm tra (xem chương 3) để kiểm tra xem bộ nhớ đã được thêm vào máy in của...
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Báo cáo " Wavelength shift in microsphere lasers " pptx
... choosing the coupling point in the half taper i.e. adjusting the distancefrom tip to acceptance point we may also find the appropriate position to select one lasing mode.a) b)Fig. 3. Selecting ... Estimating the micro-sphere diameter through peaks distance in these spectrums gave result well matched the one receivedby optical method. When increasing the pump intensity we obtained laser ... b)Fig. 3. Selecting a single laser mode by changing the acceptance angle: a) three lines emission, marker at1534.4 nm b) single line at 1534.4 nm.Fig. 4. The wavelength shift in laser spectrum, microsphere...
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Báo cáo " The dependence of the parametric transformation coefficient of acoustic and optical phonons in doped superlattices on concentration of impurities" pot
... low-dimensional semiconductor. 5. Conclusions In this paper, we obtain analytic expression of the parametric transformation coefficient of acoustic and optical phonons in doped superlattices in presence ... combination frequency qlυ±Ωr (l=1,2,3,4…) will appear. If among the CDW there exits a certain wave having a frequency which coincides, or approximately coincides, with the frequency of optical ... received in revised form 15 August 2009 Abstract. The parametric transformation of acoustic and optical phonons in doped superlattices is theoretically studied by using a set of quantum kinetic...
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![Báo cáo khoa học: Benzo[a]pyrene impairs b-adrenergic stimulation of adipose tissue lipolysis and causes weight gain in mice A novel molecular mechanism of toxicity for a common food pollutant doc](https://media.store123doc.com/images/document/14/rc/rp/small_luUKRIz7Xm.jpg)
Báo cáo khoa học: Benzo[a]pyrene impairs b-adrenergic stimulation of adipose tissue lipolysis and causes weight gain in mice A novel molecular mechanism of toxicity for a common food pollutant doc
... low doses of norepinephrineexerted a significant inhibition on lipoysis (Fig. 1C).The initial step involved in the epinephrine ⁄ nor-epinephrine-induced lipolytic cascade includes activa-tion ... lgặkg)1epinephrine (d) or saline (s), or (B)0.5 mgặkg)1B[a]P for the indicated times prior to receiving injections of either saline or 0.25 mgặkg)1epinephrine. Forty-ve minutes afterinjection ... differences in FFA concentrations between epinephrine and saline incubations (A). (B)Effect of 15 min preincubation of human adipocytes with either B[a]P (j) or saline (h) followed by 45 min incubation...
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heat transfer in femtosecond laserprocessing of metal
... theFEMTOSECOND LASER PROCESSING OF METAL 223 Downloaded By: [Ingenta Content Distribution] At: 19:07 13 December 2007 Similar delays in the beginning of melting were observed during experiments onaluminum ... Thermal Lagging in Ultrafast Laser Heating, Int. J. Heat Mass Transfer, vol. 44, pp. 1725–1734, 2001.10. L S. Kuo and T. Q. Qiu, Microscale Energy Transfer during Picosecond Laser Melting ofMetal ... superheating andthat a distinct melt phase develops with duration of the order of nanoseconds.INTRODUCTION In the last few years, the use of femtosecond lasers in materials processing andrelated...
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molecular dynamics simulation of thermal and thermomechanical phenomena in picosecond laser material interaction
... phenomena in picosecond laser material interactionXinwei Wanga,*, Xianfan XubaDepartment of Mechanical Engineering, N104 Walter Scott Engineering Center, The University of Nebraska at Lincoln,Lincoln, ... pulsed laser materials interaction has attracted considerable attention owing to the rapiddevelopment of short pulsed lasers and their potential applications in laser- material processing. In this ... revealing the mecha-nism behind the thermal and thermomechanical phe-nomena in ultrafast laser materials interaction. In the past several years, many MD simulations of laser materials interaction...
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explosive phase transformation in excimer laser ablation
... fluence in the medium fluence region, i.e., extinction of the laser beam in the plume does not vary with the laser intensity in the medium fluence region. Extinction ofthe laser beam is determined ... the boiling pointwx5 . The superheating process is represented by the‘superheating’ line in Fig. 1. However, there is awell defined upper limit for superheating of a liquid,Ž.the spinode ... heating process of a liquid metalby a pulsed laser beam, the phase diagram in theneighborhood of the critical temperature is shown in wxFig. 1 4 . The ‘normal heating’ line indicates theheating...
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heat transfer in femtosecond laser
... Thermal Lagging in Ultrafast Laser Heating, Int. J. Heat Mass Transfer, vol. 44, pp. 1725–1734, 2001.10. L S. Kuo and T. Q. Qiu, Microscale Energy Transfer during Picosecond Laser Melting ofMetal ... numerically to predict heating, melting, and evaporation of metal under femtosecond laser irradiation. Kinetic relations at the phase-change interfaces are included in the model.The numerical ... found in the literature [1]. This interest has beensparked by the fact that ultrashort lasers offer considerable advantages in machiningapplications, chief among which are the abilities to machine...
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phase explosion and its time lag in nanosecond laser ablation
... lag in nanosecond laser ablationXianfan Xu*School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-1288, USAAbstractThis work investigates interface kinetics during ... beamthrough the laser- induced vapor plume, scattering of laser beam from the laser- induced vapor plume, tran-sient location and velocity of the laser- induced vaporfront, and ablation depth per laser ... includingpulsed laser deposition and micromachining. Phaseexplosion induced by laser heating will be brieflydescribed. The nucleation process and its time lag in a superheated liquid leading to phase...
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fowler-nordheim field emission effects in semiconductor nanostructures
... IV–VIsemiconductors has been studied taking PbTe as an example.The stressed semiconductors are being investigated for strained silicon transis-tors, quantum cascade lasers, semiconductor strain ... been investigated [158–165]. These studies revealed some ofthe interesting features that had been seen in bulk PbTe, such as Fermi level pinning in the case of superconductivity [166]. In Sect. ... Tellurium (Te) has been used as the semiconductor layer in thin-film transistors (TFT) [171], which is being used in CO2 laser detectors [172],electronic imaging, strain-sensitive devices [173,174],...
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Báo cáo hóa học: " Size-dependent Fano Interaction in the Laser-etched Silicon Nanostructures" docx
... red shift, and FWHM in Raman line-shape increase by the increasing excitation laser power density. Changes in the Raman line-shape arereversible in nature on decreasing the laser power density.This ... heating. Increase in the asymmetry on increasing excitation laser power densityis due to Fano interaction between electronic Ramanscattering involving photo-excited electrons within elec-tronic ... of phonons in the Si NSs.Many others [3, 4] have explained the asymmetry anddownshift in the Raman line-shape in terms of a com-bined effect of quantum confinement and laser heating.Magidson...
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