共查询到20条相似文献,搜索用时 46 毫秒
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Mortazy E. Ahmadi V. Moravvej-Farshi M.K. 《Quantum Electronics, IEEE Journal of》2002,38(10):1366-1371
Relative intensity noise (RIN) and the frequency/phase noise spectrum (FNS) equivalent circuit of a multimode semiconductor laser diode are derived from multimode rate equations with the inclusion of noise Langevin sources. FNS is an important parameter in optical communication systems, and its circuit model is presented, for the first time, in this paper. Both circuit models for RIN and FNS are integrated in one circuit. RIN and FNS are calculated as functions of frequency, output power, and mode number. It is shown that the RIN of the main mode is increased in the multimode lasers with higher mode numbers. Furthermore, we show that RIN and FNS are enhanced for higher output power. The dependency of a multimode laser diode linewidth on output power is also analyzed using the model. 相似文献
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Transverse-mode dynamics in directly modulated vertical-cavity surface-emitting lasers with optical feedback 总被引:1,自引:0,他引:1
Torre M.S. Masoller C. Mandel P. Shore K.A. 《Quantum Electronics, IEEE Journal of》2004,40(6):620-628
Vertical-cavity surface-emitting lasers (VCSELs) with optical feedback are known to exhibit different transverse-mode regimes depending on the injection current. Close to threshold a VCSEL operates on the fundamental transverse mode, while for larger injection the dynamics is often multimode, with the optical feedback inducing either in-phase or anti-phase transverse mode oscillations. In this paper, we study numerically the influence of current modulation on these different feedback-induced transverse-mode regimes. The modulation amplitude and period are taken as control parameters. We find that the in-phase and anti-phase regimes are robust under weak modulation. As the modulation amplitude increases, there is a transition to a dynamics governed by the current modulation, where the total output power follows the injection current and there is either single-mode or in-phase multimode behavior. However, the effect of the current modulation depends on the modulation period. Under fast modulation, the laser cannot follow the modulation and the optical-feedback-induced effects are dominant. On the contrary, under slow modulation there is a superposition of modulation and feedback effects, with the total output following the modulated current and an underlying transverse-mode behavior mainly determined by the optical feedback. A resonant behavior was observed for modulation periods close to the internal oscillation period. In this case, current modulation induces pulsing output intensity with single-mode or in-phase multimode behavior. 相似文献
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近年来,激光雷达应用对探测距离和灵敏度提出了更高的要求。905 nm半导体激光器作为其理想光源也亟待提升峰值功率与光束质量。在这个背景下,基于非对称大光腔结构研究了不同增益区类型和波导结构对905 nm隧道结脉冲半导体激光器的光束质量和功率效率的影响。通过优化增益区类型和波导结构降低了体电阻和内损耗;增强了限制载流子泄露的能力,提高了器件在高电流下工作的峰值功率和电光效率;通过提高高阶模对基模的阈值增益比值,抑制高阶模式激射,降低了远场发散角。在此基础上,研制的800 μm腔长、200 μm条宽的四有源区半导体激光器在100 ns脉冲宽度、1 kHz重复频率的脉冲功率测试中,41.6 A的脉冲电流强度下实现了峰值功率输出177 W;垂直于PN结方向单模激射,远场发散角半高全宽为24.3°。 相似文献
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High-power and tunable operation of erbium-ytterbium Co-doped cladding-pumped fiber lasers 总被引:7,自引:0,他引:7
Nilsson J. Alam S.-U. Alvarez-Chavez J.A. Turner P.W. Clarkson W.A. Grudinin A.B. 《Quantum Electronics, IEEE Journal of》2003,39(8):987-994
We describe erbium-ytterbium co-doped fiber lasers in different free-running and tunable configurations. The lasers were cladding-pumped by high-power multimode diode sources. We compare pumping at 915 and 980 nm. With a free-running laser, we obtained slope efficiencies of up to 50% with 915-nm pumping and 38% with 980-nm pumping, with respect to absorbed pump power. We reached a double-ended output power of 16.8 W from the free-running laser. Thanks to a high rare-earth concentration and a small inner cladding area (possible with the high-brightness pump sources we used), the operating pump absorption of the fiber reached 8 dB/m. With such high absorption, short fibers with high nonlinear thresholds are possible even with cladding pumping. The tunable fiber laser had a tuning range from 1533 to 1600 nm and emitted 6.7 W of output power at 1550nm in a high-brightness, single-polarization, narrow linewidth beam. 相似文献
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根据激光三能级速率方程理论,考虑抽运光聚焦的空间分布,建立三维DPAL速率方程组的理论模型,结合激光系统运行的边界条件,通过数值方法,对模型进行求解,对端面抽运铷蒸气激光器的输出特性进行了详细分析,包括抽运光聚焦光斑半径、聚焦位置、蒸气池长度等参量对模式匹配效率、阈值抽运功率和斜率效率的影响。在模式匹配最佳时,计算了对介质长度对激光输出和阈值的影响。根据抽运光功率,以获得最大激光输出功率为目标,给出了激光器系统的优化参数,包括介质长度、抽运光聚焦在介质中的聚焦位置、输出耦合反射率。 相似文献
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基于大模面积双包层Er3+/Yb3+共掺光纤,采用P-F腔结构,详细研究了工作温度、光纤弯曲对泵浦吸收和激光输出性能的影响。结果表明:随着泵浦功率的增大,输出光谱的模式逐渐增多;泵浦源的工作温度决定其输出光谱特性,进而影响光纤激光器的输出效果;光纤不同激光模式对应不同光纤弯曲损耗,当弯曲半径减小到一定程度时,多模输出变成单模输出,由此提高输出光束质量。 相似文献
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为了优化高功率板条激光器的光束质量, 采用提高单侧基模光束的尺寸来限制腔内部分高阶模式振荡的方法, 针对半导体侧面抽运板条激光器, 测量了激光器在抽运状态下水平和竖直方向热焦距, 建立了热透镜等效模型, 并以平-平腔为参考, 设计了水平和竖直方向单侧基模尺寸均会扩大的平-凹腔。验证了对于激光介质截面尺寸固定的板条激光器, 扩大单侧基模尺寸可以限制高阶模式从而优化光束质量, 并提出了进一步优化板条激光器性能的研究方法。结果表明, 当平-凹腔的腔长为370mm时, 输出功率为59.9W, 水平方向M2因子由平-平腔的115.6显著优化至32.9, 竖直方向M2因子由116.4显著优化为60.9。该研究对于板条激光器获得高质量输出及相关应用有实际意义。 相似文献
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Effects of high density pumping on relaxation oscillations and mode spectra are investigated in LiNdP4 O12 (LNP) lasers. It is shown that high density pumping reduces the spatial population inhomogenuity, which is due to periodic inversion saturation by a first lasing mode in the crystal, and results in spontaneous single longitudinal mode oscillations even at high excitation rates. Physical interpretations are given for single-mode operations on the basis of Auger recombination (annihilation) process for 1.048 and 1.32 μm quantums in LNP lasers. An effective diffusion parameter of excited states is shown in an increase with absorbed pump power density through the Auger process. Observed relaxation oscillation waveforms, which disagreed with the traditional laser dynamic theory, are found to be explained well by the rate equations, including the effective diffusion constant. 相似文献
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On fluctuations and transients in injection lasers 总被引:1,自引:0,他引:1
A new computer model of the semiconductor injection laser is described. The electron-photon interactions are introduced using a Monte Carlo technique in combination with multimode rate equations to compute laser output versus time and to compute output power probability density. Laser turn-on initially in a side mode, followed by evolution to the normal equilibrium modal power distribution, is shown to be intrinsic and a natural consequence of fluctuations in the modal powers at the moment the laser passes through threshold. Calculations of fluctuations in the equilibrium power levels show that occasional dropouts of the main-mode power are also a natural consequence of electron-photon interactions. Reduction in equilibrium fluctuations and in turn-on fluctuations can be achieved by increasing the laser power-output level, by increasing the mirror reflectivities, and by decreasing the laser length. This work indicates that conventional injection lasers must be operated at or above the 1 mW level in order to assure an error rate of 10-9in digital systems. The well-known transition from thermal-noise statistics below threshold to Poisson statistics well above threshold is still evolving in the 0.5-2 mW region in the injection laser. 相似文献
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大模场光纤可以降低纤芯功率密度及提高非线性效应的阈值,是进一步提高光纤激光器功率的重要技术途径,但随着纤芯的增大,光纤中将产生多横模运转,降低光束质量。对国内外大模场光纤激光器中的高阶模抑制技术的研究进展进行详细的介绍。对大模场光纤激光器模式控制的发展前景进行了展望。 相似文献
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We present a detailed theoretical and experimental study of the development of the EM field in pulsed, passively Q-switched solid-state lasers. We solve the rate equations separately for the gain medium and a passive Q-switch, thus accounting for the beam propagation and profile variations between them. Our model enables us to follow the pulse formation from a randomly generated seed EM field, thus monitoring the instantaneous beam pattern. The rate equations used include excited-state absorption in saturable absorber as well as the pumping term. The latter proves to be important when analyzing the beam profiles when passive Q-switching is used. In the case of stronger pumping, the formation of the second laser pulse is observed and shows mode structure characteristic of higher order Laguerre-Gaussian beams. Theoretical results are compared with experiment for three different types of laser resonators. Positive-branch unstable resonators with an ordinary and a super-Gaussian output mirror were studied in order to obtain top-hat beam profile. A plano-concave stable resonator was used as a reference. The calculated beam profiles and temporal developments are in good agreement with the experimental results which proves that the presented computational method can be used to predict the performance of other resonator designs. 相似文献
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基于1S0能级的Pr3+:ZBLAN光纤上转换紫外激光的数值模拟 总被引:2,自引:0,他引:2
在Pr3 ∶ZBLAN光纤中,运用粒子数速率方程理论,研究用586 nm和335 nm连续激光双光子激发4f组态最高能级1S0,以1S0和3F4为激光上下能级实现250 nm上转换紫外激光的动力学行为,得到阈值抽运功率、激光输出功率、斜率效率和最佳光纤长度等激光参数。结果表明,阈值抽运功率随光纤长度增加而增大,斜率效率随光纤长度增加而减小,光纤较短时,无法获得较高输出功率。掺杂浓度越大则阈值抽运功率越小,斜率效率越大。在选取的特定条件下,斜率效率最高可达16.7%。 相似文献
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An analytic model of diode lasers applicable to both the lasing and the nonlasing states is described. For these homogeneously broadened devices, spectral envelope widths for TE00 and TM00 modes are related to power in each modal family and are shown to depend critically on spontaneous emission coupling into the transverse modes. Thus, lasers with real-refractive index waveguiding (and associated weak spontaneous emission coupling) operate single longitudinal mode above threshold, whereas gain-guided devices run multimode. After connecting gain and spontaneous emission, a charge conservation equation, containing optical power in the form of a stimulated emission term, pumping current, spontaneous emission, and spectral width, is derived. These equations are then demonstrated to suffice for determination of the completeL versusI characteristic. For lasers in which both charge and mode confinement exist, such as the buried heterostructure (BH) and channelled-substrate narrow stripe (CNS) types, it is shown that both TM00 power and spectral envelope width approach limiting values at threshold, whereas TE00 mode power grows in conjunction with TE00 spectral envelope narrowing. 相似文献
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大功率固体激光器高效率光纤耦合 总被引:5,自引:2,他引:5
光束质量参数对大功率固体激光器光纤耦合系统的设计起着关键作用。大功率固体激光器输出的为多模激光束,引入等效基模光束来计算多模激光束的光束质量是一种有效的方法,并定义包含光斑能量98%的光斑半径为束宽,以此计算多模激光束的光束质量,是准确有效的。结合大功率固体激光器的光纤耦合原理和光束变换理论设计了高效耦合系统,并对系统内透镜的通光孔径及焦距等参量做了数值优化。实验证明,此光纤耦合系统能够进行大功率固体激光高效率耦合,成功地实现了输入功率为2000W时,耦合效率大于94%的激光输出,并给出了光纤耦合的效率曲线及分析。 相似文献
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