Direct Modulation Properties of 1.55- μm InGaAsP/InP Microring Lasers

The modulation properties of 1.55-mum InGaAsP/InP microring lasers are investigated using a multimode rate equation model. A detailed study, with respect to Q-factor and extinction ratio calculations, is carried out as a function of different microring's key design and operating parameters. The modulator's performance study shows the possibility for a successful operation at a bit rate of 2.4 Gb/s for radii between 30 and 50 mum and proper values for the bus waveguide reflectivity.     

InAs–InP (1.55- μm Region) Quantum-Dot Microring Lasers

In this letter, we demonstrate electrically pumped continuous-wave lasing at room temperature in microring lasers, which employ a quantum-dot gain medium. Lasing occurs in the important 1.55-mum telecom wavelength range. The 2-mum-wide ring waveguides are made from InGaAsP-InP (100) material suitable for active-passive photonic integrated circuits. Lasing in rings down to 22 mum in diameter is found, with a threshold current of 12.5 mA.     

Low-Frequency Relative Intensity Noise due to Nonlinear Mode Competition in InGaAsP–InP Microring Lasers

An enhanced low frequency relative intensity noise due to mode hopping induced from the asymmetric gain suppression in InGaAsP–InP microring lasers, is observed experimentally for the first time. The experimental results are in good agreement to those predicted by a multimode model based on the rate equation approximation accounting for both symmetric and asymmetric nonlinear gain suppression.     

Effect of Growth Temperature on InP QD Lasers

We describe the effect of growth temperature on the optical absorption, gain, and threshold current density of 730-nm emitting, metal–organic vapor phase epitaxy (MOVPE) grown, InP–AlGaInP quantum-dot lasers. Decreasing the growth temperature from 750 $^{circ}hbox{C}$ to 690 $^{circ}hbox{C}$ leads to an increase in ground state absorption, while sufficient optical gain and low 300 K threshold current density is obtained in the growth temperature window between 710 $^{circ}hbox{C}$ and 730 $^{circ}hbox{C}$ . Wider (16 nm compared to 8 nm) interlayer barriers lead to lower threshold current density with 300 K values as low as 165 $hbox{Acm}^{-2}$ for 2-mm-long lasers with uncoated facets.      

DFB Lasers With Deeply Etched Vertical Grating Based on InAs–InP Quantum-Dash Structures

Distributed feedback lasers with first-order vertical grating based on AlInGaAs-InAs-InP quantum-dash lasers were fabricated by electron beam lithography and Cl₂-Ar reactive ion etching with an electron cyclotron resonance source. Low threshold currents and single-mode operation with sidemode suppression ratios of 48 dB and a direct modulation bandwidth of 5.5 GHz were demonstrated     

InGaAsP／InP激光器非平面液相外延生长的研究

本文叙述了用于制作 InGaAsP/InP 半导体激光器的非平面液相外延工艺。讨论了各种因素对非平面液相外延生长的影响。在 InP 衬底上和刻有沟槽的 InGa-AsP/InP 外延片上成功地生长出了高质量外延层。用该外延片制作的激光器在室温连续工作条件下典型阈值电流30mA,典型输出功率为10mW。最高激射温度为115℃。     

Theoretical Investigation of Polarization-Insensitive Multimode Interference Splitters on Silicon-on-Insulator

An ultracompact polarization-insensitive 1times2 multimode interference (MMI) splitter based on silicon-on-insulator is investigated theoretically. The impact of the insulator index on the size of the MMI and the polarization-dependent performance is analyzed. A polarization-insensitive 1times2 MMI splitter of 4 mum by 16.5 mum is shown as an example. Relaxed tolerances on MMI width (> plusmn100 nm) and length (> plusmn0.7 mum) are obtained for both polarizations while the polarization differential loss is kept in range of 0.1 dB and its excess loss is kept below 0.5 dB. In addition, a wide operation wavelength window of 150 nm is obtained for both polarizations as well.     

Polarization Dynamics of Current-Modulated Vertical-Cavity Surface-Emitting Lasers

We study the dynamics of vertical-cavity surface-emitting lasers (VCSELs) with direct current modulation in the framework of a model for index-guided VCSELs that takes into account two orthogonal linear polarizations. We analyze the effect of current modulation near the polarization switching (PS) of type I, from the high to the low frequency polarization, and near the PS of type II, from the low to the high frequency polarization. We find that the oscillations of the total power are as those of a single-mode laser, unaffected by the underlaying polarization coexistence or polarization competition. We also study the small-signal modulation response in the Fourier domain, for modulation dc values near the PS point. Close to type I PS the response of the total power as well as the response of the orthogonal polarizations has the same functional dependency on the modulation frequency, and can be fitted by the response function of a single-mode laser. Close to type II PS, polarization competition is a significant process at low modulation frequencies. The polarization-resolved modulation response displays features at low frequencies that are not present in the response of the total power, which is as that of a single-mode laser. The dynamics becomes increasingly complex as the modulation amplitude grows, and there is multistability of solutions.     

Dynamics of Optically-Injected Semiconductor Lasers Using the Travelling-Wave Approach

The dynamics of optically-injected semiconductor lasers are of great practical interest for various applications such as chaotic signal transmission. For the first time, a method is presented to obtain a complete picture of the dynamics for optically-injected systems simulated with the travelling-wave model by investigating their trajectories. The method uses the distribution of intersection points of the trajectory on a PoincarÉ plane to distinguish between different dynamical states of the system. It is then applied to obtain stability maps for the reflected and transmitted light of three quarter-wave-shifted distributed-feedback lasers with different Bragg coupling coefficients and it is shown that, firstly, the dynamics are different for the reflected and transmitted light and, secondly, the locking bandwidth for the case with lower Bragg coupling coefficient is significantly increased. Both findings are in agreement with published results obtained by a different analysis.      

基于数字阵列雷达的同时多模式SAR 成像体制研究

数字阵列雷达(Digital Array Radar, DAR)用于合成孔径雷达(Synthetic Aperture Radar, SAR)成像能够同时完成多种成像模式,具有广阔的应用前景。该文首先对DAR 的基本硬件结构和工作原理进行介绍。在此基础上,结合数字波束形成(Digital BeamForming, DBF)技术,提出6 种可同时实现多模式SAR 成像的工作方式,并对各种工作方式给出了相应的新颖的成像模式。此外,以某种新颖的模式为例,给出了其系统设计的详细过程。最后通过仿真实验验证了该成像模式的有效性及正确性。      

磷化铟晶体材料的应用进展研究

回顾了磷化铟（ＩｎＰ）晶体材料的发展过程，介绍了磷化铟材料的多种用途和优越特性，展望了磷化铟材料在我国的发展前景。     

Dynamics and Temperature-Dependence of 1.3-μm GaInNAs Double Quantum-Well Lasers

We have measured the small-signal modulation response of 1.3-mum ridge waveguide GaInNAs double quantum-well lasers over a wide range of temperatures (25 degC-110 degC) and analyzed the temperature dependence of the modulation bandwidth and the various bandwidth limiting effects. The lasers have low threshold currents and high differential efficiencies with small temperature dependencies. A short-cavity (350 mum) laser has a modulation bandwidth as high as 17 GHz at room temperature, reducing to 4 GHz at 110 degC, while a laser with a longer cavity (580 mum) maintains a bandwidth of 8.6 GHz at 110 degC. We find that at all ambient temperatures the maximum bandwidth is limited by thermal effects as the temperature increases with current due to self-heating. The reduction and subsequent saturation of the resonance frequency with increasing current is due to a reduction of the differential gain and an increase of the threshold current with increasing temperature. We find large values for the differential gain and the gain compression factor. The differential gain decreases linearly with temperature while there is only a weak temperature dependence of the gain compression. At the highest temperature we also find evidence for transport effects that increase the damping rate and reduce the intrinsic bandwidth     

InP/InGaAs/InP双异质结双极晶体管技术研究

介绍了InP/InGaAs/InP双异质结双极晶体管(DHBT)材料生长、器件结构与设计、制作工艺和性能测试以及在振荡器中的应用等方面的研究.采用发射极-基极自对准工艺制作了InP/InGaAs/InP DHBT器件,发射极尺寸为1.5μm×10μm的器件小电流直流增益β约25,集电极-发射极击穿电压BVCEO≥10V,截止频率,ft和最高振荡频率,fmax分别为50和55GHz;     

InP/InGaAs/InP双异质结双极晶体管技术研究

介绍了InP/InGaAs/InP双异质结双极晶体管(DHBT)材料生长、器件结构与设计、制作工艺和性能测试以及在振荡器中的应用等方面的研究.采用发射极-基极自对准工艺制作了InP/InGaAs/InP DHBT器件,发射极尺寸为1.5μm×10μm的器件小电流直流增益β约25,集电极-发射极击穿电压BVCEO≥10V,截止频率,ft和最高振荡频率,fmax分别为50和55GHz;     

Analysis of InP Regrowth on Deep-Etched Mesas and Structural Characterization for Buried-Heterostructure Quantum Cascade Lasers

We investigated the effect of deep-etched mesa sidewall profile and oxide overhang length on the regrowth structural characteristics for buried- heterostructure (BH) quantum cascade lasers (QCLs) grown by metalorganic chemical vapor deposition (MOCVD). The relationship between etched mesa sidewall geometry, oxide overhang length, oxide thickness, and growth uniformity was examined and is extensively discussed. In particular, anomalous growth in the vicinity of the oxide edge resulting from insufficient oxide overhang length was identified and studied. An ideal ratio of mesa height to oxide overhang length between 2.5 and 3.0 is proposed and experimentally justified to yield satisfactory planar regrowths without anomalous growth. Mesas in the [ 0 1[` 1] ] [ 0 1\overline{ 1} ] direction with smoothly etched entrant profile yield a higher degree of growth uniformity than mesas in the [011] direction with the re-entrant profile.     

Analysis of the Double Laser Emission Occurring in 1.55-μm InAs–InP (113)B Quantum-Dot Lasers

In this paper, a theoretical model based on rate equations is used to investigate static and dynamic behaviors of InAs-InP (113)B quantum-dot (QD) lasers emitting at 1.55 mum. More particularly, it is shown that two modelling approaches are required to explain the origin of the double laser emission occurring in QD lasers grown on both, GaAs and InP substrates. Numerical results are compared to experimental ones by using either a cascade or a direct relaxation channel model. The comparison demonstrates that when a direct relaxation channel is taken into account, the numerical results match very well the experimental ones and lead to a qualitative understanding of InAs-InP (113)B QD lasers. Numerical calculations for the turn-on delay are also presented. A relaxation oscillation frequency as high as 10 GHz is predicted which is very promising for the realization of directly modulated QD lasers for high-speed transmissions.     

Experimental and Theoretical Study of InAs/InGaAsP/InP Quantum Dash Lasers

We present a combined theoretical and experimental analysis of InAs/InGaAsP/InP quantum dash lasers. Calculations using an 8 band k.p Hamiltonian show that electron states, due to the low effective mass and small conduction band offsets, are not confined in the dash in the case of dash-in-a-well structures and are only weakly confined in dash-in-a-barrier structures. The shape of the dashes leads to an experimentally observed enhancement of spontaneous emission (SE) and therefore of gain for light polarized along the dash long axis, with the measured SE enhancement in excellent agreement with the theoretical calculations. An analysis of the variation of the integrated spontaneous emission rate with total current and with temperature reveals that, despite the reduced dimensionality of the active region, the threshold current of these lasers, and its temperature dependence, remain dominated by Auger recombination.      

InGaAsP／InP双区共腔激光器的内部参数

根据《双区半导体激光器的稳定性理论》,分析了 InGaAsp/Inp 掩埋异质结构双区共腔激光器的实验结果,计算了这种器件的内部参数。结果表明:内部光耦合随着温度变化是改变器件工作状态的主要因素;阈值电流偏高与器件工艺相关的界面缺陷、结构漏电关系极大;结构漏电可以提高光输出功率。     

MOVPE生长1.3 μm无致冷AlGaInAs/InP应变补偿量子阱激光器研究

通过低压金属有机化学气相外延 (LP MOVPE)工艺生长了AlGaInAs应变补偿量子阱材料 ,通过X射线双晶衍射、光荧光、二次离子质谱的测试分析得到了材料生长的优化工艺参数 ,降低了材料中的氧杂质含量 ,得到了高质量AlGaInAs应变补偿量子阱材料 ,室温光致发光半宽FWHM =2 6meV。采用此外延材料成功制作了 1 3μm无致冷AlGaInAs应变量子阱激光器 ,器件测试结果为 :激射波长 :12 90nm≤ λ≤ 1330nm ;阈值电流 :Ith(2 5℃ )≤15mA ;Ith(85℃ )≤ 2 5mA ;量子效率变化 :Δηex(2 5～ 85℃ )≤ 1 0dB。     

Dynamics of Broad-Area Semiconductor Lasers With Short Optical Feedback

The dynamics of filamentations in broad-area semiconductor lasers with short optical feedback were numerically studied. Regular pulse packages similar to those observed in narrow-stripe edge-emitting semiconductor lasers were found as the feedback reflectivity is increased. However, the regular pulse packages consisted of a periodic envelope of the external cavity frequency and fine pulse trains of periodic filaments, which is different from the regular pulse packages observed in narrow-stripe edge-emitting semiconductor lasers. From the analysis for spatio-temporal near-field patterns, we found periodic undulations of the spatial and temporal filament sizes as the external mirror reflectivity was changed. We also investigated filtered optical feedback, where a part of the emitted beam is fed back into the laser cavity. The time-averaged near-field pattern was found to have a strong dependence on the feedback level in the case of spatial filtered optical feedback.