Low threshold current density operation of GaInNAs quantum welllasers grown by metalorganic chemical vapour deposition

A metal organic chemical vapour deposition grown GaInNAs quantum well laser emitting at 1.25 μm is reported. The lowest threshold current density obtained by 50 μm wide stripe lasers was 340 A/cm² for a cavity length of 1420 μm. Which is almost comparable to the lowest value reported for GaInNAs lasers grown by molecular beam epitaxy. The threshold current density per well was 170 A/cm², which is the lowest threshold value reported to date     

Low threshold current density 1.5 mu m GaInAs/AlGaInAs graded-index separate-confinement-heterostructure quantum well laser diodes grown by metal organic chemical vapour deposition

A low threshold current density of 640 A/cm/sup 2/ was obtained in a 1.5 Gmm GaInAs/AlGaInAs multiple quantum well laser diode, grown by metal organic chemical vapour deposition, with continuously graded-index separate-confinement heterostructure. An internal waveguide loss of 14 cm/sup -1/ and internal quantum efficiency of 59% were obtained, which are comparable to those of GaInAs/GaInAsP quantum well laser diodes.<>     

Low threshold current AlGaAs/GaAs rib-waveguide separate-confinement-heterostructure distributed-feedback lasers grown by metalorganic chemical vapor deposition

AlGaAs/GaAs rib-waveguide separate-confinement-heterostructure (SCH) distributed-feedback (DFB) lasers emitting at 880 nm were fabricated by a two-step atmospheric pressure metalorganic chemical vapor deposition (MOCVD) growth technique. A CW threshold current as low as 18 mA and an output power of more than 10 mW per facet at room temperature were obtained. Also, single longitudinal and fundamental transverse modes were maintained up to more than twice the threshold current level.     

Modeling and simulation of InAs/GaAs quantum dot lasers

Based on the analysis of carrier dynamics in quantum dots (QDs), the numerical model of InAs/GaAs QD laser is developed by means of complete rate equations. The model includes four energy levels and among them three energy levels join in lasing. A simulation is conducted by MATLAB according to the rate equation model we obtain. The simulation results of PI characteristic, gain characteristic and intensity modulation response are reasonable. Also, the relations between the left facet reflectivity of laser cavity and threshold current as well as modulation bandwidth are studied. It is indicated that the left facet reflectivity increasing can result in reduced threshold current and improved modulation bandwidth, which is in accordance with experimental results. The internal mechanism of QD lasers is fully described with the rate equation model, which is helpful for QD lasers research.     

高性能InAs/GaAs量子点外腔激光器

为了获得高性能的量子点外腔激光器(ECL),利用InAs/GaAs量子点Fabry-Perot(FP)腔激光器研制了光栅外腔可调谐ECL。对InAs/GaAs量子点ECL进行了一系列的性能测试,主要包括单模稳定性测试、单模调谐范围测试、阈值电流密度测试、无跳模连续调谐测试和输出功率测试。在室温条件下获得了24.6nm的连续调谐范围,覆盖波长从999.2nm到1 023.8nm,并且实现了波长无跳模连续调谐。在调谐范围内最低阈值电流密度为1 525A/cm2,而且在中心波长处获得的单模输出功率为15mW,单模边模抑制比(SMSR)高达35dB。研究结果表明,通过构建光栅外腔可以实现高性能的InAs/GaAs量子点ECL。     

Broad-area InAs/GaAs quantum dot lasers incorporating intermixed passive waveguide

InAs/GaAs quantum dot lasers incorporating passive waveguide created by post-growth intermixing processing have been studied. Emission wavelength of the passive section shows relative blueshift as high as 135 nm with respect to the emission wavelength of the active section. Intrinsic losses in the section formed by the intermixing are very small. Broad-area lasers with 100 mum stripe width incorporating intermixed section have demonstrated improvements in far-field pattern under both pulsed and continuous wave pumping current     

Low threshold current density 1.3 /spl mu/m InAs/InGaAs quantum dot lasers with InGaP cladding layers grown by gas-source molecular-beam epitaxy

InAs/InGaAs quantum dot lasers with InGaP cladding layers grown by gas-source molecular-beam epitaxy (MBE) are reported. The laser emits 1.296 /spl mu/m light output and demonstrates a very low threshold current density of 111 A/cm/sup 2/. This is the lowest reported value of GaAs-based 1.3 /spl mu/m quantum dot lasers with InGaP cladding layers.     

1.43 /spl mu/m InAs bilayer quantum dot lasers on GaAs substrate

An edge emitting quantum dot (QD) laser at 1430 nm is demonstrated with a structure grown by molecular beam epitaxy on GaAs substrate. The active region is based on three InAs bilayer QDs embedded in a conventional AlGaAs/GaAs waveguide. The threshold current density is 134 A/cm/sup 2/. Output power of 23 mW per facet is achieved.     

Low threshold current GaAs/GaAlAs GRIN-SCH stripe lasers grown by OMVPE

The letter describes the characteristics of stripe lasers formed in GaAs/GaAlAs single-quantum-well graded-composition separate-confinement heterostructures (GRIN-SCH) grown by low-pressure organometallic vapour phase epitaxy (LP-OMVPE). We show that the low threshold current density that has been achieved with the GRIN-SCH structure allows low threshold currents (38 mA) to be achieved in a simple gain-guided stripe-geometry laser. These low thresholds have been obtained without resorting to a complex nonplanar (lower yield) technology, and it is shown that the good uniformity offered by OMVPE is maintained through to the mounted device stage.     

InAs/InP量子点激光器制备工艺研究

报道了通过化学湿刻蚀制备窄脊条InAs/InP量子点激光器的方法。激光器脊条主要是由半导体材料InGaAs和InP构成,通过选择合适配比的H2SO4∶H2O2∶H2O和H3PO4∶HCl腐蚀溶液和InP的腐蚀方向,在室温下选择性地腐蚀了InGaAs和InP,获得了窄脊条宽为6μm的量子点激光器。此激光器能够在室温连续波模式下工作,激射波长在光纤通信重要窗口1.55μm,单面最大输出功率超过12mW。     

Dynamics of InAs/GaAs quantum dot lasers epitaxially grown on Ge or Si substrate

Growing semiconductor laser sources on silicon is a crucial but challenging technology for developing photonic integrated circuits(PICs).InAs/GaAs quantum dot(Qdot)lasers have successfully circumvented the mismatch problem betweenⅢ–Ⅴmaterials and Ge or Si,and have demonstrated efficient laser emission.In this paper,we review dynamical characteristics of Qdot lasers epitaxially grown on Ge or Si,in comparison with those of Qdot lasers on native GaAs substrate.We discuss properties of linewidth broadening factor,laser noise and its sensitivity to optical feedback,intensity modulation,as well as mode locking operation.The investigation of these dynamical characteristics is beneficial for guiding the design of PICs in optical communications and optical computations.     

Low threshold current high-temperature operation of InGaAs/AlGaAsstrained-quantum-well lasers

The authors report improved high-temperature characteristics for In_0.2Ga_0.8As strained-quantum-well ridge waveguide lasers with an optimized cavity design. They have fabricated In_0.2 Ga_0.8As lasers that operate CW at up to 220°C with over 9-mW output power. At 200°C the threshold current is as low as 15.9 mA for a 400-μm-long laser with 35/98% reflectivity facets. Optimization of the laser cavity also improves the high-temperature operation of quantum-well lasers in other material systems; GaAs quantum well lasers that operate at up to 220°C CW have been fabricated     

Annealing behavior of InAs/GaAs quantum dot structures

We investigate the annealing behavior of InAs layers with different thicknesses in a GaAs matrix. The diffusion enhancement by strain, which is well established in strained quantum wells, occurs in InAs/GaAs quantum dots (QDs). A shift of the QD luminescence peak toward higher energies results from this enhanced diffusion. In the case of structures where a significant portion of the strain is relaxed by dislocations, the interdiffusion becomes negligible, and there is a propensity to generate additional dislocations. This results in a decrease of the QD luminescence intensity, and the QD peak energy is weakly affected.     

Low frequency noise spectroscopy in InAs/GaAs resonant tunneling quantum dot infrared photodetectors

We have studied the temperature dependence of low-frequency noise in InAs–GaAs resonant tunneling quantum dot infrared photodetectors (T-QDIPs). The noise in these devices has been investigated in the temperature range of 78–300 K. The noise spectrum showed a weak Lorentzian component superimposed upon the 1/f^γ spectrum. The change in the cut-off frequency of the Lorentzian was analyzed as a function of temperature. The activation energy of the trap associated with this Lorentzian was obtained as 0.155 eV, which is in good agreement with the energy of the lowest energy state in the quantum dot.     

Reliability study of InAs/InGaAs quantum dot diode lasers

Ridge-waveguide lasers with an InAs/InGaAs quantum dot active region have been subjected to accelerated ageing at 65 and 85/spl deg/C. No sudden failure was found during the 2070 h test. Activation energy of 0.79 eV was estimated, suggesting the 40/spl deg/C-lifetime >10/sup 6/ h.     

Temperature dependence of threshold current of GaAs quantum well lasers

The radiative recombination rate in a quantum well structure is calculated using a constant density of states and the k-selection rule. This calculation shows that the threshold current of a GaAs quantum well laser has low temperature sensitivity (T0 ? 330 K for T > 300 K).     

Lateral electronic transport in short-period InAs/GaAs superlattices at the threshold of quantum dot formation

Temperature dependences of resistance at 0.7 K<T<300 K, the Hall and Shubnikov-de Haas effects in magnetic fields of up to 40 T, photoluminescence (PL), and morphology of a heterointerface (using an atomicforce microscope) of short-period InAs/GaAs superlattices were investigated. The investigations were carried out for a region of subcritical and critical thickness Q=2.7 monolayers (ML) of InAs. Upon exceeding the critical thickness, the self-organized growth of InAs quantum dots (QDs) set in. The formation of QD layers upon exceeding the critical thickness of InAs Q=2.7 ML is accompanied by a transition of conductivity from metallic to hopping. It is found that at InAs layer thicknesses of Q=0.33 ML and Q=2.0 ML, the PL intensities and electron mobilities in the structures have clearly pronounced maxima. Anisotropy of conductivity, which depends on the thickness of the deposited InAs layers, was observed.     

Optimisation of a-factor for quantum dot InAs/GaAs fabry-perot lasers emitting at 1.3 /spl mu/m

Dynamic measurements of the Henry factor alpha_H of InAs/GaAs Fabry-Perot lasers are compared for 3-, 5- and 10-QD layers. While alpha_H dramatically increases with the bias current for 3- and 5-QD stacks, it only amounts to <4 for the 10-layer stack at high currents, a value similar to that of QW-lasers     

Investigation into the InAs/GaAs quantum dot material epitaxially grown on silicon for O band lasers

InAs/GaAs quantum dot(QD)lasers were grown on silicon substrates using a thin Ge buffer and three-step growth method in the molecular beam epitaxy(MBE)system.In addition,strained superlattices were used to prevent threading disloca-tions from propagating to the active region of the laser.The as-grown material quality was characterized by the transmission electron microscope,scanning electron microscope,X-ray diffraction,atomic force microscope,and photoluminescence spectro-scopy.The results show that a high-quality GaAs buffer with few dislocations was obtained by the growth scheme we de-veloped.A broad-area edge-emitting laser was also fabricated.The O-band laser exhibited a threshold current density of 540 A/cm² at room temperature under continuous wave conditions.This work demonstrates the potential of large-scale and low-cost manufacturing of the O-band InAs/GaAs quantum dot lasers on silicon substrates.