Threshold current of 670-nm AlGaInP strained quantum well lasers

By means of gain-current calculations we have examined the factors which determine the threshold current of compressively strained Ga_x In_1-xP/AlGaInP quantum well lasers for the various well width/composition (x) combinations which give a transition wavelength of 670 nm. In addition to valence band modifications we find that the increasing depth and decreasing width of the well are important in decreasing the current as the strain increases. We reveal the important role of well width fluctuations in devices with high compressive strain     

High-brightness AlGaInP 573-nm light-emitting diode with a chirpedmultiquantum barrier

A novel chirped multiquantum barrier (CMQB) structure was used for AlGaInP light-emitting devices. We have theoretically studied the blocking efficiency of the CMQB structure and found that the CMQB structure is more effective in blocking the electron wave than the conventional uniform multiquantum barrier (UMQB) structure. AlGaInP light emitting diodes (LEDs) with the CMQB structure and the UMQB structure were both fabricated and compared. It was found that the luminescence intensity of the AlGaInP CMQB LED is larger and the intensity distribution of the AlGaInP CMQB LED is more uniform than the AlGaInP UMQB LED. The intensity-current measurement also shows that the electroluminescence intensity of the AlGaInP CMQB LED starts to saturate at a higher injection current     

High-power AlGaInP three-ridge type laser diode array

A three ridge type GaInP/AlGaInP visible light emitting laser diode array grown by AP-OMVPE has been achieved. A pulsed maximum output power of 108 mW is obtained from this laser array without the use of facet coatings. The pulsed threshold current is 290 mA and the external differential efficiency is 0.75 W/A     

Broad area phase-locked superlattice barrier quantum well laser diode

The lateral coherence of an extremely broad-area laser diode is examined. The device was fabricated using molecular-beam epitaxy (MBE). For a 350- mu m-wide mesa laser, a single-lobed phase-locked narrow beam was obtained owing to the use of a high-uniformity quantum well graded-index waveguide separate confinement heterostructure (GRIN-SCH) with a short-period (AlGaAs)(GaAs) superlattice MBE-fabricated barrier layer.<>     

AlGaInP/GaInAs strained quantum well lasers

AlGaInP cladding layers have been applied for the first time to GaInAs strained quantum well lasers oscillating around 0.98 mu m. The device has lower threshold current and larger T/sub 0/ than a device with GaInP cladding layers. This was expected from a larger bandgap difference between active and cladding layers.<>     

High-performance 670-nm AlGaInP/GaInP visible strained quantum welllasers

We have grown high-performance AlGaInP/GaInP visible (670 mn) strained quantum well lasers by low-pressure metalorganic chemical vapor deposition. With AlInP cladding layer, a high-power AlGaInP/GaInP visible laser diode is achieved. Its threshold current is about 30 mA. The output power of this laser diode can maintain, at least, at 32 mW under continuous-wave (CW) operation at room temperature. High slope efficiency (0.8 mW/mA) and differential quantum efficiency (0.87) can be achieved. To improve beam quality, AlGaInP/GaInP visible lasers with and without depressed index cladding layer are theoretically and experimentally studied. From experimental results, the transverse beam divergence can be reduced from 41.4° to 26.2° while maintaining a low threshold current (from 36 mA to 46 mA). By using the transfer matrix method, our theoretical calculations are in good agreement with the experimental results     

A graded index single quantum well bistable laser

The authors report the first implementation of a buried heterostructure DOES (double heterostructure optoelectronic switch), which incorporates the principles of graded-index, single-quantum-well (GRIN SQW) lasers. Continuous operation and a small signal optical bandwidth of 1.5 GHz were obtained when biased into the on-state. This is consistent with the bond pad side employed. This GRIN SQW DOES laser, fabricated in two-terminal BH form, has been shown to have properties commensurate with the growth and processing parameters employed. Although limited to two-terminal operation, performance is comparable to existing devices with similar designs     

Kink and power saturation of 660-nm AlGaInP laser diodes

We analyze kink and power saturation phenomena of high power 660-nm laser diodes for DVD-R/RW experimentally. Power-current (P-I) and voltage-current (V-I) characteristics of laser diodes with different cavity lengths were measured. Using these results and thermal resistances, temperature rises caused by self-heating (/spl Delta/T) and the dependence of slope efficiencies on the temperature rise (Se-/spl Delta/T) were calculated. The slope efficiencies decreased linearly with /spl Delta/T and their gradients showed the same value regardless of the cavity length, while they had no systematic dependence on the current. The kinks occurred at the same /spl Delta/T of 30/spl deg/C regardless of the cavity length, while they occurred at different currents. These results indicate that the temperature rise caused by the self-heating is a key parameter for the kink and the saturation power. A method is proposed to calculate the kink and the saturation power using the gradient (Se-/spl Delta/T) and the kink temperature.     

Dual-frequency GaAs/InGaP laser diode with a GaAsSb quantum well

The results of investigation of a metal-organic-vapor-phase-epitaxy-grown GaAsSb/GaAs/InGaP laser structure are presented. Steady two-band generation caused by spatially direct and indirect optical transitions is obtained. Observation of the sum frequency shows the effective intracavity mixing of modes in semiconductor lasers of such a type.     

A 357.9 nm GaN/AlGaN multiple quantum well ultraviolet laser diode

Ultraviolet(UV)and deep-UV light emitters are prom-ising for various applications including bioagent detection,wa-ter and air purification,dermatology,high-density optical stor-age,and lithography.However,to achieve shorter UV laser di-odes(LDs),especially for the LDs with lasing wavelength less than 360 nm,requires high AlN mole fraction AlGaN clad-ding layer(CL)and waveguide(WG)layers,which usually leads to generate cracks in AlGaN epilayer due to lack of lat-tice-matched substrates.Meanwhile,due to high resistivity of high AlN mole fraction Mg doped AlGaN layers,only few groups have reported GaN-based LDs with emission wavelength shorter than 360 nm[1?8],and up to now,there is no room temperature continuous-wave(CW)operation UV LDs with a lasing wavelength shorter than 360 nm ever repor-ted.Previously,we have reported a UV LD with lasing wavelength of 366 nm[9].In this paper,a higher AlN mole frac-tion of AlGaN WG layers is employed to shorten the LD emis-sion wavelength to less than 360 nm.A lasing wavelength of 357.9 nm is achieved.     

Power output of 650-nm self-pulsating AlGaInP laser diodes foroptical storage applications

Self-pulsating laser diodes operating at a wavelength of 650 nm are required in optical storage devices. Pulsation can be achieved by including saturable absorbing quantum wells in the p-doped cladding layer of an AlGaInP laser. A rate equation model of this kind of device is used to analyze the power output of the pulses by varying the cavity length and the absorber quantum-well configuration. Results indicate that certain performance tradeoffs occur between the power output and other characteristics that are subject to optical storage device constraints     

642-nm AlGaInP laser diodes with a triple tensile strain barriercladding layer

For the first time, tensile strain barrier cladding (TSBC) layers were used in AlGaInP laser diodes (LDs). It was found that the TSBC layers can provide a better optical confinement and a better carrier confinement. AlGaInP LDs with and without the TSBC layers were both fabricated. It was found that the 48-mA threshold current of the 5 μm×800 μm gain-guided triple TSBC AlGaInP LD is lower than the 56-mA threshold current of the conventional AlGaInP LD with the same physical size. The characteristic temperature T₀ of the triple TSBC AlGaInP LD (i.e., 117 K) is also higher than the conventional AlGaInP LD (i.e., 99 K)     

Small-signal performance of a quantum well diode

We study a small-signal performance of a quantum well (QW) diode with triangular emitter and collector barriers providing thermionic electron transport. Analytical expression for the QW diode admittance is obtained from the rigorous self-consistent small-signal analysis. Frequency dependence of the admittance is determined by a characteristic time of recharging of the QW, which is a strong function of temperature and parameters of the QW diode. Conductance as a function of temperature shows a local maximum corresponding to a resonance between a probe signal and recharging processes. Capacitance of the QW diode depends critically on the efficiency of the electron transport through the QW, and can significantly exceed all geometric capacitances associated with the device structure. Experimental data on conductance and capacitance of the QW diode as functions of temperature and frequency can be used to extract the parameters of the QW, such as QW recombination velocity, ionization energy, etc. Analytical analysis of transient currents in the QW diode allows a transparent explanation why an incremental charge-partitioning technique fails to calculate the capacitance even in the low-frequency limit     

All-optical active switch using a multiple quantum well nonlinearetalon as a laser diode mirror

A GaAs/AlGaAs multiple quantum well nonlinear etalon with a Bragg reflector was used as a feedback mirror of an external cavity laser diode. The laser oscillation was switched on/off by an external control light with high contrast ratio of 30:1     

Integrated quantum well intersub-band photodetector and lightemitting diode

The authors propose and demonstrate the integration of a quantum well intersub-band photodetector (QWIP) and a light emitting diode (LED) for making large two-dimensional focal plane arrays for thermal imaging applications. The newly developed QWIP technology is combined with the well established LED technology both based on GaAs and related epitaxially grown alloys, such as AlGaAs and InGaAs     

单量子阱激光器小信号调制时的啁啾噪声

量子阱激光器具有良好的小信号调制频率响应 ,能作为高速光通信光源采用直接调制方式进行信号传输。与普通半导体激光器一样 ,直接调制将引起啁啾 ,从而影响光纤通信系统的性能。文中对小信号调制下单量子阱激光器的啁啾特性进行了研究和分析。得出了啁啾幅度和啁啾相位与调制频率的关系。对考虑与不考虑啁啾两种情况下 ,光脉冲在常规光纤中传输时的色散特性进行了模拟分析 ,发现了啁啾对系统的高阶色散有较大影响     

A 980-nm band laser diode pump source with a detuned wavelength of1000 nm for praseodymium-doped fiber amplifiers

By using practical high-power 980-nm band laser diodes, efficient direct pumping for a praseodymium-doped fiber amplifier (PDFA) is achieved. The lasing wavelength is detuned from 980 to 1000 nm by selective optical feedback from a fiber grating     

Correlation between dark current RTS noise and defects for AlGaInP multiple-quantum-well laser diode

推导了AlGaInP多量子阱LD器件暗电流RTS 噪声与缺陷相关性模型,实验结果表明暗电流RTS 噪声由有源区异质结界面载流子数涨落引起。根据相关性模型,确定了缺陷类型,定量确定了缺陷能级。分析了暗电流RTS 噪声功率谱密度的转角频率。实验结果和理论预测一致。本文结论提供一种确定AlGaInP多量子阱LD器件有源区深能级的有效方法。     

1.5 mu m tensile-strained single quantum well 20-wavelength distributed feedback laser arrays

Tensile-strained single quantum well 20-wavelength distributed feedback laser arrays have been fabricated with a wide wavelength span of 56 nm in the 1.5 mu m wavelength region. The light output is TM-polarised and the average threshold current is 22.8 mA for an 875 mu m long array. A minimum laser linewidth of 180 kHz is measured by a delay self-heterodyne method.<>