1.55μm张应变InGaAsP/InGaAsP量子阱偏振不灵敏半导体光放大器的优化设计

优化设计了1.55μm InGaAsP/InGaAsP张应变量子阱偏振不灵敏半导体光放大器的结构.利用k*p方法计算了多量子阱的价带结构,计算中考虑了6×6有效质量哈密顿量.从阱宽、应变、注入载流子密度等方面计算了量子阱模式增益的偏振相关性.     

Reduced turn-on delay time in 1.3-/spl mu/m InGaAsP-InP n-type modulation-doped strained multiquantum-well lasers with a buried heterostructure

A reduction in both the threshold current and carrier lifetime is demonstrated, for the first time, in an n-type modulation-doped InGaAsP strained multiquantum well laser with a buried heterostructure. Threshold current and carrier lifetime is reduced by 10% and 15%, respectively, as compared with a undoped MQW laser, which results in a 35% decrease in the turn-on delay time. This confirms the suitability of this type of laser for use as a light source for high-density parallel optical interconnection.     

全固源分子束外延InAsP/InGaAsP多量子阱1.55μm激光器

利用新型全固源分子束外延技术 ,对 1 .5 5 μm波段的 In As P/ In Ga As P应变多量子阱结构的生长进行了研究。实验表明 ,较低的生长温度或较大的 / 束流比有利于提高应变多量子阱材料的结构质量 ,而生长温度对材料的光学特性有较大的影响。在此基础上生长了分别限制多量子阱激光器结构 ,制作的氧化物条形宽接触激光器实现了室温脉冲工作 ,激射波长为 1 5 63 nm,阈值电流密度为 1 .4k A/ cm2 。这是国际上首次基于全固源分子束外延的 1 .5 5 μm波段 In As P/ In Ga As P多量子阱激光器的报道     

Hole distribution in InGaAsP 1.3-μm multiple-quantum-well laserstructures with different hole confinement energies

We have investigated the hole distribution in strained InGaAsP multiple-quantum-well (MQW) structures by direct hole transport measurements with time-resolved photoluminescence spectroscopy. The results show that the hole transport time over the MQW primarily depends on the hole confinement energy in the wells and increases sharply with the well depth. A simple thermionic emission model indicates that the heavy holes escape predominantly over the light-hole barrier edge for strain-compensated MQW structures. The results are corroborated with observed laser performance data     

Enhanced relaxation oscillation frequency of 1.3 μmstrained-layer multiquantum well lasers

Dependence of relaxation oscillation frequency (f_r) on the bandgap wavelength of InGaAsP barrier layers (λ_g ^b) and number of quantum wells (N_w) were investigated for the first time, for 1.3 μm InGaAsP/InGaAsP compressively strained multiquantum well (MQW) lasers. 1.3 times higher f_r was confirmed for strained-layer MQW lasers with large N _w (N_w⩾7) and wide bandgap barrier layers (λ_g^b=1.05 μm) at the same injection level, compared with unstrained MQW lasers having the same well thicknesses and the same emitting wavelength. This enhancement mainly results from increased differential gain due to strain effects separated from the quantum-size effect     

1.3μm低阈值InGaAsP/InP应变补偿MQW激光器的LP-MOCVD生长

报道了用低压金属有机物化学气相淀积（ＬＰ－ＭＯＣＶＤ）方法外延生长ＩｎＧａＡｓＰ／ＩｎＰ应变补偿多量子阱结构。用此材料制备的掩埋异质结（ＢＨ）条形结构多量子阱激光器具有极低阈值电流４～６ｍＡ。２０～４０℃时特征温度Ｔ０高达６７Ｋ，室温下外量子效率为０．３ｍＷ／ｍＡ。     

F＋离子注入诱导应变层InGaAsP／InGaAs多量子阱结构无序的光荧光

本文研究了F~+离子注入诱导InGaAsP/InGaAs多量子阱结构,并着重研究了晶格匹配和失配应力对F~+离子注入诱导无序的影响,用变温光荧光(13～300K)方法研究了和带隙直接有关的光荧光峰值随温度变化的规律。在13K条件下,F~-离子注入具有压应力应变层的样品导致光荧光峰产生35meV的蓝移,而对具有张应力的样品,仅产生8meV的蓝移。定性地分析了产生不同程度蓝移的原因。     

Transform-limited 7-ps optical pulse generation using asinusoidally driven InGaAsP/InGaAsP strained multiple-quantum-well DFBlaser/modulator monolithically integrated light source

A 20-GHz optical pulse train is generated using a sinusoidally driven InGaAsP/InGaAsP strained multiple-quantum-well (MQW) DFB laser/intensity modulator monolithically integrated light source operating at low voltages (from -4- to -5-V DC bias with a 3.2- and 4.0-V peak-to-peak RF signal). An approximately-transform-limited 7-ps-wide optical pulse, with a spectral width of 47 GHz, is obtained     

High-performance λ=1.3 μm InGaAsP-InP strained-layerquantum well lasers

Compressively and tensile strained InGaAsP-InP MQW Fabry-Perot and distributed feedback lasers emitting at 1.3-μm wavelength are reported. For both signs of the strain, improved device performance over bulk InGaAsP and lattice-matched InGaAsP-InP MQW lasers was observed. Tensile strained MQW lasers show TM polarized emission, and with one facet high reflectivity (HR) coated the threshold currents are 6.4 and 12 mA at 20 and 60°C, respectively. At 100°C, over 20-mW output power is obtained from 250-μm-cavity length lasers, and HR-coated lasers show minimum thresholds as low as 6.8 mA. Compressively strained InGaAsP-InP MQW lasers show improved differential efficiencies, CW threshold currents as low as 1.3 and 2.5 mA for HR-coated single- and multiple quantum well active layers, respectively, and record CW output powers as high as 380 mW for HR-AR coated devices. For both signs of the strain, strain-compensation applied by oppositely strained barrier and separate confinement layers, results in higher intensity, narrower-linewidth photoluminescence emissions, and reduced threshold currents. Furthermore, the strain compensation is shown to be effective for improving the reliability of strained MQW structures with the quantum wells grown near the critical thickness. Linewidth enhancement factors as low as 2 at the lasing wavelength were measured for both types of strain. Distributed feedback lasers employing either compressively or tensile strained InGaAsP-InP MQW active layers both emit single-mode output powers of over 80 mW and show narrow linewidths of 500 kHz     

Frequency-domain measurement of carrier escape times in MQW electro-absorption optical modulators

Frequency-domain measurement of carrier escape times in reverse-biased multiple-quantum wells (MQW's) is proposed and demonstrated. Measurement and analysis of opto-to-electrical (OE) frequency response give the escape times of both electrons and holes with excellent time resolution. Using this technique, we measured escape times in an InGaAs-InAlAs MQW electro-absorption modulator and estimated the carrier density in the wells during optical input. This measurement can clarify the optical saturation effect in optical devices such as MQW electro-absorption modulators.     

Calculating the optical properties of multidimensionalheterostructures: Application to the modeling of quaternary quantum welllasers

A method for calculating the electronic states and optical properties of multidimensional semiconductor quantum structures is described. The method is applicable to heterostructures with confinement in any number of dimensions: e.g. bulk, quantum wells, quantum wires and quantum dots. It is applied here to model bulk and multiquantum well (MQW) InGaAsP active layer quaternary lasers. The band parameters of the quaternary system required for the modeling are interpolated from the available literature. We compare bulk versus MQW performance, the effects of compressive and tensile strain, room temperature versus high temperature operation and 1.3 versus 1.55 pm wavelength operation. Our model shows that: compressive strain improves MQW laser performance. MQW lasers have higher amplification per carrier and higher differential gain than bulk lasers, however, MQW performance is far from ideal because of occupation of non-lasing minibands. This results in higher carrier densities at threshold than in bulk lasers, and may nullify the advantage of MQW lasers over bulk devices for high temperature operation     

Monolithic integration of a quantum-well laser and an opticalamplifier using an asymmetric twin-waveguide structure

We demonstrate the monolithic integration of a 1.55 μm wavelength InGaAsP-InP multiple-quantum-well (MQW) laser and a traveling-wave optical amplifier using an asymmetric, vertical twin-waveguide structure. The laser and amplifier share the same strained InGaAsP MQW active layer grown by gas-source molecular beam epitaxy, while the underlying passive waveguide layer is used for on-chip optical interconnections between the active devices. The asymmetric twin-waveguide structure uses the difference in modal gains to discriminate between the even and odd modes     

Strain-compensated MQW electroabsorption modulator for increasedoptical power handling

InGaAsP MQW electroabsorption modulators with compressive strain in the wells and tensile strain in the barriers provide easier escape of photogenerated holes and operate at higher intensities before suffering saturation. Hole escape from wells is enhanced by a reduced energy difference between heavy-hole states in the well and light-hole states in the barrier     

Circular beam emission from 1.3 μm InGaAsPstrained-multiquantum-well lasers

The beam divergence in the vertical direction from a graded index separate confinement heterostructure (GRINSCH) multiquantum-well (MQW) laser has been studied. It is demonstrated both theoretically and experimentally that a circular beam MQW laser can be produced by choosing appropriate thicknesses for the GRINSCH layers, while maintaining other desired laser characteristics. The beam divergence is found to be more affected by the index change induced by injected carriers than by strain in the MQW active layer. Theoretical results are in good agreement with the measurements for 1.3-μm InGaAsP strained MQW lasers     

Tensile-strained multiple quantum-well structures for a largerefractive index change caused by current injection

Tensile-strained multiple quantum-well (MQW) structures with camel-back shaped first valence sub-bands are proposed as structures with a large refractive index change caused by current injection. These structures have a high joint density of states at the absorption edge, and the injected carriers in the structures have a long lifetime because of separation in the k-space between electrons and holes. The refractive index change caused by current injection is calculated for camel-back InGaAs/InGaAsP strained MQW structures for 1.55 μm-wavelength light. These structures show a larger refractive index change than the other InGaAs/InGaAsP strained/unstrained MQW structures     

The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-/spl mu/m multiple quantum-well structures

In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-/spl mu/m InGaAsP/InGaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from /spl lambda//sub g/= 1440 to 1260 nm) having different conduction band /spl Delta/E/sub c/ and valence band discontinuity /spl Delta/E/sub v/, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity /spl Delta/E/sub v/. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications.     

Compressively strained 1.3 μm InAsP/InP and GaInAsP/InP multiplequantum well lasers for high-speed parallel data transmission systems

Turn-on delay times in the pulse response of compressively strained InAsP/InP double-quantum-well (DOW) lasers and GaInAsP/InP multiple-quantum-well (MQW) lasers emitting at 1.3 μm were investigated. DQW lasers with 200-μm cavity length and high-reflection coating achieved both a very low threshold current (1.8 mA) and a small turn-on delay time (200 ps), even under a biasless 30-mA pulse current. Compressively strained or lattice-matched GaInAsP MQW lasers and GaInAsP double-heterostructure (DH) lasers were also fabricated and compared. It was observed that the carrier lifetime was enhanced for InAsP DQW lasers and strained GaInAsP MQW lasers compared to the lattice-matched GaInAsP MQW lasers and conventional double-heterostructure lasers. To explain this increase in the carrier lifetime, the effect of the carrier transport on the carrier lifetime was studied. The additional power penalty due to the laser turn-on delay was simulated and is discussed     

AlGaInP-GaInP compressively strained multiquantum-welllight-emitting diodes for polymer fiber application

We have studied the optical properties of the AlGaInP-GaInP light-emitting diodes (LED's), with a compressively strained multiquantum-well (CSMQW) active layer, emitting at 650 nm. It was found that by introducing a compressive strain into the MQW active layer, we can achieve a much faster operation speed and a higher output power. It was also found that a +0.33%, compressive strain can reduce the 10%-90% rise time and/or fall time from 50 to 15 ns. Furthermore, the +0.33% compressive strain can also increase the output power of the MQW AlGaInP-GaInP LED by more than 40%. Such a high operation speed and high output power LED is potentially useful in polymer-based optical fiber communication     

Optical-confinement-factor dependencies of the K factor, differential gain, and nonlinear gain coefficient for 1.55 mu m InGaAs/InGaAsP MQW and strained-MQW lasers

Optical-confinement-factor Gamma dependencies of the K factor, differential gain, dg/dN, and nonlinear gain coefficient epsilon , for 1.55 mu m InGaAs/InGaAsP multiple-quantum-well (MQW) and compressively strained MQW lasers, were investigated experimentally. For both MQW and strained-MQW lasers, when Gamma is increased, the K factor is reduced, dg/dN is increased, but epsilon is almost constant. These results indicate that the Gamma dependence of the K factor mainly results from a change in dg/dN, and does not result from a change in epsilon . For the strained MQW lasers, the K factor, dg/dN, and epsilon are, respectively, half as large, twice as large, and the same as those for the MQW lasers, when both types of lasers have the same Gamma (=0.05). This suggests that the strained MQW lasers with a large Gamma have a small K factor and thus are preferable for achieving large modulation bandwidths.<>     

Differential gain and linewidth enhancement factor of 1.5- mu m multiple-quantum-well active layers with and without biaxially compressive strain

The differential gain and the linewidth enhancement factor of 1.5- mu m multiple-quantum-well (MQW) active layers were measured with and without biaxially compressive strain as functions of the wavelength and the carrier density. These parameters of the strained MQW layer reveal stronger carrier-density dependence than those of the unstrained MQW layer. Most significantly, an anomalous increase in the linewidth enhancement factor is observed at high carrier densities. These characteristics are explained by a simple theoretical analysis.<>