GaAs-based 1.53 μm GaInNAsSb vertical cavity surface emitting lasers

Electrically-pumped GaAs-based 1.53 mum vertical cavity surface emitting lasers operating in pulsed mode at room temperature and continuous wave (CW) up to 20degC are reported for the first time. The lasers employ a GaInNAsSb/GaNAs multiple quantum well active region, a selectively oxidised AlAs aperture and p- and n-doped Al(Ga)As/GaAs distributed Bragg reflectors. Typical devices have room-temperature pulsed threshold current densities of 8.3 kA/cm and threshold voltages of 5.5 V. CW threshold currents as low as 2.87 mA for a 7 mum aperture device were observed at 15degC.     

Low-threshold continuous-wave 1.5-/spl mu/m GaInNAsSb lasers grown on GaAs

We present the first continuous-wave (CW) edge-emitting lasers at 1.5 /spl mu/m grown on GaAs by molecular beam epitaxy (MBE). These single quantum well (QW) devices show dramatic improvement in all areas of device performance as compared to previous reports. CW output powers as high as 140 mW (both facets) were obtained from 20 /spl mu/m /spl times/ 2450 /spl mu/m ridge-waveguide lasers possessing a threshold current density of 1.06 kA/cm/sup 2/, external quantum efficiency of 31%, and characteristic temperature T/sub 0/ of 139 K from 10/spl deg/C-60/spl deg/C. The lasing wavelength shifted 0.58 nm/K, resulting in CW laser action at 1.52 /spl mu/m at 70/spl deg/C. This is the first report of CW GaAs-based laser operation beyond 1.5 /spl mu/m. Evidence of Auger recombination and intervalence band absorption was found over the range of operation and prevented CW operation above 70/spl deg/C. Maximum CW output power was limited by insufficient thermal heatsinking; however, devices with a highly reflective (HR) coating applied to one facet produced 707 mW of pulsed output power limited by the laser driver. Similar CW output powers are expected with more sophisticated packaging and further optimization of the gain region. It is expected that such lasers will find application in next-generation optical networks as pump lasers for Raman amplifiers or doped fiber amplifiers, and could displace InP-based lasers for applications from 1.2 to 1.6 /spl mu/m.     

Performance improvement of 1.52 /spl mu/m (Ga,In)(N,As)/GaAs quantum well lasers on GaAs substrates

(Ga,In)(N,As)/GaAs single quantum well lasers have been grown by molecular beam epitaxy. Room temperature pulsed operation at a wavelength of 1515 nm is achieved. As-cleaved 1000 /spl mu/m-long lasers have a threshold current density of 4.06 kA/cm/sup 2/ and a slope efficiency of 0.075 W/A per facet.     

Continuous-wave operation of GaInAs-AlGaAsSb quantum cascade lasers

We report on the demonstration of continuous-wave (CW) operation of GaInAs-AlGaAsSb quantum cascade (QC) lasers. By placing a 2.5-/spl mu/m-thick gold layer on both sides of the laser ridge to extract heat from the active region in the lateral direction, together with mounting the device epilayer down, we have achieved CW operation of GaInAs-AlGaAsSb QC lasers composed of 25 stages of active/injection regions. The maximum CW operating temperature of the lasers is 94 K, and the emission wavelength is around /spl lambda//spl sim/4.65 /spl mu/m. For a device with the size of 10/spl times/2000 /spl mu/m/sup 2/, the CW optical output power per facet is 13 mW at 42 K and 4 mW at 94 K. The CW threshold current density is 1.99 kA/cm/sup 2/ at 42 K, and 2.08 kA/cm/sup 2/ at 94 K, respectively.     

High-performance 1.06-/spl mu/m selectively oxidized vertical-cavity surface-emitting lasers with InGaAs-GaAsP strain-compensated quantum wells

We present the first room-temperature continuous-wave operation of high-performance 1.06-/spl mu/m selectively oxidized vertical-cavity surface-emitting lasers (VCSEL's). The lasers contain strain-compensated InGaAs-GaAsP quantum wells (QW's) in the active region grown by metalorganic vapor phase epitaxy. The threshold current is 190 /spl mu/A for a 2.5/spl times/2.5 /spl mu/m/sup 2/ device, and the threshold voltage is as low as 1.255 V for a 6/spl times/6 /spl mu/m/sup 2/ device. Lasing at a wavelength as long as 1.1 /spl mu/m was also achieved. We discuss the wavelength limit for lasers using the strain-compensated QW's on GaAs substrates.     

High efficiency InGaAs/GaAs single-quantum-well lasers usingsingle-step metalorganic chemical vapor deposition

Low-threshold-current single-quantum-well InGaAs/GaAs lasers are fabricated by metalorganic chemical vapor deposition on a nonplanar substrate. By taking advantage of the growth rate and doping differences on different crystal facets during the growth, a buried heterostructure laser with natural current blocking p-n-p-n junction is formed by a single growth step. Threshold currents as low as 1.0 mA under pulsed operation and 1.2 mA under continuous-wave operation are obtained for uncoated lasers at room-temperature. The lasers showed high external quantum efficiency (80%) and high T₀ (150 K). High reflection coated laser (95%/95%) have CW threshold current as low as 0.28 mA     

Wide operating wavelength range and low threshold currentIn0.24Ga0.76As/GaAs vertical-cavitysurface-emitting lasers

Very low threshold current density operation of triple quantum well vertical-cavity surface-emitting lasers (VCSELs) is reported. The active wells are strained In_0.24Ga_0.76As in GaAs. Devices from the same wafer operate at room temperature over a wavelength range of 958-1042 nm, with a minimum threshold current density of 366 A-cm^-2 at 1018 nm. The dependence of threshold current on wavelength gives an insight into the optical gain spectrum of the quantum wells. It was shown that 50-μm-diameter devices operate CW without heatsinking     

Anomalous temporal response of gain guided surface emitting lasers

Under pulsed operation, gain guided surface emitting lasers have exhibited long delay times and higher threshold current than for CW operation. This phenomenon is explained by assuming that adiabatic heating of the active region results in time evolution of the transverse mode guiding. The authors' theory suggests that a built in index guiding greater than 10/sup -2/ will stabilise the fundamental mode and improve the temporal performance of surface emitting lasers.<>     

Room temperature continuous-wave operation of buried ridge stripe lasers using InAs-InP (100) quantum dots as active core

Self-organized InAs quantum-dot (QD) lasers emitting at 1.5 /spl mu/m were grown by gas source molecular beam epitaxy on (100) InP substrates. Room temperature continuous-wave (CW) operation of QD-based buried ridge stripe lasers is reported. We investigated experimentally the relevant CW performances of as-cleaved InP-based QD lasers for telecom applications such as temperature properties (T/sub 0/=56 K), infinite length threshold current density (J/sub /spl infin///spl sim/150 A/cm/sup 2/ per QDs layer) and internal efficiency (0.37 W/A). Lasing in pulsed mode is observed for cavity length as short as 200 /spl mu/m with a threshold current of about 37 mA, demonstrating the high gain of the QD's active core. In addition, the Henry parameter of these InP-based QD lasers is experimentally determined using the Hakki-Paoli method (/spl alpha//sub H//spl sim/2.2).     

Very-low-threshold 2.4-/spl mu/m GaInAsSb-AlGaAsSb laser diodes operating at room temperature in the continuous-wave regime

A GaInAsSb-AlGaAsSb large optical cavity triple-quantum-well structure was grown by molecular-beam epitaxy. Shallow mesa ridge-waveguide lasers with stripe width of 100 /spl mu/m were fabricated and tested. An internal losses coefficient as low as 4 cm/sup -1/ and a high internal quantum efficiency of 70% were obtained. In the pulsed regime at room temperature, the extrapolated threshold current densities for infinite cavity length is 78 A/cm/sup 2/. The threshold current density per quantum well is as low as 34 A/cm/sup 2/ for a 3-mm-long cavity.     

Room-temperature continuous-wave 1.55 /spl mu/m GaInNAsSb laser on GaAs

The first low-threshold 1.55 /spl mu/m lasers grown on GaAs are reported. Lasing at 1.55 /spl mu/m was observed from a 20/spl times/2400 /spl mu/m as-cleaved device with a room-temperature continuous-wave threshold current density of 579 A/cm/sup 2/, external efficiency of 41%, and 130 mW peak output power. The pulsed threshold current density was 550 A/cm/sup 2/ with >600 mW peak output power.     

Contribution of Auger recombination to saturation of the light-current characteristics in high-power laser diodes (λ = 1.0–1.9 m m)

Spectral and light-current characteristics of lasers based on the asymmetric separate-confinement heterostructures InGaAs/InGaAsAl/InP and InGaAs/GaAs/AlGaAs/GaAs were studied in the pulsed mode of lasing. It is shown that, at high levels of current pumping, the charge-carrier concentration in the active region of semiconductor lasers for the near-infrared optical region increases beyond the oscillation threshold; drastic saturation of the light-current characteristics is observed. Processes occurring in lasers as the charge-carrier concentration increases beyond the lasing threshold are studied theoretically. It is established that, at high pump levels, the rate of stimulated recombination decreases, the lifetime of charge carriers increases, and both the concentration of emitted photons and the quantum yield of stimulated radiation decrease. It is shown that variations in stimulated recombination, the decrease in the quantum efficiency, and saturation of the light-current characteristic in semiconductor lasers at high levels of current pumping are caused by the contribution of the nonradiative Auger recombination.     

Room-temperature continuous-wave quantum cascade lasers grown by MOCVD without lateral regrowth

We report on room-temperature continuous-wave (CW) operation of /spl lambda//spl sim/8.2 /spl mu/m quantum cascade lasers grown by metal-organic chemical vapor deposition without lateral regrowth. The lasers have been processed as double-channel ridge waveguides with thick electroplated gold. CW output power of 5.3 mW is measured at 300 K with a threshold current density of 2.63 kA/cm/sup 2/. The measured gain at room temperature is close to the theoretical design, which enables the lasers to overcome the relatively high waveguide loss.     

1.3 /spl mu/m GaAs/GaAsSb quantum well laser grown by solid source molecular beam epitaxy

A highly strained GaAs/GaAs/sub 0.64/Sb/sub 0.36/ single quantum well laser has been grown on GaAs (100) substrate by using solid source molecular beam epitaxy. The uncoated broad-area laser demonstrates 1.292 /spl mu/m pulsed operation with a low threshold current density of 300 A/cm/sup 2/. The spontaneous emission of the laser was also studied. The result reveals that the Auger recombination component dominates the threshold current at high temperature.     

Pulsed and CW high temperature operation of InGaAs/GaAs strained layer vertical cavity surface emitting lasers

The performance of strained layer InGaAs/GaAs vertical cavity surface emitting lasers defined by ion implantation over a approximately 75 degrees C temperature range is reported on. Maximum CW output levels for the temperature extremes of 10 and 86 degrees C are 7.5 MW and 200 mu W, respectively for 20*20 mu m/sup 2 /devices. The temperature dependence of the CW threshold current exhibits exponential behaviour to 80 degrees C.<>     

High temperature, high power InGaAs/GaAs quantum-well lasers withlattice-matched InGaP cladding layers

The authors report the high-temperature and high-power operation of strained-layer InGaAs/GaAs quantum well lasers with lattice-matched InGaP cladding layers grown by gas-source molecular beam epitaxy. Self-aligned ridge waveguide lasers of 3-μm width were fabricated. These lasers have low threshold currents (7 mA for 250-μm-long cavity and 12 mA for 500-μm-long cavity), high external quantum efficiencies (0.9 mW/mA), and high peak powers (160 mW for 3-μm-wide lasers and 285 mW for 5-μm-wide laser) at room temperature under continuous wave (CW) conditions. The CW operating temperature of 185°C is the highest ever reported for InGaAs/GaAs/InGaP quantum well lasers, and is comparable to the best result (200°C) reported for InGaAs/GaAs/AlGaAs lasers     

Continuous-wave operation of quantum cascade laser emitting near 5.6 /spl mu/m

Buried heterostructure quantum cascade lasers emitting at 5.64 /spl mu/m are presented. Continuous-wave (CW) operation has been achieved at -30/spl deg/C for junction down mounted devices with both facets coated. A 750 /spl mu/m-long laser exhibited 3 mW of CW power with a threshold current density of 5.4 kA/cm/sup 2/.     

具有线性GRIN结构GaAs/AlGaAs单量子阱激光器

采用ＭＯＣＶＤ 方法成功地研制了具有线性ＧＲＩＮ 结构ＧａＡｓ／ＡｌＧａＡｓ单量子阱激光器。该激光器的峰值波长为８１５～８２５ ｎｍ ,阈值电流为１３０ ｍ Ａ。工作电流在４８０ ｍ Ａ 时,单面连续输出光功率高达２００ ｍ Ｗ,且基本保持在单模工作状态。工作在９７０ ｍ Ａ 时,单面连续输出光功率为０．５ Ｗ。     

High-performance three-layer 1.3-/spl mu/m InAs-GaAs quantum-dot lasers with very low continuous-wave room-temperature threshold currents

The combination of high-growth-temperature GaAs spacer layers and high-reflectivity (HR)-coated facets has been utilized to obtain low threshold currents and threshold current densities for 1.3-/spl mu/m multilayer InAs-GaAs quantum-dot lasers. A very low continuous-wave (CW) room-temperature threshold current of 1.5 mA and a threshold current density of 18.8 A/cm/sup 2/ are achieved for a three-layer device with a 1-mm HR/HR cavity. For a 2-mm cavity, the CW threshold current density is as low as 17 A/cm/sup 2/ for an HR/HR device. An output power as high as 100 mW is obtained for a device with HR/cleaved facets.     

Submilliamp threshold current (0.62 mA at 0 degrees C) and high output power (220 mW) 1.5 mu m tensile strained InGaAs single quantum well lasers

The strain dependence of the threshold current density of lambda =1.5 mu m wavelength tensile strained In/sub x/Ga/sub 1-x/As (0.22<*<0.53)-InGaAsP single quantum well (SQW) lasers is reported. The optimum indium mole fraction was found to be 0.32 (1.5% strain), resulting in TM polarised lasers with threshold current densities as low as 92 A/cm/sup 2/. Using this SQW, buried heterostructure lasers with 0.62 mA threshold and 220 mW CW output power were realised.<>