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     

High-temperature characteristic in 1.3-μm-range highly strainedGaInNAs ridge stripe lasers grown by metal-organic chemical vapordeposition

1.3-μm-range highly strained GaInNAs-GaAs double quantum-well ridge stripe lasers with different In contents (37% and 39%) grown by metal-organic chemical vapor deposition are demonstrated. The GaInNAs laser with In content of 37% emitting at 1.294 μm exhibited both a low threshold current density of 1.0 kA/cm² at 20°C and a high characteristic temperature of 148 K in the temperature range of 20°C-80°C     

Efficient continuous-wave lasing operation of a narrow-stripeoxide-confined GaInNAs-GaAs multiquantum-well laser grown by MOCVD

Efficient continuous-wave lasing operation has been achieved above room temperature by a triple-quantum-well GaInNAs-GaAs laser diode grown on a 6°-misoriented GaAs substrate by MOCVD. Using a planar, oxide-confined, narrow-stripe (8 μm) laser geometry, continuous-wave lasing operation was achieved over a wide range of temperatures up to 57°C. At room temperature, lasing occurs at a wavelength of 1.16 μm, with a high single-facet slope efficiency of 25% and a threshold current density of 1.3 kA/cm²     

Low-threshold operation of 1.3-μm GaAsSb quantum-well lasersdirectly grown on GaAs substrates

GaAsSb quantum-well (QW) edge-emitting lasers grown on GaAs substrates were demonstrated. The optical quality of the QW was improved by optimizing the growth conditions and introducing a multi-QW to increase the gain. As a result, 1.27-μm lasing of a GaAs_0.66 Sb_0.34-GaAs double-QW laser was obtained with a low-threshold current density of 440 A/cm², which is comparable to that in conventional InP-based long-wavelength lasers. 1.30 μm lasing with a threshold current density of 770 A/cm² was also obtained by increasing the antimony content to 0.36. GaAsSb QW was found to be a suitable material for use in the active layer of a 1.3-μm vertical-cavity surface-emitting lasers     

GaInNAs-GaAs long-wavelength vertical-cavity surface-emitting laserdiodes

Vertical-cavity surface-emitting laser diodes with GaInNAs-GaAs quantum-well (QW) active layers are demonstrated for the first time. GaInNAs permits the realization of a long-wavelength vertical-cavity laser grown directly on a GaAs substrate. Room-temperature (RT) pulsed operation is achieved, with an active wavelength near 1.18 μm, threshold current density of 3.1 kA/cm², slope efficiency of ~0.04 W/A, and output power above 5 mW for 45-μm-diameter devices. Laser oscillation is observed for temperatures at high as 95°C     

Room-temperature operation of InAs quantum-dash lasers on InP (001)

The first self-assembled InAs quantum dash lasers grown by molecular beam epitaxy on InP (001) substrates are reported. Pulsed room-temperature operation demonstrates wavelengths from 1.60 to 1.66 μm for one-, three-, and five-stack designs, a threshold current density as low as 410 A/cm² for single-stack uncoated lasers, and a distinctly quantum-wire-like dependence of the threshold current on the laser cavity orientation. The maximal modal gains for lasing in the ground-state with the cavity perpendicular to the dash direction are determined to be 15 cm^-1 for single-stack and 22 cm^-1 for five-stack lasers     

Long-wavelength strained quantum-well lasers oscillating up to210°C on InGaAs ternary substrates

Long-wavelength InGaAs-InAlGaAs strained quantum-well lasers have been fabricated on In_0.22Ga_0.78As ternary substrates grown by the Bridgman method. The threshold current density and lasing wavelength at 20°C are 245 A/cm² and 1.226 μm, respectively. The device has lased up to 210°C, which is the highest operating temperature ever reported for long-wavelength semiconductor lasers. The temperature sensitivity of the slope efficiency between 20°C and 120°C is only -0.0051 dB/K, showing suppressed carrier overflow owing to deep potential quantum wells. These high-temperature durabilities of this laser are fascinating features for application to optical subscriber and optical interconnection systems     

Low-threshold GaInNAs single-quantum-well lasers with emission wavelength over 1.3 /spl mu/m

Low-threshold GaInNAs single-quantum-well (SQW) lasers with emission wavelength over 1.3 mum are demonstrated. Epitaxial layers of the lasers are grown using an aluminium-free gas-source molecular-beam epitaxy (GS-MBE) to prevent any impurity or contamination related to aluminium that might be incorporated into the GaInNAs active layer. The fabricated laser is believed it exhibit the lowest threshold-current density (200 A/cm²) among GaInNAs-SQW lasers grown by MBE. Moreover, record low threshold current (5.2 mA) and long-wavelength (1.31 mum) emission were achieved in a ridge-waveguide laser at 25degC under continuous-wave operation     

Low-threshold current, high-efficiency 1.3-μm wavelengthaluminum-free InGaAsN-based quantum-well lasers

We demonstrate high-performance Al-free InGaAsN-GaAs-InGaP-based long-wavelength quantum-well (QW) lasers grown on GaAs substrates by gas-source molecular beam epitaxy using a RF plasma nitrogen source. Continuous wave (CW) operation of InGaAsN-GaAs QW lasers is demonstrated at λ=1.3 μm at a threshold current density of only J_TH =1.32 kA/cm². These narrow ridge (W=8.5 μm) lasers also exhibit an internal loss of only 3.1 cm^-1 and an internal efficiency of 60%. Also, a characteristic temperature of T₀=150 K from 10°C to 60°C was measured, representing a significant improvement over conventional λ=1.3 μm InGaAsP-InP lasers. Under pulsed operation, a record high maximum operating temperature of 125°C and output powers greater than 300 mW (pulsed) and 120 mW (CW) were also achieved     

Low-threshold continuous-wave two-stack quantum-dot laser withreduced temperature sensitivity

Data are presented on continuous wave operation of two-stack quantum dot lasers designed with reduced temperature sensitivity in their threshold. The InAs quantum dots are designed to have a wide energy spacing (~102 meV) between the ground and first excited radiative transitions. Selectively oxidized stripe lasers have continuous wave threshold currents as low as 1.2 mA for 2 μm wide stripes and minimum threshold current densities of 26 A/cm² for 13-μ-m wide stripes. Broad area lasers have continuous wave threshold current densities as low as 40 A/cm², even for p-up mounting. Ground state lasing is obtained up to the highest temperature measured of 326 K     

Characteristics of GaAsSb single-quantum-well-lasers emitting near1.3 μm

We report data on GaAsSb single-quantum-well lasers grown on GaAs substrates. Room temperature pulsed emission at 1.275 μm in a 1250-μm-long device has been observed. Minimum threshold current densities of 535 A/cm² were measured in 2000-μm-long lasers. We also measured internal losses of 2-5 cm^-1, internal quantum efficiencies of 30%-38% and characteristic temperatures T₀ of 67°C-77°C. From these parameters, a gain constant G₀ of 1660 cm^-1 and a transparency current density J_tr of 134 A/cm² were calculated. The results indicate the potential for fabricating 1.3-μm vertical-cavity surface-emitting lasers from these materials     

Low-threshold oxide-confined GaInNAs long wavelength verticalcavity lasers

We report, for the first time, room temperature continuous-wave (CW) operation of GaInNAs vertical-cavity surface-emitting laser diodes emitting at a wavelength of 1.2 μm and grown all-epitaxially in a single step on a GaAs substrate. Oxide-apertured devices demonstrated CW threshold currents as low as 1 mA, slope efficiency above 0.045 W/A, and thermal impedance of 1.24 K/mW. Larger sized devices exhibited a pulsed threshold current density of 2-2.5 kA/cm² and slope efficiency above 0.09 W/A     

Continuous-wave operation of long-wavelength quantum-dot diodelaser on a GaAs substrate

Continuous-wave operation near 1.3 μm or a diode laser based on self-organized quantum dots (QD's) on a GaAs substrate is demonstrated. Multiple stacking of InAs QD planes covered by thin InGaAs layers allows us to prevent gain saturation and achieve long-wavelength lasing with low threshold current density (90-105 A/cm²) and high output power (2.7 W) at 17°C heatsink temperature. It is thus confirmed that QD lasers of this kind are potential candidates to substitute InP-based lasers in optical fiber systems     

On-wafer continuous-wave operation of InGaN/GaN violet laser diodes

Continuous-wave operation of etched-facet InGaN/GaN multiquantum-well ridge-waveguide laser diodes grown by low pressure MOVPE on a sapphire substrate has been achieved on-wafer for >2 min at 15% above threshold. The threshold current density and voltage were 9.1 kA/cm² and 7.6 V, respectively, at 15°C, and the lasing wavelength was 400.6 nm     

High-performance long-wavelength (λ~1.3 μm) InGaAsPNquantum-well lasers

We demonstrate high-performance InGaAsPN quantum well based long-wavelength lasers grown on GaAs substrates, nitrogen containing lasers emitting in the λ=1.2- to 1.3-μm wavelength range were grown by gas source molecular beam epitaxy using a RF plasma nitrogen source. Under pulsed excitation, lasers emitting at λ=1.295 μm exhibited a record low threshold current density (J_TH) of 2. 5 kA/cm². Lasers grown with less nitrogen in the quantum well exhibited significantly lower threshold current densities of J_TH =1.9 kA/cm² at λ=1.27 μm and J_TH=1.27 kA/cm² at λ=1.2 μm. We also report a slope efficiency of 0.4 W/A and an output power of 450 mW under pulsed operation for nitrogen containing lasers emitting at 1.2 μm     

Room temperature continuous-wave operation of GaInNAs/GaAs VCSELsgrown by chemical beam epitaxy with output power exceeding 1 mW

The authors present a near 1200 nm wavelength vertical-cavity surface-emitting laser (VCSEL) the active region of which is formed by GaInNAs/GaAs quantum wells grown by chemical beam epitaxy. Room temperature continuous-wave operation has been demonstrated with a high slope efficiency of 0.23 W/A, a high output power of over 1.0 mW, and a singlemode output power of 0.34 mW. The fabricated devices with different aperture sizes show low threshold currents of 1.2-2.1 mA and a record low threshold current density of 2.6 kA/cm² in GaInNAs VCSELs     

Optimum design conditions for AlGaAs window stripe lasers

The maximum available CW optical power from the AlGaAs window stripe laser was investigated both theoretically and experimentally. It is found that a thin third AlGaAs layer thickness and high-quality pulsed lasing characteristics, such as low threshold current density and high external differential quantum efficiency, which are obtained from refractive index guiding and short window-region length, are necessary to increase CW optical power. Stable fundamental lateral transverse mode CW operation was achieved at 55 mW (∼4.7 MW/cm²) in a window stripe (WS) laser with 3 μm stripewidth, which is about five times higher than the typical catastrophic optical damage (COD) threshold in conventional structure lasers. It was also found that a high-quality window stripe laser with 3 μm stripewidth operated at 30 mW (∼2.6 MW/cm²) for more than 3500 h.     

Strained 1.3 μm MQW AlGaInAs lasers grown by digital alloy MBE

AlGaInAs strained MQW lasers, emitting at 1.3 μm, have been prepared for the first time using a digital alloy approach. 2 μm stripe geometry lasers have characteristics comparable to those of lasers prepared using bulk alloy layers. The infinite length threshold current densities are as low as 140 kA/cm²/quantum well and T ₀ values (20-40°C) range from 75-90 K for chip lengths of 375-2375 μm     

InGaAs quantum dot lasers with submilliamp thresholds and ultra-lowthreshold current density below room temperature

Continuous-wave operation of InGaAs quantum dot lasers is studied. A very low threshold current of 460 μA is achieved at 200 K for a 5 μm×1170 μm oxide-confined stripe laser. For a larger stripe width of 11 μm, a threshold current density of 5.2A/cm² is demonstrated. The characteristic threshold temperature is -700 K in the temperature range of 14-200 K, and drops rapidly around room temperature     

1.2-μm GaAsP/InGaAs strain compensated single-quantum-well diodelaser on GaAs using metal-organic chemical vapor deposition

We demonstrate here 1.2-μm laser emission from a GaAsP-InGaAs strain compensated single-quantum-well (SQW) diode. This development enables the fabrication of vertical-cavity surface-emitting lasers for optical interconnection through Si wafers. Strain compensation and low temperature growth were used to extend the wavelength of emission to the longest yet achieved on a GaAs substrate in this materials system. The minimum threshold density achieved was 273.4 A/cm² at a cavity length of 610 μm. We have also demonstrated an 1.144-μm lasing wavelength in a 820-μm-long cavity on a GaAs substrate with a strained InGaAs-GaAs SQW laser for comparison using a low-temperature metal-organic chemical vapor deposition growth technique. The threshold current density for a 590-μm-long cavity under CW operation was 149.7 A/cm²