CW operation and threshold characteristics of all-monolithic InAlGaAs 1.55-/spl mu/m VCSELs grown by MOCVD

We demonstrate an all-monolithic metal-organic chemical vapor epitaxy (MOCVD)-grown 1.55-/spl mu/m vertical-cavity surface-emitting laser operating continuous wave up to 35/spl deg/C. The structure is based on the InAlGaAs-InP material system grown by a single step of MOCVD. Wet oxidation of a strained In/sub 0.4/Al/sub 0.6/As layer is used for the current confinement. The threshold current, threshold voltage and the external quantum efficiency at room temperature are about 1.6 mA, 2.3 V, and 5.4%, respectively.     

Low threshold high-power room-temperature continuous-wave operation diode laser emitting at 2.26 /spl mu/m

Diode lasers emitting at 2.26 /spl mu/m, based on the InGaAsSb-AlGaAsSb materials system, are reported. These devices exhibit high internal quantum efficiency of 78% and low threshold current density of 184.5 A/cm/sup 2/ for a 2-mm-long cavity. Output power up to 700 mW (/spl ap/550 mW) has been obtained at 280 K (300 K) in continuous-wave operation with 100 /spl mu/m/spl times/1 mm lasers. These devices have been coated with an antireflection on the output facet and are mounted epilayer down on a copper block. The working temperature was maintained by a thermoelectric Peltier cooling element.     

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.     

Continuous-wave operation of all-epitaxial InP-based 1.3 /spl mu/m VCSELs with 57% differential quantum efficiency

All-epitaxial InP-based 1.3 /spl mu/m VCSELs with a record-high continuous-wave differential quantum efficiency (57%) for single active region long-wavelength devices are demonstrated. Low-loss optical mode confinement is achieved through a selectively etched undercut tunnel-junction aperture. Singlemode continuous-wave lasing was observed up to 87/spl deg/C and the room-temperature output power was 1.1 mW at a current of 4.1 mA and a wavelength of 1.305 /spl mu/m.     

1.42 /spl mu/m continuous-wave operation of GaInNAs laser diodes

Continuous-wave (CW) operation of GaInNAs laser diodes in the 1.4 /spl mu/m range has been realised for the first time. A GaInNAs double quantum well separate confinement heterostructure was grown by solid source molecular beam epitaxy. Threshold currents as low as 66 mA and external efficiencies as high as 0.29 W/A could be demonstrated in CW operation. Lasing was observed up to 150/spl deg/C and a characteristic temperature T/sub 0/ of 111K was demonstrated. The emission wavelength at room temperature was centred at 1417 nm.     

Efficient Modulation of InP-based 1.3-/spl mu/m VCSELs with AsSb-based DBRs

We demonstrate efficient error-free 3.125-Gb/s modulation of InP-based 1.3-/spl mu/m vertical-cavity surface-emitting lasers with AsSb-based distributed Bragg reflectors up to 60/spl deg/C. These devices demonstrated high differential efficiencies [>60% at room temperature (RT)], which resulted in a required bias current for modulation of only 5.9 mA. The measured extinction ratios were greater than 8 dB up to 60/spl deg/C with a peak-to-peak drive voltage of only 800 mV. The 3-dB-down RT small-signal bandwidth was 4.4 GHz at a bias of 5.9 mA.     

MOVPE-grown GaInNAs VCSELs at 1.3 /spl mu/m with conventional mirror design approach

1.3 /spl mu/m oxide confined GaInNAs VCSELs designed using the same design philosophy used for standard 850 nm VCSELs is presented. The VCSELs have doped mirrors, with graded and highly doped interfaces, and are fabricated using production-friendly procedures. Multimode VCSELs (11 /spl mu/m oxide aperture) with an emission wavelength of 1287 nm have a threshold current of 3 mA and produce 1 mW of output power at 20/spl deg/C. The maximum operating temperature is 95/spl deg/C. Emission at 1303 nm with 1 mW of output power and a threshold current of 7 mA has been observed from VCSELs with a larger detuning between the gain peak and the cavity resonance.     

Low threshold current 1.3-/spl mu/m GaInNAs VCSELs grown by MOVPE

The structure of the conventional contact 1.3-/spl mu/m GaInNAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) was optimized and low threshold current 1.3-/spl mu/m GaInNAs VCSELs grown by metal-organic vapor-phase epitaxy were reported. The idea is to optimize the active region, the doping profiles, and the pairs of p-distributed Bragg reflectors, and the detuning between the emission wavelength and the photoluminescence gain peak wavelength. The continuous-wave 1.0-mA threshold current was achieved for the single-mode VCSEL. For the multiple-mode VCSELs, the below 2-mA threshold currents at 5/spl deg/C-85/spl deg/C , the 1.13-mA threshold current at 55/spl deg/C, and 1.52-mA threshold current at 85/spl deg/C are the best results for 1.3-/spl mu/m GaInNAs VCSELs.     

Room-temperature continuous-wave laser operation of electrically-pumped 1.55 /spl mu/m VECSEL

A report is presented on room-temperature (RT) continuous-wave (CW) laser emission at 1.55 /spl mu/m of an all InP-based electrically-pumped vertical external-cavity surface-emitting laser (EP-VECSEL). Threshold currents of 1.4 kA/cm/sup 2/ and output powers of up to 0.3 mW were measured under CW operation at RT. A maximum output power of 2.7 mW has been obtained in quasi-CW operation at a heatsink temperature of 10.5/spl deg/C. This first result demonstrates that EP-VECSELs are a potential candidate for the realisation of compact vertical-cavity emitting sources.     

Room-temperature 2.81-/spl mu/m continuous-wave operation of GaInAsSb-AlGaAsSb laser

GaInAsSb-AlGaAsSb multiple quantum-well (QW) lasers with an emission wavelength of 2.81 /spl mu/m are reported. The ridge waveguide lasers with highly strained QWs show continuous-wave laser emission up to 25/spl deg/C; in pulsed mode, the lasers operate up to 60/spl deg/C. For pulsed operation, a threshold current density of 360 A/cm/sup 2/ is found for devices with 30-/spl mu/m stripe width and 2-mm cavity length at room temperature. A low threshold current density at infinite length of 248 A/cm/sup 2/ is derived.     

Room-temperature continuous-wave operation of GaInNAsSb laser diodes at 1.55 /spl mu/m

The first 1.55 /spl mu/m room-temperature continuous-wave (CW) operation of GaAs-based laser diodes utilising GaInNAsSb/GaNAs double quantum well active regions grown by molecular beam epitaxy is reported. In electrically-pumped CW operation the narrow ridge waveguide devices have a room temperature lasing wavelength of 1550 nm near threshold, increasing to 1553 nm at thermal rollover. The CW threshold current was 132 mA for a 3/spl times/589 /spl mu/m device, with a characteristic temperature of 83 K, measured in pulsed mode between 20 and 70/spl deg/C.     

90/spl deg/C continuous-wave operation of 1.83-/spl mu/m vertical-cavity surface-emitting lasers

Excellent lasing performance is demonstrated for a 1.83-/spl mu/m InGaAlAs-InP vertical-cavity surface-emitting laser (VCSEL) utilizing the buried tunnel junction technology. Threshold currents as low as 190 /spl mu/A at 20/spl deg/C and operating temperatures as high as 90/spl deg/C have been measured. These values are the best ones reported so far for long-wavelength VCSELs.     

2.5-mW single-mode operation of 1.55-/spl mu/m buried tunnel junction VCSELs

We present 1.55-/spl mu/m wavelength buried tunnel junction InGaAlAs-InP vertical-cavity surface-emitting lasers with low threshold current and high efficiency. An improved mirror design is accomplished with high-reflective low-loss epitaxial InGaAlAs-InAlAs and hybrid dielectric CaF/sub 2/-ZnS-Au layer stacks, respectively. Lasers with aperture diameters of only around 5 /spl mu/m exhibit continuous-wave single-mode output powers at room temperature well beyond 2 mW. Threshold voltages and series resistances as low as 0.9 V and 30-40 /spl Omega/ have been measured. The spectral behavior shows excellent performance over the relevant current and temperature range.     

InP-based all-epitaxial 1.3-/spl mu/m VCSELs with selectively etched AlInAs apertures and Sb-based DBRs

We report, for the first time, InP-based all-epitaxially grown 1.3-/spl mu/m vertical-cavity surface-emitting lasers with lattice-matched Sb-based distributed Bragg reflectors and AlInAs etched apertures. The minimum threshold current and voltage under pulsed operation were 3 mA and 2.0 V, respectively. The thermal impedance was as low as 1.2 K/mW without heat sinking. Implementation of the AlInAs etched aperture was quite effective in improving the injection efficiency and reducing the internal loss, resulting in improved differential efficiency.     

28 GHz optical injection-locked 1.55 /spl mu/m VCSELs

A record resonance frequency of 28 GHz and an intrinsic laser 3 dB bandwidth of 34 GHz is reported for a directly modulated injection-locked 1.55 /spl mu/m VCSEL. The small-signal modulation response is experimentally investigated using polarisation-maintaining components.     

Single-frequency tunable Sb-based VCSELs emitting at 2.3 /spl mu/m

We present a comparison between two kinds of single-frequency Sb-based semiconductor VCSELs operating at 2.3 /spl mu/m in continuous-wave regime at room temperature. These lasers are studied in view of application to spectroscopy or trace gas detection. Both are based on a molecular beam epitaxy grown half-VCSEL. In the first configuration, a dielectric mirror is deposited on top to form a microcavity, while in the second a concave mirror is used to form an external cavity. The external cavity VCSEL exhibits 5-mW output power, a narrow linewidth (<<20 kHz), and 50-GHz continuous frequency tunability.     

80/spl deg/C continuous-wave operation of 2.01-/spl mu/m wavelength InGaAlAs-InP vertical-cavity surface-emitting lasers

Electrically pumped buried tunnel junction InGaAlAs-InP vertical-cavity surface-emitting lasers (VCSELs) with self-adjusted lateral current and optical confinement and record emission wavelengths beyond 2 /spl mu/m are presented. Front and back side mirrors are realized using 31.5 epitaxial layer pairs of alternating InGaAs-InAlAs and a dielectric 2.5 pair CaF/sub 2/-a-Si layer stack. The devices show single-mode continuous-wave operation up to heat sink temperatures over 80/spl deg/C. The maximum output power at 20/spl deg/C reaches 0.43 mW, threshold current and voltage are as low as 0.66 mA and 0.73 V, respectively. To reach the long emission wavelength, we use an optimized active region comprising heavily strained quantum wells. High-resolution X-ray diffraction and photoluminescence measurements reveal excellent material quality without relaxation in the quantum wells.     

50-GHz optically injection-locked 1.55-/spl mu/m VCSELs

High-speed directly modulated diode lasers are important for optical communications and optical interconnects. In this work, we demonstrate greatly enhanced resonance frequency for vertical-cavity surface-emitting lasers, from 7 to 50 GHz, under ultrahigh injection-locking conditions. In addition, a 20-dB gain is achieved for small signal modulation below resonance frequency.     

1.3 /spl mu/m InAs/GaAs multilayer quantum-dot laser with extremely low room-temperature threshold current density

A high growth temperature step used for the GaAs spacer layer is shown to significantly improve the performance of 1.3 /spl mu/m multilayer InAs/GaAs quantum-dot lasers. Extremely low room-temperature continuous-wave threshold current densities of 32.5 and 17 A/cm/sup 2/ are achieved for a three-layer device with as-cleaved facets and high-reflectivity coated facets, respectively.