Double heterostructure and multiquantum-well lasers at 1.5?1.7 ?m grown by atmospheric pressure MOVPE

The first successful growth and fabrication of GaInAs/InP MQW and CW GaInAsP DH lasers by atmospheric pressure MOVPE is reported. Room-temperature CW operation of DH lasers was obtained by using the ridge-waveguide laser design, and threshold currents as low as 53 mA were measured. MQW lasers, which also operated at room temperature, were fabricated, and emission spectra obtained from these devices showed a clear spectral narrowing compared with the DH lasers together with a wavelength shift, in good agreement with theoretical predictions.     

Very low-threshold (0.8 kA/cm2)InGaAsP/InP DH 1.5 ?m lasers grown by atmospheric MOVPE

Broad-area lasers have been fabricated from five separate atmospheric MOVPE DH wafers. Good agreement is found with expected theoretical predictions of the threshold/length and active-layer thickness dependences. The FWHM of the radiation in the plane perpendicular to the junction is well described by published values of active and cladding refractive indices.     

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     

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.     

Low threshold current density 1.5 mu m GaInAs/AlGaInAs graded-index separate-confinement-heterostructure quantum well laser diodes grown by metal organic chemical vapour deposition

A low threshold current density of 640 A/cm/sup 2/ was obtained in a 1.5 Gmm GaInAs/AlGaInAs multiple quantum well laser diode, grown by metal organic chemical vapour deposition, with continuously graded-index separate-confinement heterostructure. An internal waveguide loss of 14 cm/sup -1/ and internal quantum efficiency of 59% were obtained, which are comparable to those of GaInAs/GaInAsP quantum well laser diodes.<>     

High power operation of GaInAsP/GaInAs MQW ridge lasers emitting at 1.48 mu m

Multi-quantum-well (MQW) ridge lasers have been produced with CW light outputs in excess of 100 mW at 500 mA. The wavelength of operation is 1480 nm and the lasers are suitable for pumping erbium-doped-fibre amplifiers. These are the highest power ridge lasers yet produced in the 1500 nm wavelength region.<>     

1.55 mu m multiquantum-well lasers with record performance obtained by atmospheric pressure MOVPE using organometallic phosphorus precursor

The recently available precursor biphosphinoethane (BPE) was used, alongside with phosphine and with tertbutylphosphine (TBP), to grow advanced multiquantum-well (MQW) laser wafers with five quaternary, compressive strained wells. The lowest threshold current densities and the lowest optical losses were obtained with BPE. In particular, the lowest threshold current density, 328 A/cm/sup 2/, is a record among published values for lasers with five wells. In this comparison, the wafer grown with phosphine came a close second and that grown with TBP was third.<>     

Characterization of the temperature sensitivity of gain and recombination mechanisms in 1.3-/spl mu/m AlGaInAs MQW lasers

The potential of 1.3-/spl mu/m AlGaInAs multiple quantum-well (MQW) laser diodes for uncooled operation in high-speed optical communication systems is experimentally evaluated by characterizing the temperature dependence of key parameters such as the threshold current, transparency current density, optical gain and carrier lifetime. Detailed measurements performed in the 20/spl deg/C-100/spl deg/C temperature range indicate a localized T/sub 0/ value of 68 K at 98/spl deg/C for a device with a 2.8 /spl mu/m ridge width and 700-/spl mu/m cavity length. The transparency current density is measured for temperatures from 20/spl deg/C to 60/spl deg/C and found to increase at a rate of 7.7 A/spl middot/cm/sup -2//spl middot/ /spl deg/C/sup -1/. Optical gain characterizations show that the peak modal gain at threshold is independent of temperature, whereas the differential gain decreases linearly with temperature at a rate of 3/spl times/10/sup -4/ A/sup -1//spl middot//spl deg/C/sup -1/. The differential carrier lifetime is determined from electrical impedance measurements and found to decrease with temperature. From the measured carrier lifetime we derive the monomolecular ( A), radiative (B), and nonradiative Auger (C) recombination coefficients and determine their temperature dependence in the 20/spl deg/C-80/spl deg/C range. Our study shows that A is temperature independent, B decreases with temperature, and C exhibits a less pronounced increase with temperature. The experimental observations are discussed and compared with theoretical predictions and measurements performed on other material systems.     

High-performance 1.5 /spl mu/m GaInNAsSb lasers grown on GaAs

Substantially reduced threshold current density and improved efficiency in long-wavelength (>1.4 /spl mu/m) GaAs-based lasers are reported. A 20/spl times/1220 /spl mu/m as-cleaved device showed a room temperature continuous-wave threshold current density of 580 A/cm/sup 2/, external efficiency of 53%, and 200 mW peak output power at 1.5 /spl mu/m. The pulsed threshold current density was 450 A/cm/sup 2/ with 1145 mW peak output power.     

High performance DFB-MQW lasers at 1.5 mu m grown by GSMBE

1.5 mu m GaInAs multiquantum well distributed feedback lasers have been successfully fabricated on an InP grating substrate by GSMBE. DFB mode oscillation at high output power (50 mW) and narrow linewidth (1.3 MHz) have been obtained.<>     

Efficient CW lasing and high-speed Modulation of 1.3-/spl mu/m AlGaInAs VCSELs with good high temperature lasing performance

The 1.31-/spl mu/m AlGaInAs vertical-cavity surface-emitting lasers achieved efficient single-mode (SM) continuous-wave lasing at temperatures up to 120/spl deg/C, with 2.0-mW output power and 31% slope efficiency, as well as multimode (MM) lasing with up to 9-mW output power and up to 39% slope efficiency. High-speed modulation at data rates up to 10 Gb/s and transmission through different lengths of SM and MM fiber are demonstrated.     

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.     

Low-threshold operation of 1.34-/spl mu/m GaInNAs VCSEL grown by MOVPE

Low-threshold operation was demonstrated for a 1.34-/spl mu/m vertical-cavity surface-emitting laser (VCSEL) with GaInNAs quantum wells (QWs) grown by metal-organic vapor-phase epitaxy. Optimizing the growth conditions and QW structure of the GaInNAs active layers resulted in edge-emitting lasers that oscillated with low threshold current densities of 0.87 kA/cm/sup 2/ at 1.34 /spl mu/m and 1.1 kA/cm/sup 2/ at 1.38 /spl mu/m, respectively. The VCSEL had a low threshold current of 2.8 mA and a lasing wavelength of 1.342 /spl mu/m at room temperature and operated up to 60/spl deg/C.     

1.5< lambda <1.7 mu m strained multiquantum well InGaAs/InGaAsP diode lasers

The long wavelength limitations of strained In/sub 0.7/Ga/sub 0.3/As/InGaAsP four-quantum well (QW) lasers are investigated. For this confining structure and QW composition, wavelengths range from 1.52 to 1.72 mu m for QW thicknesses between 33 and 70 AA, and there is an optimum QW thickness of approximately 40 AA.<>     

Low-threshold operation of 1.5?m buried-heterostructure DFB lasers grown entirely by low-pressure MOVPE

Buried-heterostructure (BH) distributed feedback (DFB) lasers have been fabricated by a three-step low-pressure MOVPE process. The CW threshold currents were as low as 15mA and a high differential efficiency of 0.21 W/A was obtained. The laser operated in a stable single longitudinal mode over a wide range of driving currents and under highspeed direct modulation.     

1.5-/spl mu/m InGaAsP-InP slab-coupled optical waveguide lasers

We report the demonstration of high-power semiconductor slab-coupled optical waveguide lasers (SCOWLs) operating at a wavelength of 1.5 /spl mu/m. The lasers operate with large (4/spl times/8 /spl mu/m diameter) fundamental mode and produce output power in excess of 800 mW. These structures have very low loss (/spl sim/0.5 cm/sup -1/) enabling centimeter-long devices for efficient heat removal. The large fundamental mode allows 55% butt-coupling efficiency to standard optical fiber (SMF-28). Comparisons are made between SCOWL structures having nominal 4- and 5-/spl mu/m-thick waveguides.     

2.33 /spl mu/m-wavelength InAs/InGaAs multiple-quantum-well lasers grown by MOVPE

An emission wavelength of 2.33 mum in an InAs/InGaAs multiple-quantum-well laser grown by metal-organic vapour phase epitaxy is reported. The laser had an output power above 10 mW under continuous-wave operation at temperatures between 15 and 45degC. High-temperature operation up to 50degC and a characteristic temperature of 51 K were also confirmed.     

Low-threshold 1.3 ?m GaInAsP/InP lasers grown by atmospheric-pressure MOVPE

Room-temperature pulsed operation has been achieved at and below 1.3 ?m for GaInAsP/InP lasers grown by atmospheric-pressure metalorganic vapour phase epitaxy. Thresholds as low as 1.0 kA/cm2 (for a cavity length of 1000 ?m) have been obtained.     

Highly reliable planar GaInAs/InP photodiodes with high yield madeby atmospheric pressure MOVPE

A process for making GaInAs/InP PIN photodiodes based on atmospheric pressure MOVPE is described. The technique gives devices with very low dark currents (≪1 nA) and capacitances (<0.2 pF). Yields on large area wafers greater than 80% can be achieved and extremely good reliability has been demonstrated (<0.4 FIT at 20°C)     

The properties of MOVPE grown 1.3 μm DFB MQW lasers infilled with semi-insulating InP fabricated on semi-insulating substrates

The use of optoelectronic integrated circuits (OEICs) is now emerging as a practical technology for a variety of applications, particularly in advanced telecommunications. OEICs consist of a range of devices such as lasers, waveguides, modulators, amplifiers, transistors, detectors, etc. fabricated on the same substrate. When a semi-insulating substrate is used, these devices can be electrically isolated by channel etching, resulting in a low capacitance structure with reduced electrical interference between the subcomponents. One of the devices which is particularly advantageous for this type of integration scheme is the distributed feedback (DFB) laser. The laser can be made to function more efficiently by minimizing the current flowing outside the active region. This can be achieved by surrounding the active region with semi-insulating iron doped InP. This work describes for the first time, the MOVPE growth, fabrication, and device characterization of 1.3 um buried heterostructure DFB MQW lasers, which combine the advantages of using both a semi-insulating substrate and a semi-insulating infill region in the same device structure. The potential advantage of this design scheme is improved OEIC performance as a result of, reduced capacitance and electrical crosstalk, enhanced laser output power, higher speed, increased efficiency, wider operating temperature and reduced threshold current. The laser active region consists of 8 x 140 Å quantum wells of GalnAsP (λ = 1.3 μm) and 110 Åbarriers of GalnAsP (λ= 1.07 μm). Single mode 1.3 urn devices of length 250 μm operating at room temperature produced threshold currents of 8 mA, efficiencies of up to 25%, output powers of 18 mW at 80 mA (pulsed), and a frequency response greater than 12GHz. The parasitic capacitance was estimated to be less than 3 pF.