Long wavelength GaInNAsSb/GaNAsSb multiple quantum well lasers

The high demand for 1.3-1.55 μm lasers has led to the investigation of GaInNAsSb/GaNAsSb on GaAs. In-plane lasers operating out to 1.49 μm, with threshold current density of 930 A/cm² per quantum well and pulsed power up to 70 mW, are presented. In addition, photoluminescence out to 1.6 μm from GaInNAsSb quantum wells was observed     

GaInNAsSb/GaAs vertical cavity surface emitting lasers at 1534 nm

Electrically pumped, C-band vertical cavity surface emitting lasers (VCSELs) grown on GaAs are reported for the first time. The VCSELs employed three GaInNAsSb quantum wells separated by GaNAs barriers. Pulsed lasing was observed at 1534 nm, in the ITU C-band, when cooled. These lasers exhibit the longest wavelength reported to date for electrically pumped VCSELs grown on GaAs substrates.     

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.     

λ=8.3 μm GaAs/AlAs quantum cascade lasers incorporatingInAs monolayers

The development of GaAs-based quantum cascade lasers incorporating indirect bandgap AlAs barriers in conjunction with ultrathin InAs layers in the active regions of the device is reported. The InAs layers produce a downshift of the energies of the lower lasing states, allowing laser emission to be observed at λ=8.34 μm. The GaAs/InAs/AlAs devices operate in pulsed mode up to a maximum temperature of 250 K, with a characteristic temperature of around 200 K for T>100 K     

Low-threshold 1.5 μm compressive-strained multiple- andsingle-quantum-well lasers

Design considerations for low-threshold 1.5-μm lasers using compressive-strained quantum wells are discussed. Parameters include transparency current density, maximum modal gain, bandgap wavelength, and carrier confinement. The optical confinement for a thin quantum well in the separate-confinement heterostructure (SCH) and the step graded-index separate-confinement heterostructure (GRINSCH) are analyzed and compared. 1.5-μm compressive-strained multiple- and single-quantum-well lasers have been fabricated and characterized. As a result of the compressive strain, the threshold current density is loss limited instead of transparency limited. By the use of the step graded-index separate-confinement heterostructure to reduce the waveguide loss, a low threshold current density of 319 A/cm² was measured on compressive-strained single-quantum-well broad-area lasers with a 27 μ oxide stripe width     

Multiple-quantum-well GaInNAs-GaNAs ridge-waveguide laser diodesoperating out to 1.4 μm

In this letter, results from a ridge waveguide laser diode (LD) structure, with three GaInNAs quantum wells (QWs) and GaNAs barriers, are presented. The sample was grown by solid source molecular beam epitaxy with an RF plasma nitrogen source. These devices differ from previously reported GaInNAs QWs LDs that used GaAs as the barrier material. The introduction of nitrogen into the barriers reduces the spectral blue shift caused by post-growth annealing. Long wavelength emission out to 1.405 μm was observed. The devices exhibited threshold current densities as low as 1.5 kA/cm², high differential efficiency of 0.67 W/A, and a maximum output power of 350 mW     

High-power GaInAsSb-AlGaAsSb multiple-quantum-well diode lasersemitting at 1.9 μm

High-power diode lasers emitting at ~1.9 μm have been fabricated from a quantum-well heterostructure having an active region consisting of five GaInAsSb wells and six AlGaAsSb barriers. For devices 300 μm wide and 1000 μm long, single-ended output power as high as 1.3 W cw has been obtained with an initial differential quantum efficiency of 47%. The pulsed threshold current density is as low as 143 A/cm² for 2000-μm-long devices     

High T0 long-wavelength InGaAsN quantum-well lasersgrown by GSMBE using a solid arsenic source

We demonstrate high performance, λ=1.3- and 1.4-μm wavelength InGaAsN-GaAs-InGaP quantum-well (QW) lasers grown lattice-matched to GaAs substrates by gas source molecular beam epitaxy (GSMBE) using a solid As source. Threshold current densities of 1.15 and 1.85 kA/cm² at λ=1.3 and 1.4 μm, respectively, were obtained for the lasers with a 7-μm ridge width and a 3-mm-long cavity. Internal quantum efficiencies of 82% and 52% were obtained for λ=1.3 and 1.4 μm emission, respectively, indicating that nonradiative processes are significantly reduced in the quantum well at λ=1.3 μm due to reduced N-H complex formation. These Fabry-Perot lasers also show high characteristic temperatures of T₀ =122 K and 100 K at λ=1.3 and 1.4 μm, respectively, as well as a low emission wavelength temperature dependence of (0.39±0.01) nm/°C over a temperature range of from 10°C to 60°C     

Strained-layer InGaAs-GaAs-InGaP buried-heterostructurequantum-well lasers on a low-composition InGaAs substrate byselective-area MOCVD

Aluminum-free buried-heterostructure quantum-well lasers have been successfully fabricated on low-composition InGaAs substrates. Selective-area metalorganic chemical vapor deposition (MOCVD) was utilized to investigate a variety of InGaAs quantum wells with a wide range of composition and thickness. Compressively strained quantum wells can be deposited thicker on substrates of InGaAs than GaAs before the generation of misfit dislocations. These deeper potential wells enable laser diodes with longer wavelengths (1.1504 μm) than GaAs-based emitters and higher characteristic temperatures (145 K) than InP-based devices     

Extremely large differential gain of 1.26 μm GaInNAsSb-SQW ridgelasers

The differential gain of long wavelength GaInNAs-based quantum film (QF) lasers and highly strained GaInAs-based QF lasers have been investigated for the first time. These lasers were grown by gas-source molecular beam epitaxy, and include a small amount of Sb to improve the crystalline quality. GaInNAsSb single quantum well (SQW) ridge lasers that oscillate at 1.258 μm have an extremely large differential gain of 1.06×10^-15 cm² in spite of the SQW lasers; therefore GaInNAsSb lasers are suitable for high-speed lasers in the long wavelength region     

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.     

Multiwavelength InGaAs/InGaAsP strained-layer MQW-laser array usingshadow-masked growth

A simple technique for fabricating multiwavelength laser arrays is presented. The lateral variations in bandgap (or emission wavelength) between the different lasers are obtained by the use of shadow-masked growth. The shadow masked growth results in variations in thickness (and to a lesser extent, in composition) over the substrate. In combination with a multiquantum well (MQW) active region, this gives the required bandgap variations. By varying the window width in the shadow mask between 10 μm and >500 μm it was possible to obtain a wavelength span of 130 nm centered around 1.55 μm. The strained-layer-ridge MQW Fabry-Perot lasers showed a constant threshold current (around 70 mA for an 11-μm×500-μm stripe)     

1.5-μm InGaAs/InAlGaAs quantum-well microdisk lasers

Microdisk lasers with three InGaAs/InAlGaAs quantum wells were demonstrated for the first time. The selective etching method used to fabricate the laser structure is discussed. Lasers 20 μm in diameter lased with single mode at 1.5-μm wavelength when optically pumped by a pulsed argon-ion laser at 80 K     

Data transmission over single-mode fiber by using 1.2-μmuncooled GaInAs-GaAs laser for Gb/s local area network

We demonstrate 2-Gb/s data transmission through a 5-km-long standard single-mode fiber by using a GaAs-based 1.2-μm GaInAs-GaAs quantum well laser. The fabricated laser exhibits a high characteristic temperature of 140 K. The results indicate the possibility of Gigabit/s local area networks (LANs) using uncooled lasers (possibly surface-emitting lasers) operating at a 1.2-μm wavelength band     

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 operation of VCSEL-pumped photonic crystal lasers

Room-temperature operation of two-dimensional photonic crystal lasers optically pumped by a vertical-cavity surface-emitting laser emitting at 860 nm is reported. The photonic crystal membrane is surrounded by air on both sides and consists of four compressively strained quantum wells as the active region. The incident threshold pump power of an approximately 2.6-μm-diameter hexagonal defect cavity laser operating at 1.6 μm is 2.4 mW     

A quantum leap in laser emission

Medium- and long-haul, high-speed fiber communication systems are dominated by the need for low optical loss and low dispersion, and these systems require laser diodes and photodiodes that emit and detect at 1.33 and 1.55 μm. InGaAs/GaAs quantum dots enable 1.3 μm wavelengths in GaAs-based lasers for fiber-optic communication     

Strain-compensated InGa(As)P-InAsP active regions for 1.3-μmwavelength lasers

The demonstration of an optimized strain compensated multiple-quantum-well (MQW) active region for use in 1.3-μm wavelength lasers is described. Utilizing narrow bandgap tensile-strained InGaAsP instead of wide bandgap InGaP barriers in strain-compensated lasers, we observe a reduction in threshold current density (Jth) from 675 to 310 A/cm² and in T₀ from 75 K to 65 K for 2-mm long seven quantum-well devices. Additionally, the lowest reported Jth for MBE grown 1.3-μm wavelength lasers of 120 A/cm² for single-quantum-well (SQW) 45-mm-long lasers was attained     

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     

Threshold analysis of highly detuned long-wavelength GaAs-based GaInNAsSb/GaNAsQWVCSELs

Comprehensive 3D optical–electrical–thermal-gain self-consistent simulation of physical processes taking place inside a laser volume of the GaAs-based GaInNAsSb/GaNAs quantum-well (QW) vertical-cavity surface-emitting diode laser (VCSEL) is carried out to examine a possibility to reach the long-wavelength room-temperature (RT) continuous-wave (CW) laser operation in highly detuned devices. The RT CW 1.422-μm lasing emission has been found to be reached practically without troubles. However, to reach the 1.5-μm laser wavelength, it is necessary to increase the QW active region temperature by about 100 K, which may be done by a proper increase in the RT CW operation current.