GaInP/AlGaInP index waveguide-type visible laser diodes with dry-etched mesa stripes

GaInP/AlGaInP index waveguide-type visible-light laser diodes with dry-etched mesa stripes have been fabricated by Cl/sub 2/ reactive ion beam etching for the first time. The AlGaInP cladding layer, which is normally very difficult to dry etch due to problems with Al oxidation and the low volatility of In and its reaction products, was etched smoothly with high depth accuracy. The etched mesa stripes were buried by metal organic vapour-phase epitaxy without crystal discontinuity at the regrown surface. The threshold current under room-temperature pulsed operation is 35 mA (L=300 mu m), which is almost the same value as that for wet-etched lasers.<>     

GaInAsP/InP surface emitting lasers grown by chemical beam epitaxy

A GaInAsP/InP surface emitting laser has been demonstrated grown by chemical beam epitaxy (CBE) for the first time. The device has a 30 mu m round-low mesa with a 1.0 mu m active layer. The threshold current as low as 2.7 mA (455 A/cm/sup 2/) was obtained under 77 K CW operation (=1.43 mu m). This is the lowest value of long wavelength SE lasers ever reported. These results show the possibility of realising high performance SE lasers grown by CBE.<>     

Room-temperature continuous-wave operation of InAs quantum-wire laser on InP(001) substrate

A self-assembled quantum-wire laser structure was grown by solid-source molecular beam epitaxy in an InAlGaAs-InAlAs matrix on InP(001) substrate. Ridge-waveguide lasers were fabricated and demonstrated to operate at a heatsink temperature up to 330 K in continuous-wave (CW) mode. The emission wavelength of the lasers with 5 mm-long cavity was 1.713 /spl mu/m at room temperature in CW mode. The temperature stability of the devices was analysed and the characteristic temperature was found to be 47 K in the range of 220-320 K.     

High performance 1.28 /spl mu/m GaInNAs double quantum well lasers

The use of multiple quantum wells and GaAs barriers favours the temperature stability and modulation bandwidth of GaInNAs lasers. It is shown that a very low threshold current density and a high characteristic temperature can be achieved for GaInNAs/GaAs double quantum well lasers, emitting at 1.28 /spl mu/m, when grown by molecular beam epitaxy under favourable conditions.     

Vertical-cavity surface-emitting lasers integrated onto siliconsubstrates by PdGe contacts

Vertical-cavity surface-emitting lasers (VCSELs) have been integrated onto an aluminium coated silicon substrate. The InGaAs top-emitting VCSELs were grown by molecular beam epitaxy and individual lasers were defined by high energy proton implantation. The substrate was removed by a new substrate removal process and the lasers were bonded to an aluminised silicon substrate using a Pd/Ge/InSn contact. Threshold currents below 5.5 mA and output powers of ~1 mW were obtained for 40 μm VCSELs bonded to Si     

High-power singlemode CW operation of 1.5 /spl mu/m-range quantum dot GaAs-based laser

Narrow ridge stripe lasers with metamorphic InAs/InGaAs quantum dots grown using molecular beam epitaxy on GaAs substrates emit in the 1.5 /spl mu/m wavelength range demonstrating a differential quantum efficiency of about 50%, singlemode operation, and maximum continuous-wave power of 220 mW limited by thermal roll-over. Absence of beam filamentation is demonstrated up to the highest power levels studied.     

High-T/sub 0/ strain-compensated InGaAsSb-AlGaAsSb quantum-well lasers emitting at 2.43 /spl mu/m

Strain-compensated InGaAsSb-AlGaAsSb quantum-well (QW) lasers emitting near 2.5 /spl mu/m have been grown by solid-source molecular beam epitaxy. The relatively high arsenic composition causing a tensile strain in the Al/sub 0.25/GaAs/sub 0.08/Sb barriers lowers the valence band edge and the hole energy level, leading to an increased hole confinement and improved laser performance. A 60% external differential efficiency in pulsed mode was achieved for 1000-/spl mu/m-long lasers emitting at 2.43 /spl mu/m. A characteristic temperature T/sub 0/ as high as 163 K and a lasing-wavelength temperature dependence of 1.02 nm//spl deg/C were obtained at room temperature. For 2000 /spl times/ 200 /spl mu/m/sup 2/ broad-area three-QW lasers without lateral current confinement, a low pulsed threshold of 275 A/cm/sup 2/ was measured.     

High-quality 1.3 /spl mu/m GaInNAs single quantum well lasers grown by MBE

High-quality 1.3 /spl mu/m GaInNAs/GaNAs single quantum well lasers grown by molecular beam epitaxy are reported. The broad area lasers show a record low threshold current density of 318 A/cm/sup 2/ for a cavity length of 1 mm, a transparent current density of 84 A/cm/sup 2/, and a characteristic temperature of 103 K from 8 to 70/spl deg/C.     

High-modal gain 1300-nm In(Ga)As-GaAs quantum-dot lasers

A semiconductor laser containing seven InAs-InGaAs stacked quantum-dot (QD) layers was grown by molecular beam epitaxy. Shallow mesa ridge-waveguide lasers with stripe width of 120 /spl mu/m were fabricated and tested. A high modal gain of 41 cm/sup -1/ was obtained at room temperature corresponding to a modal gain of /spl sim/6 cm/sup -1/ per QD layer, which is very promising to enable the realization of 1.3-/spl mu/m ultrashort cavity devices such as vertical-cavity surface-emitting lasers. Ground state laser action was achieved for a 360-/spl mu/m-cavity length with as-cleaved facets. The transparency current density per QD layer and internal quantum efficiency were 13 A/cm/sup 2/ and 67%, respectively.     

`Flip-chip' transfer of ZnSSe/ZnSe/CdZnSe LED films

A ZnSSe/ZnSe/CdZnSe light-emitting diode (LED) film grown on GaAs by molecular beam epitaxy (MBE) has been successfully transferred from a GaAs substrate to a silicon substrate by combining both mechanical polishing and chemical wet etching techniques. The external quantum efficiency of the LED was enhanced by more than a factor of 2 via insertion of a reflector layer beneath the device structure. The device can be implemented in hybrid quasimonolithic integration. Technology applications include fabrication of LEDs with enhanced external quantum efficiency and II-VI surface emitting lasers     

1.27 /spl mu/m metamorphic InGaAs quantum well lasers on GaAs substrates

Pulsed operation at a wavelength of 1.27 /spl mu/m from metamorphic ridge-waveguide (RWG) InGaAs quantum well lasers on GaAs substrates using an alloy graded buffer, grown by molecular beam epitaxy, is demonstrated. Laser performance is anisotropic along the two orthogonal <1/spl plusmn/10> directions with lower threshold currents along the <1-10> direction. Post-growth rapid thermal annealing further reduces threshold currents. For 4 /spl mu/m-wide RWG lasers, minimum threshold current densities are 1-2.5 kA/cm/sup 2/ for cavity lengths 0.6-1.5 mm.     

Low threshold current density 1.3 /spl mu/m InAs/InGaAs quantum dot lasers with InGaP cladding layers grown by gas-source molecular-beam epitaxy

InAs/InGaAs quantum dot lasers with InGaP cladding layers grown by gas-source molecular-beam epitaxy (MBE) are reported. The laser emits 1.296 /spl mu/m light output and demonstrates a very low threshold current density of 111 A/cm/sup 2/. This is the lowest reported value of GaAs-based 1.3 /spl mu/m quantum dot lasers with InGaP cladding layers.     

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).     

Low-threshold 1.5 mu m DFB laser grown by GSMBE

GaInAsP 1.5 mu m DFB lasers with a low threshold current (17 mA) have been grown by gas source molecular beam epitaxy (GSMBE) in a two-step epitaxial process. The lasers exhibit single-mode emission for emitted power in excess of 10 mW with side mode suppression ratio of 40 dB and spectral linewidth of 15 MHz. In addition the dispersion of the lasing wavelength has been found to be as low as 1.7 nm.<>     

Room-temperature intersubband emission from GaInAs-AlAsSb quantum cascade structure

Room-temperature (300 K) intersubband electroluminescence has been obtained from a quantum cascade structure adopting triple-well vertical-transition active regions, based on Ga/sub 0.47/In/sub 0.53/As/AlAs/sub 0.56/Sb/sub 0.44/ heterostructures grown lattice-matched on InP substrate by molecular beam epitaxy. The emission peak wavelength varies from 4.3 /spl mu/m at 77 K to 4.5 /spl mu/m at 300 K.     

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.     

Broad-stripe near-diffraction-limited mid-infrared laser with a second-order photonic-crystal distributed feedback grating

Electron-beam lithography was used to pattern a second-order photonic-crystal distributed feedback grating onto an antimonide type-II "W" laser emitting at /spl lambda//spl ap/3.7 /spl mu/m. For pulsed optical pumping, the output beam was essentially diffraction-limited up to a stripe width of 150 /spl mu/m, and remained no worse than eight times the diffraction limit for stripes as wide as 600 /spl mu/m. This represents a considerable improvement over all previous mid-infrared semiconductor lasers with such broad stripes.     

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.     

1.5 /spl mu/m laser on GaAs with GaInNAsSb quinary quantum well

A 1.50 /spl mu/m broad area edge emitting laser is demonstrated with a structure grown by molecular beam epitaxy on a GaAs substrate. The active region is based on a single GaInNAsSb quantum well. The threshold current density is 3.5 kA/cm/sup 2/. Output power over 22 mW per facet is achieved.     

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.