A new approach in the design of (Al)InGaAsSbGaSb quantum-well separate confinement heterostructure (QW-SCH) diode lasers has led to continuous-wave (CW) room-temperature lasing up to 2.7 m. This has been achieved by using quasiternary heavily strained InGaSb(As) QW's inside a broad-waveguide SCH laser structure. The QW compositions are chosen in the region outside the miscibility gap and, as a consequence, do not suffer from clustering and composition inhomogeneity normally found with quaternary InGaAsSb compounds of 2.3-2.7-m spectral range. Very low threshold current density (300 A/cm 2 ) and high CW output powers (>100 mW) were obtained from devices operating in the 2.3-2.6-m wavelength range.Index Terms-Broad-waveguide separate confinement quantum-well laser structure, continuous-wave operation, heavily strained quantum well, mid-infrared AlGaAsSb-InGaAsSb diode lasers.
Al-free 980 nm InGaAs/InGaAsP/InGaP laser structures grown by low-pressure metalorganic chemical vapor deposition ͑LP-MOCVD͒ have been optimized for high cw output power by incorporating a broad waveguide design. Increasing the optical-confinement layer total thickness from 0.2 to 1.0 m decreases the internal loss fivefold to 1.0-1.5 cm Ϫ1 , and doubles the transverse spot size to 0.6 m ͑full width half-maximum͒. Consequently, 4-mm long, 100-m-aperture devices emit up to 8.1 W front-facet cw power. cw power conversion efficiencies as high as 59% are obtained from 0.5-mm long devices. Catastrophic-optical-mirror-damage ͑COMD͒ power-density levels reach 15.0-15.5 MW/cm 2 , and are found similar to those for InGaAs/AlGaAs facet-coated diode lasers. © 1996 American Institute of Physics. ͓S0003-6951͑96͒01237-5͔Diode lasers with reliable operation in the 980 nm wavelength range are needed for applications such as pump sources for solid-state lasers or rare-earth-doped fiber amplifiers, and medical therapy. The growth of InGaAsP alloys lattice-matched to a GaAs substrate is very attractive as an aluminum-free alternative to the conventional AlGaAs-based materials. The aluminum-free InGaAs͑P͒/InGaP/GaAs material system has several advantages over the GaAs/AlGaAs material system for the realization of reliable, high-power diode laser sources: ͑1͒ the low reactivity of InGaP to oxygen facilitates regrowth for the fabrication of single-mode index-guided structures, 1,2 ͑2͒ higher electrical 3,4 and thermal conductivity 5 compared with AlGaAs, ͑3͒ potential for improved reliability, 6 and ͑4͒ potential for growth of reliable diode lasers on Si substrates. 7 Here, we report on the optimization of InGaAs/InGaAsP/InGaP strained-layer quantum well laser structures by using the broad-waveguide concept, 8,9 for maximizing the cw output power. As a result, record cw performances ͑8.1 W front-facet power, cavity length Lϭ4 mm; and 59% wallplug efficiency, Lϭ0.5 mm͒ are obtained from broad-area ͑100-m wide stripe͒ devices. Catastrophic optical mirror damage ͑COMD͒ values from LR/HR facet-coated devices under cw operation ͑i.e., ϳ15 MW/cm 2 ) are found to be similar to those for InGaAs/ AlGaAs facet-coated lasers, indicating that the quantum-well material ͑i.e., strained-layer InGaAs͒, and not the cladding/ confinement layers material, primarily determines the COMD value.The cw output power of a diode laser is generally limited by either thermal rollover or COMD. Thermally limited power saturation can be eliminated by designing laser structures to have high total power conversion efficiencies, low threshold-current density, and weak temperature sensitivity for both the threshold current and the external differential quantum efficiency ͑i.e., high T 0 and T 1 values͒. 4 As previously reported, 4 the use of a double-quantum-well ͑DQW͒ InGaAs active region together with high-band-gap InGaAsP (E g ϭ1.62 eV͒ optical-confinement layers, leads to 0.98 m diode lasers with relatively temperature insensitive characteristics. Given a certain CO...
By incorporating a broad transverse waveguide ͑1.3 m͒ in 0.97-m-emitting InGaAs͑P͒/InGaP/ GaAs separate-confinement-heterostructure quantum-well diode-laser structures we obtain record-high continuous-wave ͑cw͒ output powers for any type of InGaAs-active diode lasers: 10.6-11.0 W from 100-m-wide-aperture devices at 10°C heatsink temperature, mounted on either diamond or Cu heatsinks. Built-in discrimination against the second-order transverse mode allows pure fundamental-transverse-mode operation ( Ќ ϭ36°) to at least 20-W-peak pulsed power, at 68ϫthreshold. The internal optical power density at catastrophic optical mirror damage ͑COMD͒ P COMD is found to be 18-18.5 MW/cm 2 for these conventionally facet-passivated diodes. The lasers are 2-mm-long with 5%/95% reflectivity for front/back facet coating. A low internal loss coefficient (␣ i ϭ1 cm Ϫ1 ) allows for high external differential quantum efficiency d ͑85%͒. The characteristic temperatures for the threshold current T 0 and the differential quantum efficiency T 1 are 210 and 1800 K, respectively. Low differential series resistance R s : 26 m⍀; leads to electrical-to-optical power conversion efficiencies in excess of 40% from 1 W up to 10.6 W cw output power, and as much as 50% higher than those of 0.97-m-emitting Al-containing devices. © 1998 American Institute of Physics. ͓S0003-6951͑98͒03335-X͔ Broad-stripe, InGaAs-active diode lasers ͑ ϭ0.89-1.06 m͒ are routinely used for pumping solid-state fiber lasers, frequency doubling, and for numerous medical applications. Al-free devices ͑i.e., InGaAs/InGaP/GaAs structures͒ have superior ''wallplug'' efficiency compared with conventional Al-containing devices 1 due to their low differential series resistance. 1,2 Furthermore, the low oxidation rate of InGaP permits high-quality epitaxial regrowths over gratings for longitudinal-mode control ͑i.e., distributed-feedback lasers͒ 3,4 or over etched structures for lateral-mode control. 5-9 Thus, the Al-free material system is highly desirable for both broad-stripe spatially incoherent devices as well as for temporally and/or spatially coherent index-guided diode lasers.Recently, we have reported 10 continuous-wave ͑cw͒ output powers of 8 W from 0.98-m-emitting InGaAs/InGaP/ GaP lasers of a 100-m-wide stripe, 4-mm-long cavity, 1-m-thick transverse waveguide, and mounted on Cu heatsinks. Such broad-waveguide ͑BW͒ devices also demonstrated fundamental-transverse-mode operation to high drive levels, 11 as expected since the cutoff thickness for the second-order transverse mode is 1.05 m. BW devices with a waveguide thickness of 1.3 m exhibited lasing in both the fundamental and the second-order transverse modes. 12 We report here maximum cw output powers of 10.6-11 W, record-high values for any type of InGaAs-active-region diode lasers. The devices show pure fundamental-transversemode operation to at least 20 W peak pulsed power. We achieve these results using a 1.3-m-waveguide structure, designed to suppress oscillation of the second-order transverse mode.The InGaAs͑P͒/In...
Mid-infrared (λ=3.25 μm) broadened-waveguide diode lasers with active regions consisting of 5 type-II “W” quantum wells operated in continuous-wave (cw) mode up to 195 K. At 78 K, the threshold current density was 63 A/cm2, and up to 140 mW of cw output power was generated. A second structure with ten quantum wells operated up to 310 K in pulsed mode.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.