High-power operation of low-confinement laser-diode structure

Petrescu-Prahova, I.B.; Buda, M.; Iordache, G.; Karouta, F.; Smalbrugge, E.; Roer, T.G. van de; Kaufmann, L.M.F.; Wolter, J.H.; Vleuten, W.C. van der

doi:10.1117/12.203458

Cited by 4 publications

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“…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.…”

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“…The subsequent decrease in the ͑trans-verse͒ optical confinement factor, ⌫, can be offset by increasing the device cavity length, L, in structures of low internal loss, ␣ i (Ͻ2 cm Ϫ1 ). 8,9 Thus, a large optical spot size can be obtained with little penalty in threshold-current density or efficiency. 9 The Al-free DQW laser structure with a broad waveguide is shown in Fig.…”

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8 W continuous wave front-facet power from broad-waveguide Al-free 980 nm diode lasers

Mawst

Bhattacharya

Lopez

et al. 1996

Applied Physics Letters

166

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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...

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8 W continuous wave front-facet power from broad-waveguide Al-free 980 nm diode lasers

Mawst

Bhattacharya

Lopez

et al. 1996

Applied Physics Letters

166

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“…We have designed and fabricated high-power, efficient, Al-free active-region devices by employing two features: ͑high-band gap͒ cladding layers of In 0.5 ͑Ga 0.5 Al 0.5 ͒ 0.5 P and the ''broad-waveguide'' concept. 9,10 The former significantly reduces carrier leakage, while the latter insures both a low internal loss coefficient, ␣ i (ϳ2 cm Ϫ1 ), since a large fraction of the optical energy is contained within the not intentionally doped ͑i.e., low loss͒ waveguide, 10 as well as a large transverse spot size ͑0.5 m full-width at half-maximum͒. As a result, we report the lowest J th ͑220 A/cm 2 for 1-mm-long devices͒ for 0.8 m band, Al-free diode lasers as well as a record-high T 0 ͑160 K͒.…”

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High continuous wave power, 0.8 μm-band, Al-free active-region diode lasers

Wade

Mawst

Botez

et al. 1997

Applied Physics Letters

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Efficient, high-power, Al-free active-region diode lasers emitting at ϭ0.83 m have been grown by low-pressure metalorganic chemical vapor deposition. Threshold-current densities as low as 220 A/cm 2 , maximum continuous wave ͑cw͒ power of 4.6 W, and a maximum cw wallplug efficiency of 45% are achieved from 1 mm long, uncoated devices with In 0.5 ͑Ga 0.5 Al 0.5 ͒ 0.5 P cladding layers. Further improvement is obtained by replacing the p-In 0.5 ͑Ga 0.5 Al 0.5 ͒ 0.5 P cladding layer with thin ͑0.1 m͒ electron-blocking layers of Al 0.85 Ga 0.15 As and In 0.5 ͑Ga 0.5 Al 0.5 ͒ 0.5 P, and a pIn 0.5 ͑Ga 0.9 Al 0.1 ͒ 0.5 P cladding layer. Such devices provide a record-high T 0 of 160 K and reach catastrophic optical mirror damage ͑COMD͒ at a record-high cw power of 4.7 W ͑both facets͒. The corresponding COMD power-density level ͑8.7 MW/cm 2 )is ϳ2 times the COMD power-density level for uncoated, 0.81-m-emitting AlGaAs-active devices. Therefore, 0.81-m-emitting, Al-free active-region devices are expected to operate reliably at roughly twice the power of AlGaAs-active region devices. © 1997 American Institute of Physics. ͓S0003-6951͑97͒04302-7͔High-power diode lasers emitting in the wavelength range ϭ0.8-0.87 m are of interest because of important applications such as pump sources for Nd:YAG lasers. Such lasers conventionally use AlGaAs in the active region for р0.84 m, and thus suffer from short lifetimes and limited output powers by comparison to GaAs-active-region devices. The quaternary alloys InGa͑As͒P, lattice matched to GaAs, offer an attractive alternative to the AlGaAs/GaAs material system because: ͑1͒ the potential for better reliability, due to their inherent resistance to the formation of dark-line defects 1 and lower surface recombination velocity of InGaAsP compared to AlGaAs; 2 ͑2͒ a smaller increase in facet temperature 1 with drive current, and ͑3͒ the potential for growing reliable diode lasers on Si substrates. 3 However, the InGaAsP/GaAs material system has small conduction-band offsets, which cause diode lasers made of such material to suffer from massive carrier leakage. As a result, one obtains a relatively high threshold-current density, J th ; 1,4,5 low internal efficiency, i ; 5,6 and low threshold-current characteristic temperature, T 0 . 5,7 A recent attempt to solve the problem of carrier leakage 8 has been the use of high-band-gap material ͑Al 0.7 Ga 0.3 As͒ for the cladding layers which delivered high T 0 , promising reliability data, but also relatively high J th . We have designed and fabricated high-power, efficient, Al-free active-region devices by employing two features: ͑high-band gap͒ cladding layers of In 0.5 ͑Ga 0.5 Al 0.5 ͒ 0.5 P and the ''broad-waveguide'' concept. 9,10 The former significantly reduces carrier leakage, while the latter insures both a low internal loss coefficient, ␣ i (ϳ2 cm Ϫ1 ), since a large fraction of the optical energy is contained within the not intentionally doped ͑i.e., low loss͒ waveguide, 10 as well as a large transverse spot size ͑0.5 m full-width at hal...

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“…Experimental [1] Structures-We used three types of GaAs/AlGaAs laser structures epitaxially grown on n*+_GaAs substrates and a Zn p'tGaAs substrate. AZ 1350 photoresist 8 and 16 jim wide stripes were defined in <110> or <110> directions on the p-side of the wafer.…”

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confidence: 99%

Controlled Anodic Oxidation for High Precision Etch Depth in AlGaAs III‐V Semiconductor Structures

Buda

Smalbrugge

Geluk

et al. 1998

J. Electrochem. Soc.

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Controlled anodic oxidation for achieving a better control of etch depth in A1GaAs semiconductor structures is studied. The rates of material consumption and oxide thickness growth for p'GaAs and p-Al0 ,,Ga,,,As are given for the citric acid/glycol/water electrolyte. The etch profiles for GaAs/Al, 45Ga,,,As and GaAs/A1,,,Ga,40As layer sequences in laser diode structures are presented. The underetch is rather high and depends on oxidation conditions (constant voltage or constant current). The profile obtained is very rough for constant voltage oxidation and much better when using constant current conditions. The latter also improves the uniformity of oxide growth. The etch rate of the anodic oxide in diluted HC1 is much larger for GaAs than for AlGaAs.

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High-power operation of low-confinement laser-diode structure

Cited by 4 publications

References 0 publications

8 W continuous wave front-facet power from broad-waveguide Al-free 980 nm diode lasers

8 W continuous wave front-facet power from broad-waveguide Al-free 980 nm diode lasers

High continuous wave power, 0.8 μm-band, Al-free active-region diode lasers

Controlled Anodic Oxidation for High Precision Etch Depth in AlGaAs III‐V Semiconductor Structures

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