Gain characteristics of strained quantum well lasers

Welch, David; Streifer, W.; Schaus, C.F.; Sun, S. Z.; Gourley, P. L.

doi:10.1063/1.102647

Cited by 75 publications

(6 citation statements)

References 14 publications

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“…It is 2.7 times higher than the best published data 16,17 for 0.96-0.98 m lasers, and well surpasses the best results from 100-m-aperture GaAs/AlGaAs devices with nonabsorbing mirrors. 18 The measured COMD values for the Al-free broad-waveguide-type lasers are found to be 15-15.5 MW/cm 2 , and are shown in Fig.…”

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confidence: 41%

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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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confidence: 41%

“…18 The measured COMD values for the Al-free broad-waveguide-type lasers are found to be 15-15.5 MW/cm 2 , and are shown in Fig. 5 together with those for InGaAs/AlGaAs 100-m-wide-stripe devices 16,19 as a function of the equivalent spot size, d/⌫. Interestingly, the COMD values do not appear to depend on the type of cladding or confining layer materials.…”

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confidence: 99%

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 note in particular that the p maximum occurs at 8ϫI th , a value quite close to that calculated using theory 18 ͑i.e., 9.5ϫI th ͒ with the measured R s value. It is also worth noting that the record output power achieved here from uncoated devices is the same as the highest output power previously demonstrated 19 from optimized facet-coated InGaAs/AlGaAs diode lasers with passivated mirror facets.…”

Section: Fig 2 Measured Characteristic Temperature Coefficientssupporting

confidence: 58%

High continuous wave output power InGaAs/InGaAsP/InGaP diode lasers: Effect of substrate misorientation

Mawst

Bhattacharya

Nesnidal

et al. 1995

Applied Physics Letters

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3 W cw output power has been obtained from aluminum-free, strained-layer double-quantum well ͑DQW͒ InGaAs/InGaAsP/InGaP uncoated, 100-m-wide stripe diode lasers ͑ϭ0.945 m͒ grown by low-pressure MOCVD on exact ͑100͒ GaAs substrates. The combination of high-band-gap ͑1.62 eV͒ InGaAsP confinement layers and the DQW structure provides relatively weak temperature dependence for both the threshold current I th as well as the external differential quantum efficiency d . Furthermore, the series electrical resistance for 100 mϫ600 m stripe-contact devices is as low as 0.12 ⍀. As a result, the power conversion efficiency reaches a maximum of 40% at 8 ϫI th , and decreases to only 33% at the maximum power ͑i.e., 3 W͒ at 28ϫI th . Low-temperature ͑12 K͒ photoluminescence measurements of InGaAs/InGaAsP quantum-well structures exhibit narrow linewidths ͑Ͻ10 meV͒ for material grown on exact ͑100͒ GaAs substrates, while growths on misoriented substrates exhibit linewidth broadening, as a result of ''step bunching.'' Laser structures grown on misoriented substrates exhibit increased temperature sensitivity of both I th and d , compared with structures grown on exact ͑100͒ substrates. © 1995 American Institute of Physics.Strained-layer quantum-well InGaAs lasers ͑980 nm͒ are needed as high-output-power pump sources for Er-doped fiber and waveguide amplifiers as well as for fluoride-fiberbased frequency upconversion. The use of the aluminum-free InGaAs/InGaAsP/InGaP material system has several advantages over the InGaAs/GaAs/AlGaAs material system for the realization of reliable, high-power diode 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 and thermal conductivity compared with AlGaAs, 3 and ͑3͒ lasers with AlGaAs cladding layers and unpassivated facets show higher facet degradation than similar lasers with InGaP cladding layers, 4 presumably due to the lower surface recombination velocity of InGaP 5 compared with AlGaAs. Al-free lasers also exhibit an order of magnitude lower facet temperature rise compared with devices containing AlGaAs in both the confining and cladding layers. 6 Although high performance has been demonstrated from Al-free laser structures, the characterization of the quantum-well growth for this material system and its influence on device performance have not been established.Achieving high cw output power requires weak temperature dependence of both the threshold current, I th , and differential quantum efficiency, d which in turn are influenced by carrier leakage from the quantum well͑s͒. Al-free lasers with GaAs or low-band-gap InGaAsP confinement layers exhibit strong carrier leakage from the InGaAs quantum well to the ͑optical͒ confinement layers, resulting in a strong temperature dependence of both I th and d . [7][8][9] To circumvent this problem, the use of higher band-gap InGaAsP confinement layers and multiple quantum wells have been used to reduce carrier leakage, and thereby reduce temp...

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“…6,7 The active region of the MQW layers, sitting between the p-type and n-type layer, is the area of great irradiation. This active region is the main topic in this experiment.…”

Section: Methodsmentioning

confidence: 99%

True near-field optical characters of a GaAlAs semiconductor laser diode

Chen

Tsai

Chen

et al. 1999

Review of Scientific Instruments

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In this research we have taken advantage of near-field scanning optical microscopy, a recently developed technique, to test the optical nature of GaAlAs semiconductor laser diodes working at 780 nm. With this method, both the images of the topographic and the near-field intensity of the laser diodes can be simultaneously obtained. With the obtained results, we can analyze the variety of the geometric structure, the local near-field optical intensity, the propagating modes, and the near-field mode-field diameter at different working states of the laser diodes. Hereby, we can find the factors that affected the radiation cavity of the laser diode and explore its alive state.

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Gain characteristics of strained quantum well lasers

Cited by 75 publications

References 14 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 output power InGaAs/InGaAsP/InGaP diode lasers: Effect of substrate misorientation

True near-field optical characters of a GaAlAs semiconductor laser diode

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