Wavelength dependence of gain saturation in GaAs lasers

Goebel, E. O.; Hildebrand, O.; Löhnert, K.

doi:10.1109/jqe.1977.1069243

Cited by 59 publications

(12 citation statements)

References 31 publications

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“…1(a). The red-shift to the gain spectrum is consistent with the theoretical results of the interplay between photon and carrier densities [9]. However, here carriers can also be captured by localized states at the same time so that it is difficult to distinguish between the two competing emission mechanisms.…”

Section: Resultssupporting

confidence: 85%

“…absorption, occurs after 2 ps at short wavelengths due to a decrease of the edge emission at this 50 µm stripe length. This transient absorption is analogous to the absorption at short wavelengths in the case of long stripes as explained by a reduction in the chemical potential below the corresponding photon energy [9]. For a long (350 µm) stripe, gain occurs much lower in energy, approximately 130 meV below the emission energy observed for the 50 µm stripe.…”

Section: Resultsmentioning

confidence: 67%

“…As stripe length increases, gain is reduced. This stripe-length dependence of gain saturation is due to coupling of the carrier and photon densities [5,9]. Although gain for short and long stripe lengths become similar at long delay times (>17 ps), initial gain for a long stripe is significantly reduced.…”

Section: Resultsmentioning

confidence: 99%

“…Broadening of these lower energy spectra is enhanced. It has been reported that the carrier distribution along the stripe is inhomogeneous [5,9] so the net carrier density increases with stripe length. This large red-shift is therefore likely to be attributable to bandgap renormalization.…”

Section: Resultsmentioning

confidence: 99%

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Time‐resolved gain saturation dynamics in InGaN multi‐quantum well structures

Kyhm

Smith

Taylor

et al. 2004

phys. stat. sol. (c)

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Transient gain spectra were measured for an In 0.02 Ga 0.98 N / In 0.16 Ga 0.84 N multiple quantum well using the variable stripe length method (VSLM) in combination with the ultrafast optical Kerr gate (OKG) technique. Gain dynamics were measured for a range of excitation lengths from short (50 µm) to long (350 µm) stripes with the sample under femtosecond photoexcitation. Analysis of the temporal behaviour of gain and chemical potential suggests that stimulated emission originates from a photoexcited electronhole plasma at early times; at later times localized states dominate as the electron-hole plasma becomes exhausted. Gain reduction at early times is attributable to coupling of the electron-hole plasma with photons along the stripe, whilst localized states are less susceptible to gain saturation. . However, the physics of optical gain and stimulated emission has not been clearly resolved. Analysis of gain spectra is very useful in understanding the mechanisms responsible for stimulated emission and the VSLM is commonly used for this purpose. Conventional analysis had been limited to short stripe length regimes as it has proved difficult to find appropriate fitting functions [3]. In preliminary work, we presented an analysis method for VSLM data [5] that enables the calculation of stripe-length-dependent gain for longer stripe lengths. This analysis has been further extended by time-resolving the edge emission for different stripe lengths, from which it is possible to calculate the time-resolved gain spectrum. It has been reported that the primary mechanism for stimulated emission depends on the degree of electron/hole localization, which is mainly determined by the Inmole fraction [6]. In high In-content devices (>20 %), localized excitons play an important role in stimulated emission, while an electron-hole plasma becomes the dominant mechanism in low In-content devices. The sample investigated here is in the intermediate indium content range, which is likely to result in complicated dynamics since both localized states and electron hole plasma will play a role in stimulated emission. In this work, these two effects are investigated using transient gain spectra measurements. In particular, the carrier dynamics related to gain saturation effects in a longer stripe are discussed in terms of many-body effects and compared with the dynamics in a shorter stripe.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Time‐resolved gain saturation dynamics in InGaN multi‐quantum well structures

Kyhm

Smith

Taylor

et al. 2004

phys. stat. sol. (c)

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“…2 For example, the wavelength dependence of gain and saturation strongly results from the coupled carrier-photon system. 3 One of the most important parameters of an amplifier is the saturation length L s at which saturation starts to play a significant role for a certain gain g. The gL s product must be smaller than 5 to avoid gain saturation for GaAs-based structures. 4 However, this empirical law strongly depends on the amplifier material.…”

mentioning

confidence: 99%

Optical gain and saturation in nitride-based laser structures

Vehse

Michler

Lange

et al. 2001

Applied Physics Letters

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Time-Resolved Amplified Spontaneous Emission in InAs/GaAs Quantum Dots

Lingk

Plessen

Feldmann

et al. 2001

phys. stat. sol. (b)

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In this paper, we investigate the dynamics of amplified spontaneous emission (ASE) in self-assembled InAs/GaAs quantum dots. Upconversion is used to time-resolve the emission from an edge-emitting waveguide structure at room temperature which is excited by short laser pulses in a stripe geometry. We demonstrate that increases in both the electron-hole pair density and the stripe length significantly decrease the emission decay time from around 2 ns, corresponding to spontaneous emission, to about 0.9 ns, corresponding to stimulated emission or ASE. A simulation of the ASE process in this geometry is in agreement with our experimental results.

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Wavelength dependence of gain saturation in GaAs lasers

Cited by 59 publications

References 31 publications

Time‐resolved gain saturation dynamics in InGaN multi‐quantum well structures

Time‐resolved gain saturation dynamics in InGaN multi‐quantum well structures

Optical gain and saturation in nitride-based laser structures

Time-Resolved Amplified Spontaneous Emission in InAs/GaAs Quantum Dots

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