Optical gain and saturation in nitride-based laser structures

Vehse, Martin; Michler, Peter; Lange, Oliver; Rowe, M. W.; Gutowski, J.; Bäder, S.; Lugauer, Hans-Juergen; Brüderl, G.; Weimar, A.; Lell, A.; Härle, V.

doi:10.1063/1.1401780

Cited by 15 publications

(15 citation statements)

References 14 publications

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“…Both approaches yield a value of P tr to be around 70 kW/cm 2 . Characteristic gain parameter g 0 = 94 cm -1 is similar to the values measured for the laser diodes deposited on SiC and sapphire substrates [13,14]. Saturation behaviour changes for different photon energies (Fig.…”

Section: Gain Measurementmentioning

confidence: 86%

Optical gain and saturation behavior in homoepitaxially grown InGaN/GaN/AlGaN laser structures

Świetlik

Perlin

Suski

et al. 2007

Phys. Status Solidi (c)

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Optical gain and losses in semiconductor laser epilayers are of profound importance in device optimization. We used both parameters to estimate the potential of InGaN/GaN/AlGaN epitaxial system to be used as a laser structure emitting in a blue region. The sample was grown homoepitaxially by MOVPE technique on high quality bulk GaN substrates obtained in high pressure growth process. These structures are characterized by very low dislocation density (around 10 5 cm -2). As a result the reduction of a nonradiative recombination is expected which is reflected in reduced excitation pump power and gain saturation processes described by means of saturation length and a product of the latter and a maximum modal gain. To determine gain value and its saturation behavior a variable stripe length method is used employing one dimensional amplifier model. Maximum gain value of 190 cm -1 together with internal losses of 15 cmare determined for the studied structure. Low value of maximum saturation length of 320 um was found in our structures.

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Section: Gain Measurementmentioning

confidence: 86%

Optical gain and saturation behavior in homoepitaxially grown InGaN/GaN/AlGaN laser structures

Świetlik

Perlin

Suski

et al. 2007

Phys. Status Solidi (c)

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“…These values are mainly limited by the background absorption visible at lower energies where no absorption should occur in the ideal case. The product of modal gain maximum and saturation length is g mod L s = 0.75, which 2.6 2. is roughly one order of magnitude less compared to QW structures, where the product has been measured to be 4 -10 [23,25]. InGaN QWs reach values of g mod = 180 -300 cm -1 and L s = 250 -350 µm [21].…”

Section: Resultsmentioning

confidence: 99%

“…For guaranteeing success of the VLS method, saturation effects have to be avoided. One reason for saturation effects can be that the stripe length becomes too large [23,24]. In this case the light generated on the stripe end opposite to the emitting edge will no longer be amplified since all excited states have already been depleted by photons coming from nearer distances.…”

Section: Resultsmentioning

confidence: 99%

Optical properties and modal gain of InGaN quantum dot stacks

Kalden

Sebald

Gutowski

et al. 2009

Phys. Status Solidi (c)

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We present investigations of the optical properties of stacked InGaN quantum dot layers and demonstrate their advantage over single quantum dot layer structures. Measurements were performed on structures containing a single layer with quantum dots or threefold stacked quantum dot layers, respectively. A superlinear increase of the quantum dot related photoluminescence is detected with increasing number of quantum dot layers while other relevant GaN related spectral features are much less intensive when compared to the photoluminescence of a single quantum dot layer. The quantum dot character of the active material is verified by microphotoluminescence experiments at different temperatures. For the possible integration within optical devices in the future the threshold power density was investigated as well as the modal gain by using the variable stripe length method. As the threshold is 670 kW/cm 2 at 13 K, the modal gain maximum is at 50 cm -1 . In contrast to these limited total values, the modal gain per quantum dot is as high as 10 -9 cm -1 , being comparable to the II-VI and III-As compounds. These results are a promising first step towards bright low threshold InGaN quantum dot based light emitting devices in the near future.

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“…These values are mainly limited by the background absorption visible at lower energies where no absorption should occur in the ideal case. The product of modal gain maximum and saturation length is g mod L s ¼ 0.75, which is roughly one order of magnitude less compared to QW structures, where it has been measured to be 4-10 [68,70]. InGaN QWs reach values of g mod ¼ 180-300 cm À1 and L s ¼ 250-350 mm [67].…”

Section: Gainmentioning

confidence: 96%

“…To guarantee success of the VLS method, saturation effects have to be avoided. One reason for saturation effects can be that the stripe length becomes too large [68,69]. In this case the light generated on the stripe end opposite to the emitting edge will no longer be amplified since all excited states have already been depleted by photons coming from nearer distances.…”

Section: Gainmentioning

confidence: 96%

Optical properties of single InGaN quantum dots and their devices

Sebald

Kalden

Lohmeyer

et al. 2011

Physica Status Solidi (b)

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Nitride-based quantum dots have many attractive optical properties for the realization of quantum dot (QD) based devices which will be presented in this contribution. We will analyze the basic characteristics of single InGaN QDs and their electroluminescence (EL) as well as the optical properties of QD stacks and their gain spectra. The single QDs are characterized by the high temperature stability of their emission up to 150 K in PL and EL and even up to room temperature for stacked QD samples. Furthermore, the polarization of individual QD emission lines was analyzed giving an insight into their geometrical shape. Time-resolved microphotoluminescence (m-PL) measurements on the excitonic and biexcitonic transition of a single QD as well as on the influence of piezoelectric fields on them and on their binding energy were performed. Further, we present an analysis of electrically driven luminescence from single InGaN QDs embedded into a light emitting diode structure showing single sharp emission lines in the green spectral region with a high temperature stability up to 150 K. Furthermore, for the possible integration within optical devices in the future the threshold power density as well as the modal gain were investigated for samples with stacked InGaN QD layers. They show a modal gain per QD being comparable to that of II-VI and III-As compounds. These results give a good insight into the basic optical properties of InGaN QD based devices and showing their high potential for electrically driven single photon emitters as well as for bright, low-threshold InGaN QD based light emitting devices in the near future.

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Optical gain and saturation in nitride-based laser structures

Abstract: Influence of the barrier height on carrier recombination and transparency density in GaN-based laser structures

Cited by 15 publications

References 14 publications

Optical gain and saturation behavior in homoepitaxially grown InGaN/GaN/AlGaN laser structures

Optical gain and saturation behavior in homoepitaxially grown InGaN/GaN/AlGaN laser structures

Optical properties and modal gain of InGaN quantum dot stacks

Optical properties of single InGaN quantum dots and their devices

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