Pub Date : 2018-10-03DOI: 10.1007/978-3-030-23303-7
K. W. Böer, U. W. Pohl
{"title":"Superconductivity","authors":"K. W. Böer, U. W. Pohl","doi":"10.1007/978-3-030-23303-7","DOIUrl":"https://doi.org/10.1007/978-3-030-23303-7","url":null,"abstract":"","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2018-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85549026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Haché, Y. Kostoulas, R. Atanasov, J. Fraser, J. Sipe, H. V. van Driel
Historically, phase has received little attention as a parameter which can be used to control the properties of matter. Recently, however, coherence control of physical and chemical properties of simple systems using two or more laser beams has been demonstrated [1-3]. The possibility of influencing the phase of matter by controlling the phase of light arises from the fact that two or more phased perturbations which can connect the same initial and final states in a system can lead to interference effects between the different quantum mechanical pathways and therefore influence the final state of matter. In this talk we report two manifestations of this effect in bulk semiconductors, namely the generation and control of carrier density and electrical currents [3] in a bulk, unbiased semiconductor when both initial and final states are in the continuum (valence and conduction bands). The observations of such effects is not only intellectually appealing but may point the way to novel device applications. In initial experiments, control has been achieved in GaAs at room temperature using picosecond and 100 fs optical pulses at 1550 and 775 nm. The talk will focus on the description of these phenomena in terms of quantum mechanics as well as nonlinear optics. The influence of beam parameters and sample characteristics will be discussed.
{"title":"Coherent Control Of Semiconductor Optoelectronic Properties","authors":"A. Haché, Y. Kostoulas, R. Atanasov, J. Fraser, J. Sipe, H. V. van Driel","doi":"10.1364/qo.1997.qwb.3","DOIUrl":"https://doi.org/10.1364/qo.1997.qwb.3","url":null,"abstract":"Historically, phase has received little attention as a parameter which can be used to control the properties of matter. Recently, however, coherence control of physical and chemical properties of simple systems using two or more laser beams has been demonstrated [1-3]. The possibility of influencing the phase of matter by controlling the phase of light arises from the fact that two or more phased perturbations which can connect the same initial and final states in a system can lead to interference effects between the different quantum mechanical pathways and therefore influence the final state of matter. In this talk we report two manifestations of this effect in bulk semiconductors, namely the generation and control of carrier density and electrical currents [3] in a bulk, unbiased semiconductor when both initial and final states are in the continuum (valence and conduction bands). The observations of such effects is not only intellectually appealing but may point the way to novel device applications. In initial experiments, control has been achieved in GaAs at room temperature using picosecond and 100 fs optical pulses at 1550 and 775 nm. The talk will focus on the description of these phenomena in terms of quantum mechanics as well as nonlinear optics. The influence of beam parameters and sample characteristics will be discussed.","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72839681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multi-wavelength integrated light sources are key devices for future large scale wavelength division multiplexing (WDM) systems. One of important issues is precise control of lasing wavelength of each element. Large temperature sensitivity of lasing wavelength is also a remaining problem. Recently, wavelength stabilization of semiconductor lasers using strain was demonstrated [1]. Also, wavelength trimming technique was proposed for post-process precise control of wavelength [2].
{"title":"Wavelength Stabilization and Trimming Technologies for Vertical Cavity Surface Emitting Lasers","authors":"F. Koyama, K. Iga","doi":"10.1364/qo.1997.qthe.7","DOIUrl":"https://doi.org/10.1364/qo.1997.qthe.7","url":null,"abstract":"Multi-wavelength integrated light sources are key devices for future large scale wavelength division multiplexing (WDM) systems. One of important issues is precise control of lasing wavelength of each element. Large temperature sensitivity of lasing wavelength is also a remaining problem. Recently, wavelength stabilization of semiconductor lasers using strain was demonstrated [1]. Also, wavelength trimming technique was proposed for post-process precise control of wavelength [2].","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72873257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Interest in broken-gap, type-II heterostructures for optoelectronic applications is predicated largely on their promise as infrared lasers, detectors, and modulators appreciably outperforming conventional devices. Cryogenic imaging arrays based on these structures are projected to perform with higher detectivities and/or at higher operating temperatures than competing systems based on HgCdTe or extrinsic materials. Lasers in the 3-5μm spectral band are expected to operate at or near room temperature with significant output powers, and modulators with unusually low insertion losses and high dynamic range have been proposed. Brought to maturity, applications of such devices would be numerous, ranging from environmental monitoring systems to short-link, high bandwidth optical communications.
{"title":"Type-II Superlattices for Infrared Optoelectronics and Lasers","authors":"R. Miles, M. Flatté","doi":"10.1364/qo.1997.qfa.3","DOIUrl":"https://doi.org/10.1364/qo.1997.qfa.3","url":null,"abstract":"Interest in broken-gap, type-II heterostructures for optoelectronic applications is predicated largely on their promise as infrared lasers, detectors, and modulators appreciably outperforming conventional devices. Cryogenic imaging arrays based on these structures are projected to perform with higher detectivities and/or at higher operating temperatures than competing systems based on HgCdTe or extrinsic materials. Lasers in the 3-5μm spectral band are expected to operate at or near room temperature with significant output powers, and modulators with unusually low insertion losses and high dynamic range have been proposed. Brought to maturity, applications of such devices would be numerous, ranging from environmental monitoring systems to short-link, high bandwidth optical communications.","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75720711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semiconductor photonic crystals are promising candidates for realizing spontaneous emission control, i.e., enhancement of spontaneous emission rate (SER) and spontaneous emission factor. Schematic structure of various dimensions of photonic crystal and corresponding wave vector space inhibited by photonic bandgaps (PBGs) are summarized in Fig. 1. Due to the almost perfect PBG and single mode localized state, 3D structures are ideal. However, structures for optical wavelength range are still difficult to fabricate. We have studied 2D structures1,2) to confirm preliminary effects of photonic crystals. In this study, we simply predict the spontaneous emission control in 2D structures, and report the experiment to observe PBG in GaInAsP/InP 2D photonic crystals.
{"title":"Observation of Photonic Bandgap in GaInAsP/InP 2D Photonic Crystals by Equivalent Transmission Measurement","authors":"T. Baba, M. Ikeda, N. Kamizawa","doi":"10.1364/qo.1997.qtha.3","DOIUrl":"https://doi.org/10.1364/qo.1997.qtha.3","url":null,"abstract":"Semiconductor photonic crystals are promising candidates for realizing spontaneous emission control, i.e., enhancement of spontaneous emission rate (SER) and spontaneous emission factor. Schematic structure of various dimensions of photonic crystal and corresponding wave vector space inhibited by photonic bandgaps (PBGs) are summarized in Fig. 1. Due to the almost perfect PBG and single mode localized state, 3D structures are ideal. However, structures for optical wavelength range are still difficult to fabricate. We have studied 2D structures1,2) to confirm preliminary effects of photonic crystals. In this study, we simply predict the spontaneous emission control in 2D structures, and report the experiment to observe PBG in GaInAsP/InP 2D photonic crystals.","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88226517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Forward optical parametric oscillators (OPO’s) based on quasi-phase matching (QPM) were implemented in LiNbO3 [1], However, a forward OPO requires a cavity to establish oscillation. Harris [2] introduced the concept of a backward OPO (BOPO) based on conventional phase matching: a cavity is not required to establish oscillation. However, in Ref. [2], only a threshold condition was obtained. Here, we present our results on BOPO’s [3] and transversely-pumped counter-propagating OPO’s (TPCOPO’s) [4]. A TPCOPO does not require a cavity to establish oscillation either. Second-order susceptibility of a nonlinear medium is spatially modulated with a period the pump wavelength in the medium to achieve QPM. A pump wave at the wavelength in vacuum λ3 propagates along a waveguide for a BOPO or onto the surface for a TPCOPO. Two counter-propagating waves at the wavelengths λ1 and λ2 can be generated in the nonlinear medium. To tune the output frequencies of the signal and idler, we can change the incident angle of the pump wave in the TPCOPO or BOPO. The gain for the signal or idler is effectively balanced by the loss of the signal or idler at the respective exit plane to reach a steady-state oscillation. Because a cavity is eliminated, a BOPO or TPCOPO is more stable while a forward OPO is sensitive to the slight mirror translation. For a TPCOPO [4], there is an optimal pump power ≈3.4Pth (where Pth is the threshold, pump power) at which η reaches the maximum value of 44%. If P3≫Pth, there is a huge build-up of the oscillating fields inside the medium. The efficient sum-frequency generation saturates the TPCOPO. Consider GaAs/Al0.8Ga0.2 As multilayers [5] with the optimized structure dimensions: if λ3≈0.49μm, Pth≈7.3kW and tuning range: 1.4-2.6 μm (or 3.1-5.8 μm if λ3≈2μm). Consider ZnSe/ZnS multilayers: if λ3 ≈ 0.49 μm, Pth≈0.92kW and the tuning range: 0.7-1.7 μm, Consider GaAs/AlAs asymmetric coupled quantum-well domain structure [6]: if λ3 = 10 μm, Pth ≈ 10W and the tuning range: 15-29 μm. Consider a nondegenerate BOPO: |k1 − k2| ≫ 1/L, where k1,2 are the corresponding wave vectors and L is the length of the medium. If P3≈1.1 Pth, the conversion efficiency for the BOPO is η ≈ 20%. When P3 ≈ 3.4Pth, η ≈ 44% for the TPCOPO and η ≈ 95% for the BOPO. Consider a degenerate BOPO: λ1=λ2. A mirror for the pump wave with the reflectivity R2ω is attached to the right facet to increase the conversion efficiencies, However, it is not required for the oscillation to occur. When the pump intensity is Ip≈4I′th≈Ith/4, where Ith and I′th are the thresholds for a nearly-degenerate and degenerate BOPO, η ≈ 99.7% if R2ω=99%. Therefore, compared with the nondegenerate BOPO, the degenerate BOPO offers higher conversion efficiencies. The decrease of the conversion efficiency as Ip (>4I′th) increases is due to generation of a backward wave at the pump wavelength, which propagates along the direction opposite to that of the pump wave. Consider a poled LiNbO3 [1], If the spatia
{"title":"Novel configurations for optical parametric oscillators without any cavity","authors":"Yujie J. Ding, J. Khurgin, Seungjoon Lee","doi":"10.1364/qo.1997.qfd.4","DOIUrl":"https://doi.org/10.1364/qo.1997.qfd.4","url":null,"abstract":"Forward optical parametric oscillators (OPO’s) based on quasi-phase matching (QPM) were implemented in LiNbO3 [1], However, a forward OPO requires a cavity to establish oscillation. Harris [2] introduced the concept of a backward OPO (BOPO) based on conventional phase matching: a cavity is not required to establish oscillation. However, in Ref. [2], only a threshold condition was obtained. Here, we present our results on BOPO’s [3] and transversely-pumped counter-propagating OPO’s (TPCOPO’s) [4]. A TPCOPO does not require a cavity to establish oscillation either. Second-order susceptibility of a nonlinear medium is spatially modulated with a period the pump wavelength in the medium to achieve QPM. A pump wave at the wavelength in vacuum λ3 propagates along a waveguide for a BOPO or onto the surface for a TPCOPO. Two counter-propagating waves at the wavelengths λ1 and λ2 can be generated in the nonlinear medium. To tune the output frequencies of the signal and idler, we can change the incident angle of the pump wave in the TPCOPO or BOPO. The gain for the signal or idler is effectively balanced by the loss of the signal or idler at the respective exit plane to reach a steady-state oscillation. Because a cavity is eliminated, a BOPO or TPCOPO is more stable while a forward OPO is sensitive to the slight mirror translation. For a TPCOPO [4], there is an optimal pump power ≈3.4Pth (where Pth is the threshold, pump power) at which η reaches the maximum value of 44%. If P3≫Pth, there is a huge build-up of the oscillating fields inside the medium. The efficient sum-frequency generation saturates the TPCOPO. Consider GaAs/Al0.8Ga0.2 As multilayers [5] with the optimized structure dimensions: if λ3≈0.49μm, Pth≈7.3kW and tuning range: 1.4-2.6 μm (or 3.1-5.8 μm if λ3≈2μm). Consider ZnSe/ZnS multilayers: if λ3 ≈ 0.49 μm, Pth≈0.92kW and the tuning range: 0.7-1.7 μm, Consider GaAs/AlAs asymmetric coupled quantum-well domain structure [6]: if λ3 = 10 μm, Pth ≈ 10W and the tuning range: 15-29 μm. Consider a nondegenerate BOPO: |k1 − k2| ≫ 1/L, where k1,2 are the corresponding wave vectors and L is the length of the medium. If P3≈1.1 Pth, the conversion efficiency for the BOPO is η ≈ 20%. When P3 ≈ 3.4Pth, η ≈ 44% for the TPCOPO and η ≈ 95% for the BOPO. Consider a degenerate BOPO: λ1=λ2. A mirror for the pump wave with the reflectivity R2ω is attached to the right facet to increase the conversion efficiencies, However, it is not required for the oscillation to occur. When the pump intensity is Ip≈4I′th≈Ith/4, where Ith and I′th are the thresholds for a nearly-degenerate and degenerate BOPO, η ≈ 99.7% if R2ω=99%. Therefore, compared with the nondegenerate BOPO, the degenerate BOPO offers higher conversion efficiencies. The decrease of the conversion efficiency as Ip (>4I′th) increases is due to generation of a backward wave at the pump wavelength, which propagates along the direction opposite to that of the pump wave. Consider a poled LiNbO3 [1], If the spatia","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90588077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In ultrafast nonlinear spectroscopy interferometric techniques can be applied both for heterodyne detection of the signal and for the excitation of the sample by phase-locked pulses, thus delivering coherent control [1] over the system. Such techniques have been predicted to be extremely sensitive with respect to the dynamics of elementary excitation [2] and have been applied to the study of non-Markovian dynamics of molecules [3, 4]. For the case of semiconductors, interferometric sensitivity has been employed for detection purposes [5] and the use of phase-locked pulses has been reported quite recently [6]. In this paper we report the observation of a novel interference phenomenon in interferometric four-wave-mixing due to contributions beyond the third order perturbational limit. An analysis of the observed interferences allows for an estimation of the importance of these higher order contributions.
{"title":"Interferometrie Four-Wave-Mixing Spectroscopy on Semiconductors","authors":"M. Wehner, J. Hetzler, M. Wegener","doi":"10.1364/qo.1997.qwb.2","DOIUrl":"https://doi.org/10.1364/qo.1997.qwb.2","url":null,"abstract":"In ultrafast nonlinear spectroscopy interferometric techniques can be applied both for heterodyne detection of the signal and for the excitation of the sample by phase-locked pulses, thus delivering coherent control [1] over the system. Such techniques have been predicted to be extremely sensitive with respect to the dynamics of elementary excitation [2] and have been applied to the study of non-Markovian dynamics of molecules [3, 4]. For the case of semiconductors, interferometric sensitivity has been employed for detection purposes [5] and the use of phase-locked pulses has been reported quite recently [6]. In this paper we report the observation of a novel interference phenomenon in interferometric four-wave-mixing due to contributions beyond the third order perturbational limit. An analysis of the observed interferences allows for an estimation of the importance of these higher order contributions.","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84984209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, low-dimensional quantum structures such as quantum dots (QDs) and quantum wires (QWIs), has been attracting much interest due to their novel physical properties and consequent improvements in device performances.1) When the ideal QD or QWI structures are achieved, higher gain and lower threshold current in laser diodes are expected.2) Among the many fabrication methods reported for such structures, self-assembled quantum-dot (SAQD) growth techniques3-5) are particularly notable. They positively utilize the islanding growth in highly strained heteroepitaxial systems, such as InGaAs on GaAs. The SAQDs can be simply fabricated by molecular beam epitaxy (MBE)3) or metal-organic vapor phase epitaxy (MOVPE)4),5) and they have high crystal quality and uniform size distributions of within 10% as well as high surface densities of more than about 1011cm-2. Using these SAQDs, low-threshold QD edge-emitting lasers have been fabricated.6-8) We expect to make even more advanced lasers, such as QD vertical-cavity surface-emitting lasers (VCSELs) using QDs in the active region.9) The QD-VCSEL is especially attractive for controlling both the electron and photon modes in a microcavity structure.10) When the cavity mode coincides with the narrow bandwidth light emission that originates from the delta-function-like density of states in uniform QDs, a high-performance light source with very low threshold current can be realized. On the other hand, the gain width, which critically determines the temperature characteristics of the VCSEL,11) can be designated in QD-VCSELs by controlling the dot size distribution. Therefore, for improving and modifying device performances, we believe that the QD-VCSEL is the optimum optical device utilizing the QD structure. In this article, we report the fabrication of a QD-VCSEL and the observation of lasing oscillation at room temperature.
{"title":"Vertical cavity surface emitting laser with self-assembled quantum dots","authors":"K. Nishi, H. Saito, S. Sugou","doi":"10.1364/qo.1997.qwa.2","DOIUrl":"https://doi.org/10.1364/qo.1997.qwa.2","url":null,"abstract":"Recently, low-dimensional quantum structures such as quantum dots (QDs) and quantum wires (QWIs), has been attracting much interest due to their novel physical properties and consequent improvements in device performances.1) When the ideal QD or QWI structures are achieved, higher gain and lower threshold current in laser diodes are expected.2) Among the many fabrication methods reported for such structures, self-assembled quantum-dot (SAQD) growth techniques3-5) are particularly notable. They positively utilize the islanding growth in highly strained heteroepitaxial systems, such as InGaAs on GaAs. The SAQDs can be simply fabricated by molecular beam epitaxy (MBE)3) or metal-organic vapor phase epitaxy (MOVPE)4),5) and they have high crystal quality and uniform size distributions of within 10% as well as high surface densities of more than about 1011cm-2. Using these SAQDs, low-threshold QD edge-emitting lasers have been fabricated.6-8) We expect to make even more advanced lasers, such as QD vertical-cavity surface-emitting lasers (VCSELs) using QDs in the active region.9) The QD-VCSEL is especially attractive for controlling both the electron and photon modes in a microcavity structure.10) When the cavity mode coincides with the narrow bandwidth light emission that originates from the delta-function-like density of states in uniform QDs, a high-performance light source with very low threshold current can be realized. On the other hand, the gain width, which critically determines the temperature characteristics of the VCSEL,11) can be designated in QD-VCSELs by controlling the dot size distribution. Therefore, for improving and modifying device performances, we believe that the QD-VCSEL is the optimum optical device utilizing the QD structure. In this article, we report the fabrication of a QD-VCSEL and the observation of lasing oscillation at room temperature.","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88470218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Deveaud, S. Haacke, M. Hartig, R. Ambigapathy, I. B. Joseph, R. A. Taylor
Luminescence has been quite widely used for the study of semiconductor nanostructures, and more especially time resolved luminescence, due to the ease to get a luminescence signal. The interpretation of the results however is sometimes quite complex, and one generally finds that some care has to be taken for the results to be meaningful. In particular, the homogeneity of the excited density over the detected luminescence signal is a quite important parameter, also it is often desirable to work at the lowest possible densities.
{"title":"Femtosecond luminescence of semiconductor nanostructures","authors":"B. Deveaud, S. Haacke, M. Hartig, R. Ambigapathy, I. B. Joseph, R. A. Taylor","doi":"10.1364/qo.1997.qthd.2","DOIUrl":"https://doi.org/10.1364/qo.1997.qthd.2","url":null,"abstract":"Luminescence has been quite widely used for the study of semiconductor nanostructures, and more especially time resolved luminescence, due to the ease to get a luminescence signal. The interpretation of the results however is sometimes quite complex, and one generally finds that some care has to be taken for the results to be meaningful. In particular, the homogeneity of the excited density over the detected luminescence signal is a quite important parameter, also it is often desirable to work at the lowest possible densities.","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82794675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Filipowitz, U. Marti, M. Glick, F. Reinhart, J. Wang, P. von Allmen, J. Leburton
Theoretical predictions1 have shown that confined structures, quantum wires (QWR) or quantum dots (QD), should have higher gain and absorption, compared to quantum wells, owing to the discontinuity in the joint density of states. We use a non standard description of the valence band states2 to evaluate the absorption of V-shaped quantum wires close to the band edge. We choose the projection axis of the angular momentum of the valence band states along the non-confined direction of the wire. This description has two advantages: (i) the masses are isotropic along the two confined directions and (ii) the light hole (lh) and heavy hole (hh) states are decoupled at kz=0, if the kinetic energy of the confined holes is the same along both confined directions and the energy separation between the {lh,hh}i and {lh,hh}i+1 subbands is high. This description is particularly advantageous close to the band edge where transitions are mostly excitonic. Photoluminescence (PL) and photoluminescence excitation (PLE) measurements made on V-shaped quantum wires are reinterpreted: the lowest energy transition is a e1-lh1 excitonic transition and the second lowest is a e1-hh1 excitonic transition. This new interpretation is the first to explain the lower intensity of the lowest energy peak observed in PL and PLE measurements. To assess the impact of the non-uniformity of the wires, we evaluate the absorption of V-shaped QWR (V-QWR) grown by MBE deposition over a non-planar substrate3.
{"title":"New interpretation of quantum wire luminescence using a non standard description of the valence band states","authors":"F. Filipowitz, U. Marti, M. Glick, F. Reinhart, J. Wang, P. von Allmen, J. Leburton","doi":"10.1364/qo.1997.qthe.4","DOIUrl":"https://doi.org/10.1364/qo.1997.qthe.4","url":null,"abstract":"Theoretical predictions1 have shown that confined structures, quantum wires (QWR) or quantum dots (QD), should have higher gain and absorption, compared to quantum wells, owing to the discontinuity in the joint density of states. We use a non standard description of the valence band states2 to evaluate the absorption of V-shaped quantum wires close to the band edge. We choose the projection axis of the angular momentum of the valence band states along the non-confined direction of the wire. This description has two advantages: (i) the masses are isotropic along the two confined directions and (ii) the light hole (lh) and heavy hole (hh) states are decoupled at kz=0, if the kinetic energy of the confined holes is the same along both confined directions and the energy separation between the {lh,hh}i and {lh,hh}i+1 subbands is high. This description is particularly advantageous close to the band edge where transitions are mostly excitonic. Photoluminescence (PL) and photoluminescence excitation (PLE) measurements made on V-shaped quantum wires are reinterpreted: the lowest energy transition is a e1-lh1 excitonic transition and the second lowest is a e1-hh1 excitonic transition. This new interpretation is the first to explain the lower intensity of the lowest energy peak observed in PL and PLE measurements. To assess the impact of the non-uniformity of the wires, we evaluate the absorption of V-shaped QWR (V-QWR) grown by MBE deposition over a non-planar substrate3.","PeriodicalId":44695,"journal":{"name":"Semiconductor Physics Quantum Electronics & Optoelectronics","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85298785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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