Random lasing in nanocrystalline ZnO powders

Kalt, H.; Fallert, J.; Dietz, R. J. B.; Sartor, Janos; Schneider, Daniel; Klingshirn, C.

doi:10.1002/pssb.200983268

Cited by 12 publications

(10 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pronounced minima in σ tot are another signature of gain and gain narrowing in the full polaritonic spectrum. Our results of lifetimes of excitons and exciton-polaritons are corroborated by the experimental findings of laser spectra in several setups of ZnO Mie resonators as well as in ZnO random lasers [20,21,[51][52][53][54][55], where, in either experiment, stable lasing modes at 3.13 eV have been found. In either system the spectral result is attributed to the coupling of the excited electronic subsystem of ZnO bulk to the resonator mode of the single scatterer.…”

Section: Resultssupporting

confidence: 87%

See 1 more Smart Citation

Quantum Many-Body Theory for Exciton-Polaritons in Semiconductor Mie Resonators in the Non-Equilibrium

Lubatsch

Frank

2020

Applied Sciences

View full text Add to dashboard Cite

We implement externally excited ZnO Mie resonators in a framework of a generalized Hubbard Hamiltonian to investigate the lifetimes of excitons and exciton-polaritons out of thermodynamical equilibrium. Our results are derived by a Floquet-Keldysh-Green's formalism with Dynamical Mean Field Theory (DMFT) and a second order iterative perturbation theory solver (IPT). We find that the Fano resonance which originates from coupling of the continuum of electronic density of states to the semiconductor Mie resonator yields polaritons with lifetimes between 0.6 ps and 1.45 ps. These results are compared to ZnO polariton lasers and to ZnO random lasers. We interpret the peaks of the exciton-polariton lifetimes in our results as a sign of gain narrowing which may lead to stable polariton lasing modes in the single excited ZnO Mie resonator. This form of gain may lead to polariton random lasing in an ensemble of ZnO Mie resonators in the non-equilibrium. PACS: 42.55.-f lasers; 71.10.-w theories and models of many-electron systems; 42.50.Hz strong-field excitation of optical transitions in quantum systems; multi-photon processes; dynamic Stark shift; 74.40+ Fluctuations; 03.75.Lm Tunneling, Josephson effect, Bose-Einstein condensates in periodic potentials, solitons, vortices, and topological excitations; 72.20.Ht high-field and nonlinear effects; 71.36.+c polaritons; 71.35.-y excitons and related phenomena; 42.55.Px semiconductor lasers, laser diodes; 89.75.-k complex systems

show abstract

Section: Resultssupporting

confidence: 87%

“…The coupling strength as such is characteristic for the formation of polaritons [38]. The results are derived for an external optical pump intensity of 2.4 MW/cm 2 which on the other side is a typical pump strength for solid state random lasers [51][52][53][54]. We find a sharp dip in the lifetimes of polaritonic states at the Fermi energy.…”

Section: Resultsmentioning

confidence: 79%

Quantum Many-Body Theory for Exciton-Polaritons in Semiconductor Mie Resonators in the Non-Equilibrium

Lubatsch

Frank

2020

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…Recent results of this topic including the observation of the coexistence of spatially extended and more confined modes are presented and discussed in Refs. 110, 111 and in an invited contribution 113 to this conference 112. For hints towards random lasing in disordered ensembles of nano rods see Ref 114.…”

Section: Stimulated Emissionmentioning

confidence: 98%

65 years of ZnO research – old and very recent results

Klingshirn

Fallert

Zhou

et al. 2010

Physica Status Solidi (b)

Self Cite

383

244

View full text Add to dashboard Cite

The research on ZnO has a long history but experiences an extremely vivid revival during the last 10 years. We critically discuss in this didactical review old and new results concentrating on optical properties but presenting shortly also a few aspects of other fields like transport or magnetic properties. We start generally with the properties of bulk samples, proceed then to epitaxial layers and nanorods, which have in many respects properties identical to bulk samples and end in several cases with data on quantum wells or nano crystallites. Since it is a didactical review, we present explicitly misconceptions found frequently in submitted or published papers, with the aim to help young scientists entering this field to improve the quality of their submitted manuscripts. We finish with an appendix on quasi two-and one-dimensional exciton cavity polaritons.

show abstract

“…Several experiments confirmed this view 2,9,10 , and tried to address the connection between the structure 11 pumping condition, or gain and the degree of localization [12][13][14] . The , whose spot is shaped by a SLM in amplitude configuration (by using the two crossed polarizers P1 and P2), pumps a single titanium dioxide cluster (diameter between 5 and 12 µm).…”

mentioning

confidence: 93%

Tunable degree of localization in random lasers with controlled interaction

2012

View full text Add to dashboard Cite

We show that the degree of localization for the modes of a random laser (RL) is affected by the inter mode interaction that is controlled by shaping the spot of the pump laser. By experimentally investigating the spatial properties of the lasing emission we infer that strongly localized modes are activated in the low interacting regime while in the strongly interacting one extended modes are found lasing. Thus we demonstrate that the degree o localization may be finely tuned at the micrometer level.PACS numbers: 42.25.Dd 07.05.Fb Keywords: Light localization, Random lasing RL are among the most complex systems in photonics, encompassing structural disorder and nonlinearity, 1 and ranging from micron sized optical cavities 2 to kilometerlong fibers 3 . Attention on this systems has been constantly growing as the number of potential applications, ranging from object coding 4 to speckle-free illumination 5 .First-principle time domain simulations show that modes of a RL arise from electromagnetic states [6][7][8] , that may appear in localized or extended fashion. Several experiments confirmed this view 2,9,10 , and tried to address the connection between the structure 11 pumping condition, or gain and the degree of localization 12-14 . The The pulsed laser (532 nm, repetition frequency 10 Hz and fluence 0.1nJ/µm 2 ), whose spot is shaped by a SLM in amplitude configuration (by using the two crossed polarizers P1 and P2), pumps a single titanium dioxide cluster (diameter between 5 and 12 µm). The RL emission is collected by a microscope objective (OBJ) to be imaged by using a beamsplitter (BS) in two different image planes. In one of them lies a fiber controlled by translators with nanometric resolution that allows the measurement of the spatio-spectral map. In this way it is possible to scan a magnified (50×) image of the sample and measure the spectra emitted from a single point. The fibre core (50 µm in diameter) collects spectra originating in an area of 1µm of diameter of the sample. The other light path allows imaging the sample on a CCD. presence of many modes may give rise to unique phenomena: in a linear system extended necklace states spread over the sample via multiple (localized) resonances 15 while in a system with gain the inter-mode coupling affects the whole spectrum generating mode repulsion 16 directly connected to the nonlinear interaction 17 .On the other hand it has been recently demonstrated that the inter-mode coupling plays a critical role in the onset of two fundamentally different RL regimes, distinguished by the shape of the emission: a "resonant feedback random laser" (RFRL) 18 , which appears as a set of sharp peaks oscillating independently at fixed spectral positions, and the "intensity feedback random laser" (IFRL) 19 , characterized by a smooth single line narrowed spectrum. By using a tailored spatial shape of the pump area 20,21 , a switching between the two can be achieved. In fact a RFRL is observed when activating a set of weakly interacting resonances while IFRL is produced un...

show abstract

Random lasing in nanocrystalline ZnO powders

Cited by 12 publications

References 23 publications

Quantum Many-Body Theory for Exciton-Polaritons in Semiconductor Mie Resonators in the Non-Equilibrium

Quantum Many-Body Theory for Exciton-Polaritons in Semiconductor Mie Resonators in the Non-Equilibrium

65 years of ZnO research – old and very recent results

Tunable degree of localization in random lasers with controlled interaction

Contact Info

Product

Resources

About