摘要:

Semiconductor nanocrystals are being extensively studied during last decade. In addition to basic issues like evolution of matter properties on the way from cluster to crystal, many-body phenomena in finite quantum systems and others, there are important practical challenges, e.g. temperature independent threshold current in lasers, novel light-emitting and nonlinear-optical materials and devices. It is important that electron confinement in nanocrystals can be easily combined with photon confinement when nanocrystals are embedded in a planar or spherical microcavity or in a periodic dielectric structure referred to as a photonic crystal. In the present paper we provide an overview of electron confinement effects in isolated nanocrystals and formation of collective electron states in close-packed arrays of nanocrystals. We shall discuss a possibility to obtain enhanced optical nonlinearities in nanocrystals and to develop novel mesoscopic structures based on nanocrystals embedded in a cavity or in a photonic crystal. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372724

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Using of structures with size quantization in all three directions, or quantum dots (QD’s) allows exciting possibilities in device engineering. Semiconductor heterostructures with self-organized QDs have experimentally exhibited properties expected for zero-dimensional systems. When used as active layer in the injection lasers, these advantages help to strongly increase material gain and differential gain, to improve temperature stability of the threshold current, and to provide improved dynamic properties. Optimization of deposition parameters can ensure that the self-organized islands are small (∼10 nm), have a similar size and shape and form dense arrays.Saturation material gainas high as 150000 cm−1as compared to QW values of about 3000 cm−1.Maximum differential gainreported for QD lasers approaches10−12&hthinsp;cm2and exceeds the QW laser values by about three orders of magnitude. Direct observation of relaxation oscillations reveals present cutoff frequencies close to 10 GHz. High internal (>96&percent;) and differential (70&percent;) efficiencies at 300 K are realized for QD lasers emitting in the 0.94–1.15 &mgr;m range. GaAs-based lasers for the 1.3 &mgr;m range with lowJth(80&hthinsp;A/cm2,cavity length 1.9 mm) at room temperature (RT) are realized using InAs/InGaAs/GaAs QDs obtained by activated spinodal decomposition. Differential efficiency is 55&percent; and internal losses are 1.5 cm−1. 3W CW operation at RT is achieved. 1.3 &mgr;m GaAs-based QD VCSELs (300 K,Ith=1.8&hthinsp;mA,&eegr;diff>40&percent;) are realized. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372725

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We discuss the optical properties of semiconductor microcavities. We introduce to both weak and strong coupling re´gimes of the light—matter interaction. We discuss in the first part the modifications of the radiative emission rate in the weak coupling re´gime. In a second part we will give an overview the physics of cavity—polariton features in the strong coupling re´gime. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372726

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The optical properties of self-similar optical multilayer structures are discussed when the input light intensity is so low to neglect any nonlinear effect. The considered structures are obtained by alternating two dielectric layers of different refractive indices such that to belong to some fractal set. The triadic Cantor and the Fibonacci sets are considered. Some applications of the field localization properties of such structures are discussed. Nonlinear behavior is also discussed. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372727

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Optical properties of fractal nano-structured composite materials, such as fractal aggregates of metal colloids and metal-dielectric films near the percolation threshold, are reviewed. It is shown that the fractal geometry results in localization of plasmon excitations in the “hot” spots, where the local field can exceed the applied field by several orders of magnitude. The high local fields of the localized fractal modes result in dramatic enhancement of optical responses, making feasible the surface-enhanced spectroscopy of single molecules and nanocrystals. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372728

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Pulse compression, second-harmonic generation, and spectral broadening of short light pulses in photonic crystals are discussed. The abilities of such structures to guide and localize light, phase-match nonlinear interactions, and to generate evanescent waves are explored. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372729

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372730

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A number of new physical phenomena have been predicted to occur near the band edge of one dimensional photonic band gap materials. Some of these phenomena include superluminal pulse propagation, group velocity slowing down, resonance tunneling through metal structures, nonlinear optical switching, and nonlinear frequency conversion, to name a few. In this paper we will discuss a pulse propagation method, resonance tunneling through metallo-dielectric multiplayer stacks, phase matching conditions and enhanced second harmonic generation, and a true time delay line. These effects are based on the linear properties of finite structures, which can be used to predict the nature of the nonlinear optical interactions. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372731

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A re-evaluation of the notions of group(Vg)and energy(Ve)velocities in finite photonic band gap structures leads us to conclude that the two velocities are related byVe=|t|2Vgand thatVe=Vgonly at each peak of transmission(|t|2=1).This result impacts our understanding of the effective dispersion properties of layered materials, and can be used to better understand a wide range of phenomena including the question of superluminal tunneling times. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372732

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Second-order nonlinear optical processes in spatially modulated material structures are investigated. In a first part, second harmonic generation in photonic crystals is considered, experimentally and theoretically, in two cases: first, when the nonlinear material is located within a “defect” in a single-dimensional periodic structure; and, second, when the nonlinear material is distributed all along a regular three-dimensional structure. It is also shown in this part that for narrow layers of second-order nonlinear material “momentum non-conserving” interactions can be as important as momentum conserving interactions. Finally, in a second part it is investigated how, in a microcavity, cascading effects induced by an intense second harmonic field can modify the reflectance properties of the structure at the fundamental frequency (nonlinear reflection). ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1372733

出版商:AIP    

年代:1901

数据来源: AIP