scholarly journals Nanocrystal Quantum Dots: Building Blocks for Tunable Optical Amplifiers and Lasers

2001 ◽  
Vol 667 ◽  
Author(s):  
Jennifer A. Hollingsworth ◽  
Alexander A. Mikhailovsky ◽  
Anton Malko ◽  
Victor I. Klimov ◽  
Catherine A. Leatherdale ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement ◽  
Optical Amplifiers ◽  
Optical Gain ◽  
Building Blocks ◽  
Stimulated Emission ◽  
Optical Amplification ◽  
Organometallic Reactions ◽  
Wide Range ◽  
Nanocrystal Quantum Dots

ABSTRACTWe study optical processes relevant to optical amplification and lasing in CdSe nanocrystal quantum dots (NQD). NQDs are freestanding nanoparticles prepared using solution-based organometallic reactions originally developed for the Cd chalcogenides, CdS, CdSe and CdTe [J. Am. Chem. Soc. 115, 8706 (1993)]. We investigate NQDs with diameters ranging from 2 to 8 nm. Due to strong quantum confinement, they exhibit size-dependent spectral tunability over an energy range as wide as several hundred meV. We observe a strong effect of the matrix/solvent on optical gain properties of CdSe NQDs. In most of the commonly used solvents (such as hexane and toluene), gain is suppressed due to strong photoinduced absorption associated with carriers trapped at solvent-related interface states. In contrast, matrix-free close packed NQD films (NQD solids) exhibit large optical gain with a magnitude that is sufficiently high for the optical gain to successfully compete with multiparticle Auger recombination [Science 287, 10117 (2000)]. These films exhibit narrowband stimulated emission at both cryogenic and room temperature, and the emission color is tunable with dot size [Science 290, 314 (2000)]. Moreover, the NQD films can be incorporated into microcavities of different geometries (micro-spheres, wires, tubes) that produce lasing in whispering gallery modes. The facile preparation, chemical flexibility and wide-range spectral tunability due to strong quantum confinement are the key advantages that should motivate research into NQD applications in optical amplifiers and lasers.

scholarly journals Amplified Spontaneous Emission and Optical Gain in Organic Single Crystal Quinquethiophene

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 609 ◽  
Author(s):  
Muhammad Zeb ◽  
Muhammad Tahir ◽  
Fida Muhammad ◽  
Suhana Mohd Said ◽  
Mohd Faizul Mohd Sabri ◽  
...  
Keyword(s):  
Single Crystal ◽  
Spontaneous Emission ◽  
Threshold Energy ◽  
Pump Energy ◽  
Optical Gain ◽  
Amplified Spontaneous Emission ◽  
Stimulated Emission ◽  
Excitation Wavelength ◽  
Optical Amplification ◽  
Organic Single Crystal

In this paper, we report optical characteristics of an organic single crystal oligomer 5,5⁗-diphenyl-2,2′:5′,2″:5″,2‴:5‴,2⁗-quinquethiophene (P5T). P5T crystal is a thiophene/phenylene co-oligomer that possesses better charge mobility as well as photoluminescence quantum efficiency (PLQE) as compared to other organic materials. Stimulated emission in P5T is investigated via amplified spontaneous emission (ASE) measurements within broad pump energies ranging from 35.26 to 163.34 µJ/cm2. An Nd-YAG femtosecond-tunable pulsed laser is used as a pump energy source for the ASE measurements of P5T crystals at an excitation wavelength of 445 nm. The ASE spectra exhibit optical amplification in P5T crystals at a 625 nm peak wavelength with a lower threshold energy density (Eth) ≈ 52.64 μJ/cm2. P5T also demonstrates higher optical gain with a value of 72 cm−1, that is calculated by using the variable stripe-length method. The value of PLQE is measured to be 68.24% for P5T. This study proposes potential applications of P5T single crystals in organic solid state lasers, photodetectors, and optical amplifiers.

scholarly journals Optical gain from InAs nanocrystal quantum dots in a polymer matrix

2005 ◽  
Vol 87 (25) ◽  
pp. 251108 ◽  
Author(s):  
Gang Chen ◽  
Ronen Rapaport ◽  
Dan T. Fuchs ◽  
Leah Lucas ◽  
Andrew J. Lovinger ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Polymer Matrix ◽  
Optical Gain ◽  
Nanocrystal Quantum Dots

Applied to anti-counterfeiting and flexible composite utilizing photoluminescence properties of CdSe/ZnS nanocrystal quantum dots via hot-injection

2021 ◽  
Vol 11 (9) ◽  
pp. 1554-1560
Author(s):  
Jae Yong Jung ◽  
Soung Soo Yi
Keyword(s):  
Quantum Dots ◽  
Uv Light ◽  
Quantum Confinement Effect ◽  
Bright Light ◽  
Bank Note ◽  
Wide Range ◽  
Hot Injection ◽  
Nanocrystal Quantum Dots ◽  
Bio Imaging ◽  
Silicon Based

Quantum dots with excellent luminescence properties are being studied in a wide range of fields, such as displays, sunlight, and bio-imaging; although quantum dots are the same material, unlike bulk materials, as their size decreases their optical and electrical properties change due to the quantum confinement effect. In this study, CdSe quantum dots were synthesized by a well-known hot-injection method and a ZnS shell layer was formed on the surface of the CdSe quantum dot core to enhance the properties, thereby synthesizing the CdSe/ZnS core/shell structure. At this time, the quantum yield increased more than twice, and the emission line width decreased. When anti-counterfeiting ink was made using quantum dots with enhanced luminescence characteristics and applied to a bank note, it was impossible to check with the naked eye, but letters and emblems could be confirmed under UV light. In addition, a composite made by mixing with a silicon-based polymer showed excellent flexibility; and, when applied on a blue LED chip, a single wavelength and bright light peculiar to quantum dots were realized.

Optical Gain in Foerster Energy Transfer Based Organic Guest-Host-Systems

2009 ◽  
Vol 1197 ◽  
Author(s):  
Torsten Rabe ◽  
Sebastian Döring ◽  
Niko Hildebrandt ◽  
Thomas Riedl ◽  
Wolfgang Kowalsky ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Emission Cross Section ◽  
Pump Energy ◽  
Optical Gain ◽  
Stimulated Emission ◽  
Wide Range ◽  
Förster Energy Transfer ◽  
Donor Acceptor ◽  
Stimulated Emission Cross Section

AbstractWe study the optical gain for various doping concentrations in a dye doped polymer (poly-[9,9-dioctylfluorene] with 6,6'-[2,2'-octyloxy-1,1'-binaphthyl] spacer groups (BN-PFO) doped by the stilbene dye 1,4-bis[2-[4-[N,N-di[p-tolyl]amino]phenyl]vinyl-benzene] (DPAVB)). In such a guest-host-system (GHS) the occupation of the upper laser level (dopant site) is due to Förster energy transfer (FET), which strongly depends on the donor acceptor distance and hence on the concentration of the laser dye. Therefore, the doping concentration is varied over a wide range and the gain coefficients are measured at various excitation densities to analyze the stimulated emission cross section.For the investigated GHS maximum gain coefficients up to ∼340 1/cm were found at absorbed pump energy densities of around 50 μJ/cm2. It will be shown that the stimulated emission cross section (σ = 1.8 × 10−16 cm2) is concentration independent which is quite different to a recently investigated small molecule based GHS. These effects will be discussed considering the rate and exciton diffusion constants.

Quantum efficiency of stimulated emission in colloidal semiconductor nanocrystal quantum dots

2009 ◽  
Vol 80 (3) ◽  
Author(s):  
Chunfeng Zhang ◽  
Jian Xu ◽  
Ting Zhu ◽  
Fan Zhang ◽  
Zhanao Tan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Efficiency ◽  
Stimulated Emission ◽  
Semiconductor Nanocrystal ◽  
Nanocrystal Quantum Dots ◽  
Colloidal Semiconductor

scholarly journals Nanocrystals and Quantum Dots Formed by High-Dose Ion Implantation

1995 ◽  
Vol 396 ◽  
Author(s):  
C.W. White ◽  
J. D. Budai ◽  
J. G. Zhu ◽  
S. P. Withrow ◽  
D. M. Hembree ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ion Implantation ◽  
Thermal Annealing ◽  
Quantum Confinement ◽  
Compound Semiconductors ◽  
High Dose ◽  
Confinement Effects ◽  
Quantum Confinement Effects ◽  
Wide Range ◽  
Elemental Semiconductors

AbstractIon implantation and thermal annealing have been used to produce a wide range of nanocrystals and quantum dots in amorphous (SiO2) and crystalline (AI2O3) matrices. Nanocrystals of metals (Au), elemental semiconductors (Si and Ge), and even compound semiconductors (SiGe, CdSe, CdS) have been produced. In amophous matrices, the nanocrystals are randomly oriented, but in crystalline matrices they are three dimensionally aligned. Evidence for photoluminescence and quantum confinement effects are presented.

Optical Amplification In Nanocrystalline Silicon Superlattices

2002 ◽  
Vol 737 ◽  
Author(s):  
J. Ruan ◽  
H. Chen ◽  
Philippe M. Fauchet
Keyword(s):  
Amorphous Silicon ◽  
Silicon Layer ◽  
Optical Gain ◽  
Nanocrystalline Silicon ◽  
Computing System ◽  
Stimulated Emission ◽  
Optical Amplification ◽  
Si Nanocrystals ◽  
Overall Performance ◽  
Cladding Layers

ABSTRACTToday, the overall performance of a multi-chip computing system is limited by the interconnection delay between chips. Conventional interconnects based on metal lines are expected to cause unmanageable problems with speed and power dissipation. Optical interconnects provide a solution to these problems. However, the low quantum efficiency associated with radiative recombination in silicon has so far prevented the demonstration of a practical laser. Recently stimulated emission has been demonstrated in Si nanocrystals prepared by ion-implantation. The reported material gain is high enough to realize a practical Si based laser. However, the optical filling factor in these samples was less than 10% due to the poor wave guiding nature of these structures.In this work, we explore a possible way to achieve optical gain in nanocrystalline silicon superlattices. The samples are produced by growing alternating layers of amorphous silicon and SiO2 and then using a two step crystallization method to transform each amorphous silicon layer into a high density array of silicon nanocrystals having identical size. The waveguide structure is formed by sandwiching the superlattice between cladding layers. To measure optical gain we use the variable stripe length method where the amplified spontaneous emission emitted from the edge is measured as a function of the excitation length. Tuning from loss to gain was observed by just varying the pump power.

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