Stimulated Emission and Laser Action from the Organic Ligand of Gadolinium Chelates

Nature ◽  
1968 ◽  
Vol 217 (5129) ◽  
pp. 631-633
Author(s):  
N. FILIPESCU ◽  
C. R. HURT ◽  
N. MCAVOY
Keyword(s):  
Organic Ligand ◽  
Laser Action ◽  
Stimulated Emission ◽  
Gadolinium Chelates

Stimulated emission of Ho3+ and Er3+ ions in Gd3Ga5O12 crystals and cascade laser action of Ho3+ ions over the5S2 →5I5 →5I6 →5I8 scheme

1979 ◽  
Vol 53 (2) ◽  
pp. K219-K222 ◽  
Author(s):  
A. A. Kaminskii ◽  
V. A. Fedorov ◽  
S. E. Sarkisov ◽  
J. Bohm ◽  
P. Reiche ◽  
...  
Keyword(s):  
Laser Action ◽  
Stimulated Emission

VUV SPECTROSCOPY OF CRYSTALLINE EMITTERS BASED ON 5d–4f TRANSITIONS IN RARE EARTH IONS

2002 ◽  
Vol 09 (01) ◽  
pp. 621-626 ◽  
Author(s):  
V. N. MAKHOV ◽  
N. YU. KIRIKOVA ◽  
N. M. KHAIDUKOV ◽  
M. KIRM ◽  
E. NEGODIN ◽  
...  
Keyword(s):  
Stokes Shift ◽  
Laser Action ◽  
Spectroscopic Properties ◽  
Rare Earth Ions ◽  
Stimulated Emission ◽  
Solid State Lasers ◽  
Nonradiative Relaxation ◽  
Level Laser ◽  
Vuv Spectroscopy ◽  
Strong Spin

The spectroscopic properties of several fluoride crystals ( LiYF 4, KYF 4, K 2 YF 5, KLiYF 5, CsY 2 F 7, SrF 2) doped with Nd 3+, Er 3+ or Tm 3+ are analyzed from the viewpoint of their possible applications as active media for VUV solid state lasers. It has been found that in many crystals there exists very efficient nonradiative relaxation from higher-lying 5d states to the lowest 5d level responsible for the spin-forbidden luminescence. In fact, the energy level diagram of 5d–4f transitions for these two ions represents a typical four-level laser scheme with a considerably larger Stokes shift of 5d–4f luminescence from the edge of the strong spin-allowed 4f–5d absorption than for Nd 3+, which causes smaller reabsorption of emitted VUV radiation in the crystals doped with Er 3+ or Tm 3+. Two crystals LiYF 4: Nd 3+ and SrF 2: Er 3+ were tested for laser action under pumping by a pulsed F 2 laser operating at 157 nm. However, no indications of the appearance of stimulated emission have been detected for both crystals. The possible reasons for the absence of lasing are discussed.

Laser action of two conjugated polymers in solution and in solid matrix: The effect of aggregates on spontaneous and stimulated emission

2002 ◽  
Vol 65 (19) ◽  
Author(s):  
M. Fakis ◽  
I. Polyzos ◽  
G. Tsigaridas ◽  
V. Giannetas ◽  
P. Persephonis ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Laser Action ◽  
Stimulated Emission ◽  
Solid Matrix

Entropy and Efficiency in Laser Cooling of Solids

2007 ◽  
Author(s):  
Xiulin Ruan ◽  
Stephen C. Rand ◽  
Massoud Kaviany
Keyword(s):  
Laser Cooling ◽  
Laser Action ◽  
Blackbody Radiation ◽  
Stimulated Emission ◽  
Light Sources ◽  
Photon Distribution ◽  
Random Lasers ◽  
Emission Process ◽  
Wide Range ◽  
Radiation Entropy

The thermodynamics of laser cooling of solids is analyzed. Using the general theory of radiation entropy, the important roles of the optical frequency and the photon distribution function in determining the radiation entropy are identified. The usefulness of a narrowband approximation is established for a wide range of radiant sources. This approximation is then applied to compare the entropies of different light sources, including blackbody radiation, lasers, fluorescence, and the emerging class of random lasers. Based on these results, the Carnot efficiency for laser cooling of solids is determined, for emission fields with various entropy characteristics. It is shown that fluorescent emission is the most efficient form of the radiated field for laser cooling of solids, and cooling schemes based on any stimulated emission process (including random laser action) are inherently less efficient. The influence of luminescence quantum yield on cooling is also considered.

Ultrafast All-optical Switching and Laser Action in Rotaxane

2009 ◽  
Vol 1230 ◽  
Author(s):  
Marta M. Mroz ◽  
Stefano Perissinotto ◽  
Tersilla Virgili ◽  
Marco Salerno ◽  
Giuseppe Sforazzini ◽  
...  
Keyword(s):  
Optical Switching ◽  
Laser Action ◽  
Stimulated Emission ◽  
Visible Range ◽  
Relaxation Processes ◽  
Optical Logic ◽  
Neat Polymer ◽  
All Optical ◽  
Non Linear ◽  
Chain Interaction

AbstractLinear and non-linear optical properties of conjugated polymers are often masked by the inter-chain network in solid state. The formation of aggregates may trap excitons, reduce oscillator strength and modify relaxation processes. The control of the inter-chain interaction is the main reason for developing “threaded” polymers, where supra-molecular encapsulation should reduce aggregation. Here, we investigate the influence of the encapsulation with β-cyclodextrin (β-CD) macrocycles on the photophysics of the polyfluorene-alt-biphenylene (PFBP) using femtosecond non-linear spectroscopy. Upon threading we observe enhancement of the stimulated emission (SE) in the visible range and reduction of the charge absorption. These phenomena are ascribed to the reduced inter-chain interaction. In more isolated chains the dynamics of intra and inter-chain charge states are distinguished. In addition, we performed three-beam experiments in which a first pulse (pump) creates singlet excited states; a second (push) pulse re-excite the singlet state and a broadband probe pulse detects the induced changes in transmission. This technique shows: (i) charges are generated from higher lying singlet states also in isolated chains (ii) ultrafast optical gain switching is possible in threaded chain. Finally, we demonstrate that ASE occurs in films of threaded polymers and lasing can be achieved with much lower threshold than the neat polymer chain in the DFB configuration. All our findings point out the potential role of rotaxanes in photonics, as amplifiers and reopen the route to the electrically pumped organic lasers and all-optical logic devices.

scholarly journals ‘Social Laser’: action amplification by stimulated emission of social energy

2016 ◽  
Vol 374 (2058) ◽  
pp. 20150094 ◽  
Author(s):  
Andrei Khrennikov
Keyword(s):  
Laser Action ◽  
Social Processes ◽  
Stimulated Emission ◽  
Political Literature ◽  
Novel Approach ◽  
The Social ◽  
The Usa ◽  
Laser Model ◽  
The Moment ◽  
Acceptable Theory

The problem of the ‘explanation’ of recent social explosions, especially in the Middle East, but also in Southern Europe and the USA, has been debated actively in the social and political literature. We can mention the contributions of P. Mason, F. Fukuyama, E. Schmidt, J. Cohen and I. Krastev to this debate. We point out that the diversity of opinions and conclusions is really amazing. At the moment, there is no consistent and commonly acceptable theory of these phenomena. We present a model of social explosions based on a novel approach for the description of social processes, namely the quantum-like approach. Here quantum theory is treated simply as an operational formalism—without any direct relation to physics. We explore the quantum-like laser model to describe the possibility of action amplification by stimulated emission of social energy.

Stimulated Emission and Laser Action in Gallium Nitride

1971 ◽  
Vol 19 (1) ◽  
pp. 5-7 ◽  
Author(s):  
R. Dingle ◽  
K. L. Shaklee ◽  
R. F. Leheny ◽  
R. B. Zetterstrom
Keyword(s):  
Gallium Nitride ◽  
Laser Action ◽  
Stimulated Emission

Fabrication and Properties of AlGaN/GaInN Double Heterostructure Grown on 6H-SiC(0001)Si

1995 ◽  
Vol 395 ◽  
Author(s):  
Hiroshi Amano ◽  
Shigetoshi Sota ◽  
Masaki Nishikawa ◽  
Masato Yoshida ◽  
Makoto Kawaguchi ◽  
...  
Keyword(s):  
Power Efficiency ◽  
Room Temperature ◽  
Optical Pumping ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Laser Action ◽  
Stimulated Emission ◽  
Threshold Power ◽  
Light Emitting ◽  
Double Heterostructures

ABSTRACTAlGaN/GalnN double heterostructures (DH) were fabricated by metalorganic vapor phase epitaxy on the (0001)Si 6H-SiC substrate. A cleaved edge shows a very flat surface with roughness on the order of one monolayer. Stimulated emission and laser action from the UV to blue region was observed by optical pumping at room temperature (RT). The threshold power density was 27KW/cm2 which is smaller than that of the same structure grown on a sapphire (0001) substrate by a factor of four. A AlGaN/GalnN DH UV light emitting diode, using undoped GalnN is fabricated. The power efficiency and spectra width of this LED is comparable or superior to that of an LED having the same structure but grown on sapphire.

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