Ultrafast photoresponse of a structured YBa/sub 2/Cu/sub 3/O/sub 7- delta / thin film to ultrashort FIR laser pulses

1993 ◽  
Vol 3 (1) ◽  
pp. 2160-2162 ◽  
Author(s):  
R.S. Nebosis ◽  
M.A. Heusinger ◽  
W. Schatz ◽  
K.F. Renk ◽  
G.N. Gol'tsman ◽  
...  
Keyword(s):  
Thin Film ◽  
Laser Pulses ◽  
Fir Laser

GENERATION OF ULTRASHORT ELECTRON BUNCHES IN NANOSTRUCTURES BY FEMTOSECOND LASER PULSES

2007 ◽  
Vol 17 (03) ◽  
pp. 571-576
Author(s):  
A. GLADUN ◽  
V. LEIMAN ◽  
A. ARSENIN ◽  
O. MANNOUN ◽  
V. TARAKANOV
Keyword(s):  
Thin Film ◽  
Laser Radiation ◽  
Femtosecond Laser ◽  
Electric Field ◽  
Surface Plasmon ◽  
Laser Pulses ◽  
Photoelectric Effect ◽  
Femtosecond Laser Pulses ◽  
Electron Bunches ◽  
Internal Photoelectric Effect

We present numerical investigation of anomalous internal photoelectric effect which is realized in thin film (< 100 nm) structures by surface plasmon (SP) excitation and its interaction with primary laser radiation. SP electric field gain and electron temperature in the SP field have been calculated.

scholarly journals All-optical dynamic tuning of local excitonic emission of monolayer MoS2 by integration with Ge2Sb2Te5

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2351-2359
Author(s):  
Hao Ouyang ◽  
Haitao Chen ◽  
Yuxiang Tang ◽  
Jun Zhang ◽  
Chenxi Zhang ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Optical Networks ◽  
Dominant Role ◽  
Laser Pulses ◽  
Coulomb Interactions ◽  
Optical Modulators ◽  
Dynamic Tuning ◽  
All Optical ◽  
Excitonic Emission

AbstractStrong quantum confinement and coulomb interactions induce tightly bound quasiparticles such as excitons and trions in an atomically thin layer of transitional metal dichalcogenides (TMDs), which play a dominant role in determining their intriguing optoelectronic properties. Thus, controlling the excitonic properties is essential for the applications of TMD-based devices. Here, we demonstrate the all-optical tuning of the local excitonic emission from a monolayer MoS2 hybridized with phase-change material Ge2Sb2Te5 (GST) thin film. By applying pulsed laser with different power on the MoS2/GST heterostructure, the peak energies of the excitonic emission of MoS2 can be tuned up to 40 meV, and the exciton/trion intensity ratio can be tuned by at least one order of magnitude. Raman spectra and transient pump-probe measurements show that the tunability originated from the laser-induced phase change of the GST thin film with charge transferring from GST to the monolayer MoS2. The dynamic tuning of the excitonic emission was all done with localized laser pulses and could be scaled readily, which pave a new way of controlling the excitonic emission in TMDs. Our findings could be potentially used as all-optical modulators or switches in future optical networks.

scholarly journals Characteristics of Coherent Optical Phonons in a Hexagonal YMnO3 Thin Film

2019 ◽  
Vol 9 (4) ◽  
pp. 704 ◽  
Author(s):  
Takayuki Hasegawa
Keyword(s):  
Thin Film ◽  
Optical Phonon ◽  
Laser Pulses ◽  
Generation Process ◽  
Neel Temperature ◽  
Optical Phonons ◽  
Néel Temperature ◽  
Temperature Range ◽  
Lower Temperature Range ◽  
Lower Temperature

This paper reviews our recent study on a coherent optical phonon in a hexagonal YMnO3 thin film together with related optical studies in hexagonal RMnO3 (R = Y, Lu, Ho) compounds. Coherent phonons have been observed in RMnO3 compounds by pump-probe spectroscopy with subpicosecond laser pulses, whereas the observation of coherent optical phonons was reported only in LuMnO3. Recently, we succeeded in the observation of the coherent optical phonon in a YMnO3 thin film. The generation process of the coherent optical phonon is assigned to a displacive mechanism, which is identical to that in LuMnO3. The coherent optical phonon is observed in the temperature range from 10 K to room temperature, while the oscillation intensity strongly decreases as the temperature increases to the Néel temperature of ~70 K from a lower temperature range. It is interesting that the temperature dependence is largely different from that in LuMnO3. We describe that the result can be qualitatively explained by the property of an isostructural transition around the Néel temperature in RMnO3 compounds. In addition, we briefly discuss ultrafast incoherent responses of excited electronic states from the viewpoint of the excitation photon energy of laser pulses.

Demonstration of thin film compression for short-pulse X-ray generation

2019 ◽  
Vol 34 (34) ◽  
pp. 1943015
Author(s):  
D. M. Farinella ◽  
M. Stanfield ◽  
N. Beier ◽  
T. Nguyen ◽  
S. Hakimi ◽  
...  
Keyword(s):  
Thin Film ◽  
Imaging System ◽  
Short Pulse ◽  
Laser Pulses ◽  
Single Cycle ◽  
X Ray ◽  
Ultrafast Laser Pulses ◽  
Solid Density ◽  
Fs Laser ◽  
Gaussian Mode

Thin film compression to the single-cycle regime combined with relativistic compression offers a method to transform conventional ultrafast laser pulses into attosecond X-ray laser pulses. These attosecond X-ray laser pulses are required to drive wakefields in solid density materials which can provide acceleration gradients of up to TeV/cm. Here we demonstrate a nearly 99% energy efficient compression of a 6.63 mJ, 39 fs laser pulse with a Gaussian mode to 20 fs in a single stage. Further, it is shown that as a result of Kerr-lensing, the focal spot of the system is slightly shifted on-axis and can be recovered by translating the imaging system to the new focal plane. This implies that with the help of wave-front shaping optics the focusability of laser pulses compressed in this way can be partially preserved.

Poly-Resistor Thin Film Formation by Excimer Laser Micromachine

2015 ◽  
Vol 780 ◽  
pp. 17-21
Author(s):  
A.F.M. Anuar ◽  
Yufridin Wahab ◽  
M.Z. Zainol ◽  
H. Fazmir ◽  
M. Najmi ◽  
...  
Keyword(s):  
Thin Film ◽  
Excimer Laser ◽  
Laser Energy ◽  
Film Formation ◽  
Chemical Vapor ◽  
Laser Pulses ◽  
Beam Size ◽  
Silicon Thin Film ◽  
Pressure Chemical ◽  
Krf Excimer Laser

A simple theoretical model and resistor fabrication for calculating the resistance of a polycrystalline silicon thin film is presented. The resistance value for poly-resistor is perfomed in terms of polysilicon thickness and its total area. The KrF excimer laser micromachine is used in assisting the resistor formation for a low pressure chemical vapor deposition (LPCVD) based polysilicon. Laser micromachine with three main parameters is used to aid the fabrication of the poly-resistor; namely as the pulse rate (i.e. number of laser pulses per second), laser beam size and laser energy. These parameters have been investigated to create the isolation between materials and also to achieve the desired poly-resistor shape. Preliminary results show that the 35 um beam size and 15 mJ of energy level is the most effective parameter to produce the pattern. Poly-resistor formation with 12 and 21 number of squares shows the total average resistance of 303.52 Ω and 210.14 Ω respectively. The laser micromachine process also significantly reduce the total time and number of process steps that are required for resistor fabrication.

Structural and Morphological of Pulsed Laser Deposited Magnesium Phthalocyanine (MgPc) Thin Film

2020 ◽  
Vol 29 ◽  
pp. 15-21
Author(s):  
Noor M. Ibrahim ◽  
Eman K. Hassan
Keyword(s):  
Thin Film ◽  
Surface Morphology ◽  
Structural Characteristics ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
X Ray Diffraction ◽  
Characteristic Peak ◽  
Monoclinic Form ◽  
Optimum Parameters ◽  
Diffraction Peaks

Magnesium Phthalocyanine (MgPc) was deposited on a glass substrate by pulsed laser deposition (PLD) using Q-Switching Nd: YAG laser with wavelength 1064(nm), (6Hz) Repetition rate, in addition to different laser energies (200,300,400 and 500 mJ) at room temperature under vacuum condition with (10-3torr). All films were annealed at (298K) for 1hour to attain crystallinity. X-ray diffraction of MgPc powder indicated the fact that MgPc crystallizes in polycrystalline with a monoclinic structure While comparing the MgPc of films, it’s found the intensity of characteristic peak is high as the number and energy of laser pulses increase and the crystallize is monoclinic form is observed in β-form. Miller indices, hkl, values for every one of the diffraction peaks in the spectrum of the XRD have been computed. The characteristic peak of Phthalocyanine (MgPc) is found at 2θ value 6.9137o with the hkl value of {100} for both MgPc powder and deposited thin film. The surface morphology of the films showed more uniform sized grains. EDX and FESEM analysis has shown that there has been an enhancement in the crystallinity and surface morphology as a result of the increase of laser energies and for finding the optimum parameters for which film provides more efficient structural characteristics.

Transient Reflectance Response to Hot Electron Relaxation in InP Based Films

2002 ◽  
Author(s):  
J. Michael Klopf ◽  
John L. Hostetler ◽  
Pamela M. Norris
Keyword(s):  
Thin Film ◽  
Transient Absorption ◽  
Film Growth ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Photon Absorption ◽  
Hot Electron ◽  
Carrier Relaxation ◽  
Hot Carrier ◽  
Ultrashort Laser

Advancements in technologies related to thin film growth have led to astoundingly complex integrated photonic devices. The reliability of these devices relies upon the precise control of the band gap and absorption mechanisms in the thin film structures. Photon absorption in these devices can result in a reduction of laser efficiency as well as thermal runaway. To improve device performance prediction, an increased understanding of the localized absorption processes is paramount. A pump-probe technique is being developed to measure the transient absorption during hot carrier relaxation. This method relies upon the generation of hot carriers by the absorption of an intense ultrashort laser pulse. The change in reflectance due to hot carrier generation and relaxation is monitored using a probe pulse focused at the center of the excited region. The transient reflectance is measured as a function of the relative delay between the pump and probe pulses. Utilizing ultrashort laser pulses (τp ∼ 190 fs) it is possible to attain sub-picosecond resolution of the transient reflectance during hot carrier relaxation. Transient changes in the reflectance can then be related to transient changes in the absorption mechanisms of the film. Preliminary measurements made with this technique have shown clear differences in the transient reflectance of doped and undoped Indium Phosphide (InP) based films. This study will form the basis for development of a transient thermoreflectance model during hot carrier relaxation in III-V semiconductors.

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