Production of nanostructures consisting of semiconductor nanoparticles (NPs) is of interest for number of applications. Development of new methods of NPs' manipulation and aggregation of NPs into nanostructures with pre-defined geometry is also of considerable interest from the fundamental point of view. Under laser irradiation with properly chosen wavelengths excitonic excitations of semiconductor NPs will be induced. Electrodynamical interaction between excited NPs is rather universal and allows formation of wide variety of nanostructures both of homo- and heterogeneous content. Theoretical approach for study of interaction of NPs' ensembles with laser light includes dipole-dipole approximation for NPs' attraction. Experimental results are obtained for TGA stabilized CdTe QDs with the excitonic resonance at 520 nm. Six different samples of the same colloid solution were irradiated at wavelengths from 540 to 570 nm. Modifications of absorption spectra of solutions after irradiation was detected, being most prominent at 555 and 560 nm irradiation wavelengths. Analysis of spectra shows that up to 47% of QDs were assembled into pairs with 10 nm inter-QD distance. Therefore, possibility of precise QDs manipulation via laser-induced electrodynamical interaction is demonstrated.
The properties of NPC structures in strontium tetraborate are analyzed. Different types of NPC structures are revealed
that possess different nonlinear properties, and their spectral dependences of frequency conversion efficiency are
calculated and compared. Experimental study of these structures is reported for the process of doubling of the second
harmonic of fs Ti:S laser. Tuning of generated radiation is obtained in the range 187.5 - 232.5 nm, with extreme
insensitivity to the angular orientation of NPC. Behavior of tuning curve along investigated fundamental wave range is
similar in all studied samples, but efficiency obtained depends on the type of structure. Conversion efficiency and
spectral quality of generated radiation is experimentally shown to grow better when using NPC with improved structure.
Prospects of VUV converter on a single NPC are discussed. NPCs of SBO are demonstrated to be useful for
autocorrelation diagnostics both in random QPM geometry and in the geometry of nonlinear diffraction from virtual
beam.
Random quasi-phase-matched frequency doubling of fs pulses to the deep UV was obtained in 1D nonlinear photonic
crystal (NPC) of strontium tetraborate. Tuning range of generated radiation is from 187.5 to 215 nm. The spectrum of
generated radiation consists from series of peaks with the width of order of 1 Å. These peaks are the manifestation of the
NPC band structure. Using fs oscillator as the fundamental radiation source, maximum average power of generated
radiation is of order 1 μW, the enhancement factor with respect to monodomain sample being of order of several
hundred. The red rotational shift of NPC band structure is experimentally demonstrated.
Random nonlinear photonic crystal (NPC) structures formed by as-grown domains in a non-ferroelectric strontium
tetraborate (SBO) are investigated. The domain shape and orientation are similar to those in ferroelectric KTP. Nonlinear
diffraction is the simplest way to detect, evaluate and characterize these structures. Reciprocal superlattice vectors
spectra of NPC in SBO are very wide and enable broadband efficiency enhancement of nonlinear optical processes.
Second harmonic (SH) generation of femtosecond Ti:sapphire oscillator radiation with 1.9% efficiency is obtained using
nonlinear diffraction geometry. Random quasi phase matched generation at the wavelengths of fourth harmonic of
Ti:sapphire laser is obtained with average power up to 1μW.
Spontaneously grown partially ordered domain structures in SBO crystals are characterized via nonlinear
diffraction. Domains have the form of sheets lying in cb plane with the domain walls oriented perpendicularly to the a
crystallographic axis. The thickness of domains varies in quite wide range. The effective thickness of domains
contributing to the nonlinear diffraction is determined from Fourier spectrum of inverse superlattice wave vectors to lie
between 180 nm and 8 microns. General properties of spatial Fourier spectrum are reproducible from one growth
procedure to another, however, details of spectrum noticeably vary. Enhancement factors for random QPM are calculated
and found to be of order of several thousand in the near UV.
Partially ordered domain structure is detected for the first time in non-ferroelectric strontium tetraborate crystal
via nonlinear diffraction. Domains have the form of sheets with the domain walls oriented perpendicularly to the α
crystallographic axis. The thickness of domains is the random quantity; the spatial Fourier spectrum of the nonlinear
susceptibility protrudes from π/6 to π/0.2 μm-1.
The ablation with XeCl laser is used for the deposition of europium borate glass thin films. Optical spectra of these films show no indications of the presence of trivalent europium, contrary to the material of the target. UV absorption spectra of the films Magneto-optical activity of the deposited films is demonstrated with the help of magnetic circular dichroism spectra in the spectral range 320 - 450 nm.
A possibility is considered of obtaining photoelectron spectra of solid state samples near the Fermi edge at an energy resolution down to 1 meV and moderate spectra accumulation times with the help of a time-of-flight analyzer combined with a specially designed UV laser source. Limitations of count rate for such a device and their influence on the energy resolution are considered. The requirements to the laser sources including their wavelengths, pulse duration, repetition rate and pulse energies are discussed. Several possibilities are considered to build the necessary laser source, basing on excimer laser and nonlinear-optically converted neodymium-doped, argon and dye lasers. The construction of required source is shown to be quite feasible.
KEYWORDS: laser, photoemission, time-of-flight electron energy analyzer, superconductivity.
Dynamic orientation of anisotropic molecules in a gas-phase medium under the action of laser pulses of a duration shorter than the rotation relaxation time has been studied both theoretically and experimentally. The effect was observed in the VUV third-harmonic generation in naphthalene vapor. The peculiarities of nonlinear optical UV and VUV generation (by frequency mixing of Nd-laser radiation) in the vapors of some compounds are studied.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.