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1.
Grazing-angle scattering (GAS) is a type of Bragg scattering in slanted wide periodic gratings. It occurs when the diffracted
order satisfying the Bragg condition (scattered wave) propagates at a grazing angle to the grating boundaries. Previous research
has been concerned only with first-order GAS, which has been shown to be a highly unusual type of scattering characterised
by a strong resonant increase of amplitudes of the scattered and incident waves in the grating. In this paper, a rigorous
numerical study of second-order GAS is presented for the case of bulk TE electromagnetic waves in planar holographic gratings.
A highly unusual pattern of strong resonances in the grating, which is strongly different from that for first-order GAS, is
predicted, described, and discussed. Physical interpretations of the predicted results are presented. In particular, a special
new type of eigenmodes in a slanted wide periodic grating with large amplitude is predicted. These eigenmodes are shown to
be guided by the grating alone without any conventional guiding effect in the structure. The typical field structure in such
eigenmodes is investigated and discussed.
Received: 16 September 2002 / Revised version: 4 November 2002 / Published online: 22 January 2003
RID="*"
ID="*"Corresponding author. Fax: +61-7/3864-9079, E-mail: d.pile@osa.org 相似文献
2.
Extremely asymmetrical scattering (EAS) is a type of Bragg scattering in periodic gratings, that occurs when the diffracted order satisfying the Bragg condition (scattered wave) propagates parallel to the grating boundaries. Previous studies were concerned only with first-order EAS that was shown to be a highly unusual type of scattering, characterised by a strong resonant increase of the scattered wave amplitude (i.e. the amplitude of the first diffracted order). In this paper, a rigorous numerical study of higher-order EAS is presented for the case of bulk TE electromagnetic waves in planar holographic gratings of various amplitudes and widths. In particular, it is demonstrated that typical scattered wave amplitudes in higher-order EAS are significantly smaller than those in first-order EAS, and display strongly different dependencies on grating width, grating amplitude, distance from the front grating boundary, etc. Similar to first-order EAS, second-order EAS is shown to be strongly sensitive to small variations of mean structural parameters at the grating boundaries. EAS in non-sinusoidal gratings is investigated in detail with special focus on the transition between first-order EAS and second-order EAS in such gratings. Tolerance of second-order EAS to the presence of the second grating harmonic is analysed. The effect of phase of the second grating harmonic on transitional EAS is investigated. Physical explanation of the predicted effects is presented. 相似文献
3.
E. Majkova S. Luby R. Senderak Y. Chushkin M. Jergel I. Zergioti D. Papazoglou A. Manousaki C. Fotakis 《Applied Physics A: Materials Science & Processing》2003,76(5):763-766
The sub-picosecond laser microstructuring of multilayer gratings is presented in this paper. A micromachining system operating
with a 0.5 ps KrF laser at 248 nm was used to etch grating structures with a groove width of 1–2 μm in Mo/Si and Si/Mo multilayers.
Atomic force microscopy, scanning electron microscopy and X-ray reflectivity were used to characterize the microetched patterns.
The ω-scans around the 1st Bragg maximum show symmetric satellites up to 3rd order, with positions corresponding to the grating
period. The use of sub-picosecond laser pulses minimizes the thermally affected zone and enhances the quality of the etched
features. Short pulse laser processing is advantageous for the fabrication of high spatial resolution microstructures required
in X-ray optics.
Received: 21 May 2002 / Accepted: 19 August 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Email: dpapa@iesl.forth.gr 相似文献
4.
J. Ihlemann S. Müller S. Puschmann D. Schäfer M. Wei J. Li P.R. Herman 《Applied Physics A: Materials Science & Processing》2003,76(5):751-753
Submicron surface-relief gratings were fabricated on fused silica by F2-laser ablation with nanosecond duration pulses from a high-resolution 157-nm optical processing system. A 157 nm wavelength
projection mask was prepared by ArF-laser ablation to form a 20-μm period grating of equal lines and spaces. A 25-fold demagnification
of the mask by a Schwarzschild objective generated gratings of an 830-nm period and a 250 nm modulation depth, as characterized
by SEM, AFM and HeNe-laser beam diffraction.
Received: 24 April 2002 / Accepted: 25 April 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +49-551/503 599, E-mail: jihle@llg.gwdg.de 相似文献
5.
Fabrication of planar gratings by direct ablation using an ultrashort pulse laser in a common optical path configuration 总被引:4,自引:0,他引:4
K. Venkatakrishnan N.R. Sivakumar B. Tan 《Applied Physics A: Materials Science & Processing》2003,76(2):143-146
Planar gratings have wide applications and to date, many methods for the fabrication of gratings have been reported. Ultrashort
pulse lasers have been used for the machining of gratings primarily because they allow direct ablation and the manufacturing
of sub-wavelength structures. In this paper, we present a novel direct ablation technique for the fabrication of planar gratings
which makes use of the interference of ultrashort pulses in a common optical path configuration. This technique of grating
fabrication not only simplifies the optical setup, but also immunizes the system to extraneous and inherent vibrations, thus
enabling the manufacturing of planar gratings of good edge acuity. We have successfully fabricated planar gratings on a copper
substrate.
Received: 6 November 2001 / Accepted: 4 March 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +65/77-904-674, E-mail: mvenkata@ntu.edu.sg 相似文献
6.
Second-order extremely asymmetrical scattering (EAS) and grazing-angle scattering (GAS) are types of Bragg scattering in slanted wide periodic gratings. They occur when the second diffracted order satisfies the Bragg condition and has a wavevector parallel (for EAS) and almost parallel (for GAS) to the grating boundaries. In this paper, for the first time, a rigorous numerical study of the frequency responses of second-order EAS and GAS is presented for bulk TE electromagnetic waves in planar holographic gratings. A highly unusual pattern of strong optical resonances in the side-lobe structure of these frequency responses is predicted. A relationship between these resonances and the previously predicted GAS resonances (at zero detunings of the Bragg condition) is established and analysed. A special new type of eigenmodes in slanted wide periodic gratings with strong frequency detunings are predicted in the case of second-order EAS and GAS. The eigenmodes are shown to be guided by the grating alone without any conventional guiding effect in the structure. The typical field structure in such eigenmodes is investigated and discussed. PACS 42.25Fx; 42.79Dj; 42.40Eq 相似文献
7.
T. Omatsu Y. Ojima B.A. Thompson A. Minassian M.J. Damzen 《Applied physics. B, Lasers and optics》2002,75(4-5):493-495
The high phase-conjugate reflectivity of 150, by four-wave mixing in a diode-pumped Nd:YVO4, has been demonstrated. The phase-conjugate mirror was capable of correcting the phase aberration of a probe beam. The experimental
diffraction efficiency of the transmission gratings was 60.
Received: 8 April 2002 / Revised version: 10 June 2002 / Published online: 25 September 2002
RID="*"
ID="*"Corresponding author. Fax: +81/43-290-3490, E-mail: omatsu@image.tp.chiba-u.ac.jp 相似文献
8.
A. Thompson N. Nazhestkina A. Siahmakoun G. Duree N. Roesler 《Applied physics. B, Lasers and optics》2003,76(5):547-554
We present experimental investigations of electrical fixing techniques in Ce:SBN:60. The effect of crystal fatigue on the
diffraction efficiency of electrically fixed photorefractive gratings is studied. We observed that applying an ac field to
the crystal eliminated crystal fatigue and improved diffraction efficiency. A controllable diffraction efficiency of a photorefractive
grating is presented. A reproducible diffraction efficiency of up to 75% is obtained using a write-reveal grating technique
with high-voltage pulses of opposite polarity. We also show that the diffraction efficiency can be controlled by varying the
intensity of the writing beams incident to the crystal during the recording process. A method of determining the hysteresis
loop using the domain-fixing technique is proposed. The dependence of the diffraction efficiency on the direction of the applied
electric field while writing the hologram is studied. Our experiments show that, during writing, when the electric field is
applied opposite to the c axis the grating can be successfully revealed with both positive and negative dc voltages. However,
when the grating is written with a field parallel to the c axis, the grating can be revealed only with a field applied in
the opposite direction.
Received: 28 October 2002 / Revised version: 28 February 2003 / Published online: 14 May 2003
RID="*"
ID="*"Corresponding author. Fax: +1-812/872-6167, E-mail: azad.siahmakoun@rose-hulman.edu 相似文献
9.
The results of statistical simulation of the spatiotemporal structure of the multiply scattered component of lidar returns
by the Monte Carlo method are discussed for the case of monostatic sensing geometry. The spatial characteristics of the region
of the medium where occurs the last scattering of photon before arriving at the reciever. This region of the medium is called
the instantaneous brightness body of multiply scattered radiation. It is demonstrated that the instantaneous brightness body
of multiply scattered radiation that propagates toward the receiver may occupy a large volume that does not necessarily coincide
with the region of formation of the singly scattered component. The main factors influencing the spatial and brightness characteristics
of this volume source are established. The effect of scattering order on the spatiotemporal structure of lidar returns is
analyzed for the case of sensing of aerosol haze and advective and radiative fogs with optical thickness 2<τ<8.
Received: 2 August 2001 / Revised version: 7 January 2002 / Published online: 25 September 2002
RID="*"
ID="*"Corresponding author. Fax: +7-38/2225-8026, E-mail: belov@iao.ru 相似文献
10.
A compact, diode-based difference-frequency laser system combined with a photoacoustic detection scheme is presented for trace-gas
sensing. It features a broad, continuous tuning range (3.2–3.7 μm), a narrow line width (154 MHz), and room-temperature operation,
and thus allows numerous gas species to be measured both isolated and in mixtures of different gases. Several trace-gas species
of environmental interest were detected, and gas mixtures were analysed. The detection limits are in the low-ppmV range, e.g.
1.3 ppmV for methane, 1.8 ppmV for ethane, and 1.2 ppmV for hydrogen chloride.
Received: 10 April 2002 / Revised version: 5 June 2002 / Published online: 12 September 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1077, E-mail: Sigrist@iqe.phys.ethz.ch 相似文献
11.
Crystal structure, morphology, depth profile of elements and mid-infrared optical constants of ‘mild’ lead telluride film 总被引:1,自引:0,他引:1
B. Li S. Zhang F. Zhang L. Zeng 《Applied Physics A: Materials Science & Processing》2003,76(6):965-968
The characterizations of a so-called ‘mild’ PbTe layer thermal-evaporated from an excess of Te (<1 mol.%) evaporable materials
are reported. The results reveal that the film obtained is polycrystalline and has a single-phase NaCl-type PbTe crystal structure.
It is also demonstrated that the film has a homogeneous surface morphology and a high degree of homogeneous distribution of
Te-rich components along the layer. The study of mid-infrared optical constants of a surface-polished film indicates that
the influence of surface scattering on optical properties is very small.
Received: 3 July 2002 / Accepted: 7 August 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86-21/6516-9946, E-mail: lbincome@yahoo.com 相似文献
12.
R. Frömter H.P. Oepen J. Kirschner 《Applied Physics A: Materials Science & Processing》2003,76(6):869-871
The basics of the scanning electron microscope with polarization analysis are briefly reviewed, emphasizing the achievable
magnetic resolution and image contrast. The design of an optimized spin-polarization detector based on the well-established
LEED scattering principle is presented. Results of first tests are reported.
Received: 2 September 2002 / Accepted: 2 September 2002 / Published online: 5 March 2003
RID="*"
ID="*"Corresponding author. Fax: +49-40/42838-6368, E-mail: RFroemte@PHYSnet.Uni-Hamburg.de 相似文献
13.
Photofabrication of periodic microstructures in azodye-doped polymers by interference of laser beams 总被引:4,自引:0,他引:4
Volume holographic gratings and two-dimensional periodic microstructures in azodye-doped polymethylmethacrylate were fabricated,
respectively, by interference of two coherent beams of a femtosecond laser and by interference of three coherent beams of
a nanosecond laser. The dependence of the first-order Bragg diffraction efficiency and the photoinduced refractive-index modulation
of the gratings on the intensity of the writing light was investigated. The measurements of the absorption spectra before
and after irradiation with the writing light suggest that the photoinduced gratings were refractive-index-modulated gratings,
which arose from a photoinduced decomposition reaction of the azodye molecules through multiphoton absorption. In the experiments
involving the interference of three beams, the period of the two-dimensional periodic microstructures was changed by adjusting
the angle between the three writing beams.
Received: 10 July 2002 / Revised version: 5 September 2002 / Published online: 20 December 2002
RID="*"
ID="*"Corresponding author. Fax: +81-774/955206, E-mail: jhsi@photon.jst.go.jp 相似文献
14.
Practical uses of femtosecond laser micro-materials processing 总被引:1,自引:0,他引:1
A. Zoubir L. Shah K. Richardson M. Richardson 《Applied Physics A: Materials Science & Processing》2003,77(2):311-315
We describe several approaches to basic femtosecond machining and materials processing that should lead to practical applications.
Included are results on high-throughput deep hole drilling in glasses in ambient air, and precision high-speed micron-scale
surface modification of composite materials and chalcogenide glasses. Ablation of soda-lime silicate glass and PbO lead-silicate
is studied under three different sets of exposure conditions, for which both the wavelength and pulse duration are varied.
Ablation rates are measured below and above the air ionization threshold. The differences observed are explained in terms
of self-channeling in the ablated hole. Fabrication of practical devices such as waveguides and gratings is demonstrated in
chalcogenide glass.
Received: 11 December 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +1-407/8233-570, E-mail: mrichard@mail.ucf.edu 相似文献
15.
We demonstrate, for the first time to our knowledge, operation of a self-adaptive holographic laser with wavelength selection,
which uses Nd:YLF as the gain medium. The holographic laser was self-starting and, by virtue of the temporal dynamics in writing
the gain grating, passively Q-switched the cavity to produce pulses with 20–50 ns duration. A pulse energy of 184 mJ was obtained
from the system with beams having a TEM00 spatial profile. Single-longitudinal-mode operation was observed with near-transform-limited bandwidth.
Received: 30 July 2002 / Revised version: 1 October 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +44-20/7594-7744, E-mail: s.y.lam@ic.ac.uk 相似文献
16.
S. Pereira J.E. Sipe M.A. Bader S. Soria G. Marowsky 《Applied physics. B, Lasers and optics》2002,75(6-7):635-640
We theoretically demonstrate the feasibility of using a grating-waveguide structure (GWS) as a loss-tolerant, narrow-band
reflector in the UV. We simulate device operation using a Green-function technique. Our numerical simulations indicate that
a GWS with a 25-nm grating can be used as a 95% reflector for 157-nm light, even in the presence of intensity absorptions
of 50 cm-1.
Received: 23 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-551/5035-99, E-mail: mbader@llg.gwdg.de 相似文献
17.
We describe the measurement of the line width of an atom laser beam extracted from a Bose–Einstein condensate. Using a novel
magnetic resonance imaging technique, we find that the energy width of the atom laser beam is Fourier-limited by the duration
of the output-coupling process.
Received: 25 July 2002 / Revised version: 28 October 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1254, E-mail: koehl@iqe.phys.ethz.ch 相似文献
18.
19.
V.V. Belov 《Applied physics. B, Lasers and optics》2002,75(4-5):571-576
Characteristics of object images observed through scattering media with an active vision system operating in the mode of spatial
selection are estimated using the Monte Carlo method. The effect of optical and geometrical conditions of observation on the
contrast in images of reflecting objects is considered. Interpretation is given to the obtained dependences.
Received: 11 February 2002 / Revised version: 31 May 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +7-38/2225-9086, E-mail: belov@iao.ru 相似文献
20.
M. Fally 《Applied physics. B, Lasers and optics》2002,75(4-5):405-426
Since its discovery in 1966, the photorefractive effect, i.e. the change of the refractive index upon illumination with light,
has been studied extensively in various materials and has turned out to play a key role in modern optical technologies like
photonics. This article focuses on substances that change their refractive index for neutrons when irradiated with light.
In analogy to light optics, we call them photo-neutronrefractive. After a short introduction to the relevant concepts of neutron
optics, two materials exhibiting this effect, a photopolymer and an electrooptic crystal, are presented. Further, we discuss
the progress made concerning the development of creating light-induced gratings for neutron diffraction, which culminated
in the setup of an interferometer for cold neutrons. Experiments performed on photo-neutronrefractive materials are surveyed
and the variety of corresponding results obtained is presented, including a discussion of their impact on material science,
neutron optics, and the foundations of physics.
Received: 23 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +43-1/4277-9511, E-mail: martin.fally@exp.univie.ac.at 相似文献