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Relation among group delay, energy storage and loss in dispersive dielectric mirrors
P.G. Antal, R. Szipocs || 2012
Abstract:
We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in
highly reflective dispersive dielectric mirrors over the high-reflectivity band. Our theoretical considerations
are verified by numerical simulations performed on different dielectric mirror structures. The revealed proportionality
between group delay and absorbed energy sets constraint on the application of ultrabroadband
and/or dispersive dielectric mirrors in broadband or widely tunable, high power laser systems.
Tunable, low-repetition-rate, cost efficient femtosecond Ti:sapphire laser for nonlinear microscopy
P.G. Antal, R. Szipocs || 2011
Abstract:
We report on a broadly tunable, long-cavity
Ti:sapphire laser oscillator being mode-locked in the net
negative intracavity dispersion regime by Kerr-lens mode-locking,
delivering τFWHM < 300 fs pulses at 22 MHz repetion
rate. The wavelength of the laser can be tuned over
a 170 nm wide range between 712 nm and 882 nm. Having
a typical pump power of 2.6 W, the maximum pulse
peak power is 60 kW. Comparison of the reported laser
with a standard, 76 MHz Ti:sapphire oscillator regarding
two-photon excitation efficiency in a laser scanning microscope
shows that the 22 MHz laser generates the same fluorescence
signal at considerably, 1.82 times lower average
power, which is expected to result in a reduced photothermal
damage probability of biological samples. This fact along
with the broad tunabiéity and a low pump power requirement
makes this cost-effective laser and ideal light source for
nonlinear microscopy.
Photonic bandgap fibers with resonant
structures for tailoring the dispersion Z. Varallyay, K. Saitoh, A. Szabo, and R. Szipocs || 2009
Abstract:
Numerical simulations on different kinds of realistic photonic bandgap fibers exhibiting reversed dispersion slope for the propagating fundamental mode are reported. We show that reversed or flat dispersion
functions in a wide wavelength range using hollow-core, air-silica photonic bandgap fibers and solid core Bragg fibers with step-index profile can be obtained by introducing resonant structures in the fiber cladding. We evaluate the dispersion and confinement loss profiles of these fibers from the Helmholtz eigenvalue equation and the calculated fiber properties are used to investigate the propagation of chirped femtosecond pulses through serially connected hollow core fiber compressors
All-fiber, all-normal dispersion ytterbium ring oscillator J. Fekete, A. Cserteg, and R. Szipocs || 2008
Abstract:
Experimental results on an all-fiber, all-normal dispersion ytterbium ring laser are reported. It produces stable mode-locking of ~10 ps pulses that can be externally compressed to as short as ~200 fs.
Reversed dispersion slope photonic bandgap fibers for broadband dispersion control in femtosecond fiber lasers Z. Varallyay, K. Saitoh, J. Fekete, K. Kakihara, M. Koshiba, and R. Szipocs || 2008
Abstract:
Higher-order-mode solid and hollow core photonic bandgap
fibers exhibiting reversed or zero dispersion slope over tens or hundreds of
nanometer bandwidths within the bandgap are presented. This attractive
feature makes them well suited for broadband dispersion control in femtosecond
pulse fiber lasers, amplifiers and optical parametric oscillators.
The canonical form of the dispersion profile in photonic bandgap fibers
is modified by a partial reflector layer/interface placed around the core
forming a 2D cylindrical Gires-Tournois type interferometer. This small
perturbation in the index profile induces a frequency dependent electric
field distribution of the preferred propagating higher-order-mode resulting
in a zero or reversed dispersion slope.
Design of high-bandwidth one- and two-dimensional photonic bandgap dielectric structures at grazing incidence of light J. Fekete, Z. Varallyay, and R. Szipocs || 2008
Abstract:
We propose one-dimensional photonic bandgap (PB) dielectric structures to be used at grazing incidence
in order to obtain an extended bandgap exhibiting considerably reduced reflection loss and dispersion
compared to similar structures used at a normal incidence of light. The well-known quarter-wave
condition is applied for the design in this specific case, resulting in resonance-free reflection bands without
drops in reflection versus wavelength function and a monotonous variation of the group delay dispersion
versus wavelength function, which are important issues in femtosecond pulse laser applications. Based
on these results we extend our studies to two-dimensional PB structures and provide guidelines to the
design of leaking mode-free hollow-core Bragg PB fibers providing anomalous dispersion over most of the
bandgap.
Chirped-pulse supercontinuum generation with a long-cavity Ti:sapphire oscillator P. Dombi, P. Antal, J. Fekete, R. Szipőcs, Z. Várallyay || 2007
Abstract: We demonstrate chirped-pulse supercontinuum generation in a conventional fibre with a relatively narrowband,
long-cavity, chirped-pulse Ti:sapphire oscillator delivering
200 nJ pulses. The inherent chirp of the outcoupled pulses
were overcompensated by a 4-prism compressor to overcome
damage threshold problems at the fibre entrance. The resulting
fibre output spectrum corresponds to a pulse length of 7 fs in the
transform-limit. The experimentally observed highly efficient
spectral broadening process of negatively chirped pulses in the
fibre is supported by simulation data.
Optimizing input and output chirps up to the third-order for sub-nanojoule, ultra-short pulse compression in small core area PCF Z. Várallyay, J. Fekete, Á. Bányász, R. Szipőcs || 2006
Abstract: Compression of sub-nanojoule laser pulses using a commercially available photonic crystal fiber (PCF)with zero dispersion wavelength of 860 nm is discussed. A twofold pulse
compression starting from 24 fs transform limited seed pulses
around 800 nm is experimentally demonstrated as a verification
of our simulations. Theory shows that by the optimization of
input and output chirp parameters up to the third order, high
quality, 5.7 fs pulses can be generated from a cost efficient experimental setup. Further calculations show that 1 ps pulses with
central wavelength of 800 nm can be compressed down to 50 fs
in the normal dispersion regime of the fiber with proper dispersion
compensation. Calculations also show that dispersion
flattened fibers can improve both the quality and the duration of
compressed pulses.
Random access three-dimensional two-photon microscopy Balázs Rózsa, Gergely Katona, E. Sylvester Vizi, Zoltán Várallyay, Attila Sághy, László Valenta, Pál Maák, Júlia Fekete, Ákos Bányász, and Róbert Szipőcs || 2006
Abstract: We propose a two-photon microscope scheme capable of real-time, three-dimensional investigation of the electric activity pattern of neural networks or signal summation rules of individual neurons in a 0.6 mm x 0.6 mm x 0.2 mm volume of the sample. The points of measurement are chosen according to a conventional scanning two-photon image, and they are addressed by separately adjustable optical fibers. This allows scanning at kilohertz repetition rates of as many as 100 data points. Submicrometer spatial resolution is maintained during the measurement similarly to conventional two-photon microscopy.
Trends in Optics and Photonics Series || TOPS Vol 98, Series editor Alexander A. Sawchuck || 2005, Optical Society of America
Sub-nanojoulepulse compression in small core area photonic crystal fibers below the zero dispersion wavelength by Z. Várallyay, J. Fekete, Á.Bányász, R. Szipőcs || p. 571-576
Low reflection loss ion-beam sputtered negative dispersion mirrors with MCGTl structure for low pump threshold, compact femtosecond pulse lasers by B. Császár, A. Koházi- Kis, F. Szipőcs & R. Szipőcs || p 674-679
Cubic phase distortion of single attosecond pulses being reflected on narrowband Mo/Si filtering mirrors by András Lukács, Zoltán Várallyay, Róbert Szipőcs || p. 806-810
Real time 3D nonlinear microscopy B. Rozsa, E. S. Vizi, G.Katona, A. Lukács, Z. Várallyay, A. Sághy, L. Valenta, P. Maák, J. Fekete, Á. Bányász, R. Szipőcs || p. 858-863
Broad tunability from a compact, low-threshold
Cr:LiSAF laser incorporating an improved birefringent filter and multiple-cavity Gires-Tournois interferometer mirrors by Barry Stormont, Alan J. Kemp, Iain G. Cormack, Ben Agate, C. Tom A. Brown, and Wilson Sibbett and Róbert Szipőcs || 2005
Abstract: We demonstrate prismless tuning of a compact femtosecond Cr:LiSAF laser. The employed technique, which
uses a specially designed birefringent filter in combination with dispersion compensation from a pair of
multiple-cavity Gires-Tournois interferometer mirrors, provides tuning over 20 nm. We give the results of theoretical
modeling of the tuning velocity and the spectral width of the central passband. We show, both experimentally
and theoretically, that a single birefringent plate can be used to control the oscillating bandwidth of
the laser. The effect this has on the output-pulse duration has also been investigated.
2005 Conference on Lasers and Electro-Optics, Quantum Electronics and Laser Science, May22-27, Baltimore, MD, USA || The four articles presented at the CLEO 2005 conference are now available online.
Nonlinear
refraction and absorption of Mg doped stoichiometric and congruent LiNbO3 by L. Pálfalvi, G. Almási, Á. Péter, K. Polgár,
K. Lengyel, and R. Szipőcs || February 2004
Abstract: The light induced change of refraction
is studied in pure and Mg doped LiNbO3 with congruent and stoichiometric
compositions by the Z-scan method using all-lines visible argonion laser,
up to MW/cm intensity
level. In Mg-doped congruent and stoichiometric crystals with Mg concentrations
above threshold a positive change in the refractive index was found,
in contrast to all other cases where beam fanning and negative change
of the refractive index were observed.
Pulse
compression of nanojoule pulses in the visible using microstructure optical
fiber and dispersion compensation by S. Lakó, J. Seres,
P. Apai, J. Balázs, R.S. Windeler, and R. Szipőcs || June 2002
Abstract: Experimental results on the pulse
compression of 1-nJ, 150-fs pulses from a tunable, 76-MHz Ti:sapphire
laser oscillator operating at around 750 nm are reported. The length
of the pulses can be compressed to nearly one tenth by applying a high-delta,
single-mode microstructured optical fiber exhibiting zero group-delay
dispersion at 767 nm, and by a prismpair/ chirped-mirror compressor.
The experimental results are verified by theoretical investigations
modeling the pulse propagation taking into account non-linear self-phase
modulation and fiber dispersion. PACS 42.65; 42.81
Spectral
filtering of femtosecond laser pulses by interference filters
by R. Szipőcs, A.Köházi-Kis, P. Apai, E. Finger, A. Euteneuer M.Hofmann
|| October 1999
Abstract: Phase properties of optical thin film
interference filters are discussed from the aspect of their usage for
phaseerror free wavelength separation of broadband femtosecond laser
pulses. It is shown that both transmissive or reflective interference
filters with high contrast ratios exhibit high cubic phase shifts on
transmission or reflection, respectively, causing intolerable distortion
in the temporal pulse shape. We show, however, that high efficiency
wavelength separation of broadband femtosecond laser pulses can be achieved
by using low contrast, properly designed reflective optical interference
filters directly built into the cavity of the broad spectrum, femtosecond
pulse lasers or parametric oscillators. For demonstrative purposes,
we implemented the idea for a Kerrlens mode-locked Ti:sapphire laser,
and obtained two-color, inherently synchronized, unchirped, femtosecond
pulse outputs from a single laser oscillator.
Negative
dispersion mirrors for dispersion control in femtosecond lasers: chirped
dielectric mirrors and multi-cavity Gires-Tournois interferometers by
R. Szipőcs, A.Köházi-Kis, S. Lakó, P. Apai, A.P.Kovács,
G. DeBell, L.Mott, A.W. Louderback, A.V. Tikhonravov, M.K. Trubetskov
|| October 1999
Abstract. Chirped dielectric laser mirrors
have been known for years as useful devices for broadband feedback and
dispersion control in femtosecond pulse lasers. First we present a novel
design technique referred to as frequency domain synthesis of chirped
mirrors. These mirrors exhibit high reflectivity and nearly constant
group delay over 150 THz supporting generation of sub-5-fs pulses in
the visible...
Measurement
of dispersive properties of optical materials and mirrors using spectrally
resolved white- light interferometry by Zsolt Bor, Attila P Kovács,
Károly Osvary and Róbert Szipőcs || April 1998
Abstract: We present a simple, accurate and
inexpensive interferometric technique based on spectrally resolved white-light
iterferometry to determine the group-delay dispersion of optical elements,
such as layer crystals and multilayer mirrors. Due to the different
dispersion of these elements, different evaluation methis of interference
fringes are used for the mirrors and crystals.
A
Compact All-Solid-State Sub-5fsec Laser by Andrius Baltu ka,
Maxim S Pschenichnikov, Róbert Szipőcs, Douwe A. Wiersma || December
1997
Abstract: n/a
Sub-20
fs pulse generation from the mirror dispersion controlled Cr:LiSGaFandCr:LiSAFlasers
by I.T. Sorokina, E. Sorokin, E.Wintner, A. Cassanho, H.P. Jenssen and
R. Szipőcs || May 1997
Abstract: We describe the state of the art of
mirror-dispersioncontrolled (MDC) Kerr-lens mode-locked (KLM) Cr:LiSGaF
and Cr:LiSAF lasers. Such lasers, in comparison to their prism-controlled
forerunners, are distinguished by high reproducibility, stability, and
quality of the pulses, as well as compactness of the cavity. The shortest
pulses of ~18 fs duration and nearly bandwidth-limited quality (
= 0.33) have been produced in Cr:LiSGaF lasers, which have an average
output power of 100mW. In both lasers, krypton-laser was used as an
ideal pump source. The effect of a red-shift of the operating wavelength
(from 850 to 880 nm) when shortening of the pulse width (from ~ 50 fs
to ~ 20 fs) has been observed and discussed.
Theory
and design of chirped dielectric laser mirrors by A.Kõházi-Kis
and R. Szipőcs || April 1997
Abstract: Chirped dielectric laser mirrors offer
a general solution for broadband feedback and dispersion control in
femtosecond laser systems. Chirped mirrors developed for modelocked
solid-state lasers, femtosecond parametric oscillators, chirped pulse
amplification systems and pulse compressors are introduced. Basic theoretical
and design considerations are also presented.
All-solid-state
cavity-dumped sub-5-fs laser by A. Baltuka1,
Z.Wei, M.S. Pshenichnikov, D.A. Wiersma, Róbert Szipőcs || March 1997
Abstract. We discuss in detail a compact all-solid-state
laser delivering sub-5-fs, 2-MW pulses at repetition rates up to 1MHz.
The shortest pulse generated thus far measures only 4:6 fs. The laser
system employed is based on a cavitydumped Ti:sapphire oscillator whose
output is chirped in a single-mode fiber. The resulting white-light
continuum is compressed in a novel high-throughput prism chirped-mirror
Gires-Tournois interferometer pulse compressor. The temporal and spectral
phase of the sub-5-fs pulses are deduced from the collinear fringe-resolved
autocorrelation and optical spectrum. The derived pulse shape agrees
well with the one retrieved from the measured group delay of the continuum
and calculated characteristics of the pulse compressor.
Ultrabroadband
chirped mirrors for femtosecond lasers by E. J. Mayer, J. Möbius,
A. Euteneuer, and W. W. Rühle and R. Szipőcs || November 1996
Abstract: We report on the performance of widely
tunable femtosecond and continuous-wave Ti:sapphire lasers that use
a newly developed ultrabroadband mirror set. The mirrors exhibit high
ref lectivity (R > 99%) and smooth variation of group delay versus
frequency over a wavelength range from 660 to 1060 nm. Mode-locked operation
with pulse durations of 85 fs was achieved from 693 to 978 nm with only
one set of ultrabroadband mirrors.
Prismless
passively mode-locked femtosecond Cr:LiSGaF laser by I. T. Sorokina,
E. Sorokin, and E. Wintner, A. Cassanho, H. P. Jenssen and R. Szipőcs
|| February 1996
Abstract: A Kerr-lens mode-locked Cr:LiSrGaF
laser containing no intracavity prisms has been demonstrated for the
first time to the authors' knowledge. The laser produced stable near-transform-limited
44-fs pulses with an output power of 200 mW, tunable between 833 and
857 nm. Low-loss Gires-Tournois structured dielectric mirrors were used
for dispersion control. The measured group-delay dispersion of the active
medium as well as of the mirrors permitted to minimize the number of
ref lections, permitting higher output power.
Ultrabroadband
ring oscillator for sub-10-fs pulse generation by Lin Xu, Christian
Spielmann, Ferenc Krausz and R. Szipőcs || January 1996
Abstract: A four-mirror ring cavity formed by
chirped dielectric mirrors is proposed for self-mode-locked solid-state
lasers. It offers, for the first time to our knowledge, the potential
for approaching the gain-bandwidth limit in Ti:sapphire and related
broadband lasers. Using this concept, we produced nearly bandwidth-limited
7.5-fs pulses from a feedback-initiated, self-mode-locked Ti:sapphire
ring oscillator. Our experiments provide new insight into the physics
and limitations of sub-10-fs oscillators.
Chirped
dielectric mirrors improve Ti:sapphire lasers by Ch. Spielmann,
M. Lenzner, R. Szipőcs and F. Krausz || December 1995
Abstract: High quality seed pulses from mirror
dispersion-controlled Ti:sapphire system allow chirped pulse amplification
without a pulse strectcher.
Compact,
high-throughput expansion-compression scheme for chirped pulse amplification
in the 10 fs range by Ch. Spielmanna, M. Lenzner, F. Krausz, R.
Szipőcs || July 1995
Abstract: A novel pulse stretching-compression
system suitable for kHz-rate chirped-pulse amplification of ~10 fs pulses
in Ti:sapphire systems is demonstrated. The material dispersion of the
system components used for pulse selection and isolation broadens the
wide-band seed pulses by a factor of -300, allowing amplification up
to the submillijoule energy range. The compressor consists of a pair
of prisms and newly-developed chirped multilayer dielectric mirrors
for compensating high order dispersion. Using this simple scheme a recompression
of unamplified pulses down to 15 fs with a throughput as high as 80%
is demonstrated.
Pushing
the limits of Femtosecond Technology: Chirped Dielectric Mirrors
by Róbert Szipőcs, Andreas Sitingl, Christian Spielmann and Ferenc
Krausz || June 1995
Abstract: The authors explain the theory behind
the ultrashort pulses and offer a new method - chirped dielectric mirrors
- for achieving.
Measurement
of the group delay of laser mirrors by a Fabry-Perot interferometer
by K. Osvay, G. Kurdi, J. Hebling, A. P. Kovács, Z. Bor and R.
Szipőcs || June 1995
Abstract: The group delay of multilayer laser
mirrors was measured by determining the spectral position of transmission
maxima of a Fabry–Perot interferometer formed by the mirrors to be characterized.
By optimizing the spacer thickness, we obtained an accuracy of the group-delay
measurement of better than 0.23 fs. To our knowledge, this is the most
precise direct measuring method reported.
Chirped-mirror
dispersion-compensated femtosecond optical parametric oscillator
by J. Hebling, E. J. Mayer, J. Kuhl, R. Szipőcs || January 1995
Abstract: We describe the operating characteristics
of a femtosecond optical parametric oscillator employing chirped mirrors
for intracavity group-velocity dispersion compensation. Pumped by 760
mW of power from a self-mode-locked Ti:sapphire laser, this device provides
100-fs near-transform-limited pulses continuously tunable from 1.18
to 1.32 mm with an average power of 100-180 mW. The limitations of the
present setup and strategies for further pulse shortening are discussed.
Group-delay
measurement on laser mirrors by spectrally resolved white-light interferometry
by A. P. Kovács, K. Osvay, Zs. Bor and R. Szipőcs || October 1994
Abstract: The frequency-dependent group delay
of dielectric mirrors was measured by spectrally resolved white-light
interferometry. Chirped mirrors and thin-film Gires-Tournois interferometers
designed for dispersion control in a femtosecond Ti:sapphire laser oscillator-amplifier
system were tested with a group-delay resolution of 60.2 fs and a spectral
resolution of ,1 nm over the spectral range of 670-870 nm.
Sub-10-fs
mirror-dispersion-controlled Ti:sapphire laser by A. Stingl, M.
Lenzner, Ch. Spielmann, and F. Krausz and R. Szipőcs || October 1994
Abstract: We demonstrate the generation of nearly
bandwidth-limited 8-fs optical pulses near 0.8 mm from a self-modelocked
Ti:sapphire laser oscillator, using chirped dielectric mirrors for dispersion
control. The mode-locking performance is described, and limitations
are discussed.
Design
of dielectric high reflectors for dispersion in femtosecond lasers
by Róbert Szipőcs, Ambrus Kõházi-Kis || June 1994
Abstract: Chirped dielectric rugate mirrors
were constructed for broadband dispersion control in femtosecond laser
oscillators by Fouries transform. Dispersive properties of the mirrors
are tailored and explained on the basis of the time shifting theorem
of Fourier analysis. Depending on their construction parameters, these
chirped gradientüindex structures exhibit high reflectivity amd
neary constamt negative, i.e. anomalous, group delay dispersion over
frequency ranges well beyond the currently available fluorescence bandwidth
of broadbanc laser-active materials. As a consequence, practical implementation
of these novel dispersive devices would permit the full utilisation
of the bandwidth offered by these broadband gain media, and allow the
construction of small, compat femtosecond solid state laser oscillators
generating optical pulses shorter than those achieved so far, directly
from the laser oscillator.
Tunneling
of Optical Pulses through Photonic Band Gaps by and Ch. Spielmann,
F. Krausz, A. Stingl and R. Szipőcs || April 1994
Abstract: Propagation of electromagnetic wave
packed through ID photonic band gap materials has been studies using
12 fs optical pulses. The measured transit time is found to be paradoxically
short (implying superluminal tunneling) and independent of the barriers
thickness for opaque barriers, in analogy to the behavior of electrons
tunneling through potential barriers. Shortening of Fourier-limited
incident wave packets is observed upon transmission through these linear
systems. Although in apparent conflict with causality and the uncertainty
principle, neither of these general principles is violated because of
the strong attenuation suffered by the transmitted signals.
Generation
of 11-fs pulses from a Ti:sapphire laser without the use of prisms
by Andreas Stingl, Christian Spielmann, Ferenc Krausz and Róbert
Szipőcs || September 1993
Abstract: The generation of highly stable optical
pulses as short as 11 fs from a Kerr-lens mode-locked Ti:sapphire laser
containing no intracavity prisms is demonstrated. In the femtosecond
oscillator design reported, novel dielectric mirrors provide broadband
dispersion control for solitonlike pulse formation.
Chirped
multilayer coatings for broadband dispersion control in femtosecond lasers
by Robert Szipőcs, Kárpát Ferencz, Christian Spielmann and
Ferenc Krausz || August 1993
Abstract: Optical thin-film structures exhibiting
high reflectivity and a nearly constant negative group-delay dispersion
over frequency ranges as broad as 80 THz are presented. This attractive
combination makes these coatings well suited for intracavity dispersion
control in broadband femtosecond solid-state lasers. We address design
issues and the principle of operation of these novel devices...
Recent
Developements of Laser Optical Coatings in Hungary by Kárpát
Ferencz and Robert Szipőcs || October 1993
Abstract: Optical coating suppliers specialized to meet pecial
needs of laser developers often have to face challenges to help them
in building high-performance, high-efficiency lasers. Some aspects of
laser optical coating design and manufacturing are discussed.
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