共查询到20条相似文献,搜索用时 343 毫秒
1.
W. Holzer A. Penzkofer T. Pertsch N. Danz A. Bräuer E.B. Kley H. Tillmann C. Bader H.-H. Hörhold 《Applied physics. B, Lasers and optics》2002,74(4-5):333-342
Wave-guided thin-film distributed-feedback (DFB) polymer lasers are fabricated by spin coating a PPV-derived semiconducting
polymer, thianthrene-DOO-PPV, onto oxidised silicon wafers with corrugated second-order periodic gratings. The gratings are
written by reactive ion beam etching. Laser action is achieved by transverse pumping with picosecond laser pulses (wavelength
347.15 nm, duration 35 ps). The DFB-laser surface emission and edge emission are analysed. Outside the grating region the
polymer film is used for comparative wave-guided travelling wave laser (amplified spontaneous emission (ASE)) studies. The
pump pulse threshold energy density for wave-guided DFB-laser action (4–9 μJ cm-2) is found to be approximately a factor of two lower than the threshold for wave-guided travelling wave laser action. The
spectral width of the DFB laser (down to ΔλDFB≈0.07 nm) is considerably narrower than that of the travelling wave laser (ΔλTWL≈14 nm). The DFB-laser emission is highly linearly polarised transverse to the grating axis (TE mode). Only at high pump pulse
energy densities does an additional weak TM mode build up. The surface-emitted DFB-laser radiation has a low divergence along
the grating direction. For both the DFB lasers and the travelling wave lasers, gain saturation occurs at high excitation energy
densities.
Received: 7 January 2002 / Revised version: 15 February 2002 / Published online: 14 March 2002 相似文献
2.
E. Roissé V. Couderc A. Barthélémy F. Louradour 《Applied physics. B, Lasers and optics》1999,69(2):89-91
We report the first diode-pumped solid-state laser operating in cw-mode-locked regime and simultaneously achieving intracavity
frequency-tripling. This laser provide UV picosecond pulses (λ=355 nm) of 10 ps duration with 0.5 mW average power at 150 MHz
repetition rate. A different set of adjustments gave rise to a Q-switched mode-locked regime. Trains of hundred UV pulses
of 60 ps duration and 4 W peak power were produced in this latter case at 50 kHz repetition rate.
Received: 12 October 1998 / Revised version: 12 December 1998 / Published online: 26 May 1999 相似文献
3.
B. Köhler U. Bäder A. Nebel J.-P. Meyn R. Wallenstein 《Applied physics. B, Lasers and optics》2002,75(1):31-34
We report on an injection-seeded 9.5-W 82-MHz-repetition-rate picosecond optical parametric generator (OPG) based on a 55 mm
long crystal of periodically poled lithium niobate (PPLN) with a quasi-phase-matching (QPM) grating period of 29.75 μm. The
OPG is excited by a continuously diode pumped mode-locked picosecond Nd:YVO4 oscillator-amplifier system. The laser system generates 7 ps pulses with a repetition rate of 82.3 MHz and an average power
of 24 W. Without injection-seeding the total average output power of the OPG is 8.9 W, which corresponds to an internal conversion
efficiency of 50%. The wavelengths of the signal and idler waves were tuned in the range 1.57–1.64 μm and 3.03–3.3 μm, respectively,
by changing the crystal temperature from 150 °C to 250 °C. Injection seeding of the OPG at 1.58 μm with 4 mW of single frequency
continuous-wave radiation of a distributed-feedback (DFB) diode laser increases the OPG output to 9.5 W (53% conversion efficiency).
The injection seeding increases the pulse duration and reduces the spectral bandwidth. When pumped by 10 W of 1.06 μm laser
radiation, the duration of the signal pulses increased from 3.6 ps to 5.5 ps while the spectral bandwidth is reduced from
4.5 nm to 0.85 nm. Seeding thus improved the time-bandwidth product from 1.98 to a value of 0.56, much closer to the Fourier
limit.
Received: 29 April 2002 / Published online: 8 August 2002 相似文献
4.
Distributed feedback (DFB) lasing in permanent volume transmission gratings formed in a laser dye-doped organic–inorganic
nanocomposite has been investigated. DFB laser cavities were fabricated using one-step two-beam holographic exposure of Pyrromethene
567 (PM567) doped photopolymerizable acrylate monomers containing inorganic (LaPO4) nanoparticles. Compared to the formulation previously utilized, the material composition presented provides longer lifetime
of the laser. Spectral and polarization properties, input–output and stability characteristics of the laser output have been
investigated by varying the material composition and the patterning parameters. DFB lasing emission of the second and the
third diffraction orders has been demonstrated. The spectral linewidth of ∼0.08 nm has been observed at a pump energy threshold
of about 0.2 μJ/pulse for the second-order DFB lasing when pumped with 532 nm 500 ps laser pulses. Spectral tuning of the
lasing output over ∼56 and ∼7 nm was obtained by varying the grating period and the content of inorganic nanoparticles in
the polymer matrix, respectively. 相似文献
5.
The operation and characterization of a high-repetition-rate singly-resonant picosecond optical parametric oscillator based
on the non-linear material KTiOAsO4 and synchronously pumped by a Kerr-lens-mode-locked Ti:sapphire laser at 81 MHz is described.
By utilizing non-critical type II phase-matching in a 10 mm crystal, average near-infrared output powers of 403 mW have been
generated at 31% extraction efficiency. The oscillator exhibits a pump power threshold of 230 mW and with the available mirror
set can provide signal tuning over 1.116–1.281 μm and idler tuning over 2.260–3.160 μm by tuning the pump wavelength over
770–896 nm. Without dispersion compensation, near-transform-limited signal pulses with durations of 1.01–1.03 ps and idler
pulses with 1.61–2.91 ps duration have been obtained for 1.2 ps input pump pulses.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
6.
A synchronously mode-locked, cavity-dumped picosecond dye laser is described. The structure and intensity of the picosecond
pulses measured under different conditions are reported. It was found that the structure of the pulses from the synchronously
pumped dye laser depends critically on the length of the Ar+ laser pulses. At the shortest Ar+ laser pulses of about 70 ps the dye pulses are as short as 1.1 ps. With Ar+ laser pulses of 200 ps the dye laser pulses contains a broad satellite pulse which contains a large fraction of the total
intensity. When a cavity dumper is added to the system one gets dye laser pulses 15–20 ps long with a substructure, which
indicates incomplete mode-locking. Well mode-locked 1.5–2.0 ps pulses were obtained in the red part of the dye laser action
spectrum, i.e. 620–650 nm for R6G, 595–608 nm for R 110 and 657–662 nm for RB, respectively. Addition of mode-locking dyes
also improved the pulse quality at some wavelengths. 相似文献
7.
We report on an optical parametric amplifier (OPA) based on two potassium titanyl phosphate (KTP) crystals in a walk-off compensating
geometry. An Nd:YLF regenerative amplifier at a 1-kHz repetition rate serves as the pump source. The seed beam is delivered
by a synchronously pumped frequency-stabilized optical parametric oscillator (OPO) based on periodically poled lithium niobate
(PPLN). At pump intensities of about 7 GW/cm2 large amplification factors of more than 104 were achieved, resulting in pulse energies of more than 450 μJ and 350 μJ for the signal and idler pulses, respectively,
at a 1-kHz repetition rate. In the saturation regime the time–bandwidth product increases from two to three times the Fourier
limit, with a pulse duration of 105 ps and a bandwidth of 12.7 GHz at the highest intensities employed.
Received: 2 November 2001 / Published online: 14 March 2002 相似文献
8.
M.E. Klein A. Robertson M.A. Tremont R. Wallenstein K.-J. Boller 《Applied physics. B, Lasers and optics》2001,73(1):1-10
We theoretically and experimentally investigate wavelength tuning of synchronously pumped optical parametric oscillators (OPOs)
on changing the cavity length or the pump-repetition rate. Conditions for rapid and wide-range wavelength access are derived.
Using an OPO pumped directly by a mode-locked diode-laser master-oscillator power-amplifier (MOPA) system, an all-electronically
controlled access to near- and mid-infrared wavelengths is demonstrated. The singly (signal) resonant OPO is based on periodically
poled lithium niobate (PPLN) and emits 8 ps idler pulses at a repetition rate of 2.5 GHz in the wavelength range 1986 to 2348 nm
(signal: 1530 to 1737 nm). Wavelength tuning over 114 nm (signal) and 189 nm (idler) is achieved solely by electronically
varying the repetition rate of the diode-laser oscillator over 720 kHz. By controlling the repetition rate with a programmable
driver, an arbitrary emission sequence of the OPO on two wavelength channels is generated, with access times as short as 10 μs.
11 OPO wavelengths equally spaced in the range 1627–1689 nm (signal) or 2054–2154 nm (idler) could be addressed.
Received: 6 September 2000 / Revised version: 16 March 2001 / Published online: 23 May 2001 相似文献
9.
For the first time, tunable lasing from a dye laser with an active polymer medium has been obtained using 1.06 μm pumping.
The conversion efficiency of 43% and the tunable range of Δλ=63 nm have been reached with the use of polymethine dye in a
polyurethane matrix.
Received: 20 April 2001 / Revised version: 16 July 2001 / Published online: 19 September 2001 相似文献
10.
Sumei Wang Qinan Li Qiulin Zhang Jie Xing Baohua Feng Shiwen Zhang 《Optics Communications》2007,277(1):130-133
Simultaneous self-Q-switched and mode-locked have been demonstrated in a diode-pumped Nd,Cr:YAG laser. For the first time as we know, almost 100% modulation depth has been achieved at an intracavity intensity of 5.6 × 105 W/cm2. The maximum average output power of 6.52 W corresponding to a slope efficiency of 30% is obtained at 1064 nm. The laser produces high-quality pulses in a TEM00-mode at the pump power of 16.5 W. The pulse duration of the mode-locked pulses is about 600 ps with 136 MHz repetition rate. 相似文献
11.
Picosecond pulses from a mode-locked Nd:YAG laser and a traveling-wave dye laser are mixed in an AgGaS2 crystal to generate pulses at the difference frequency. The dye laser is tunable between 1200 nm and 1460 nm resulting in a tuning range of the parametric pulses from 3.9 μm to 9.4 μm. The spectral bandwidth is quite narrow. A value of Δ?=6.5 cm-1 was measured which is constant over the whole tuning range. Several percent of the Nd:YAG laser photons are converted to infrared photons. Pump pulses of 21 ps give parametric pulses of 8 ps. 相似文献
12.
G. Seifert M. Kaempfe K.-J. Berg H. Graener 《Applied physics. B, Lasers and optics》2001,73(4):355-359
By repetitive irradiation of pico- or femtosecond laser pulses on glasses containing silver nanoparticles, dichroitic areas
can be produced with different optical properties depending on the actual irradiation parameters. This effect, which is nanoscopically
caused by permanent deformation of the initially spherical particles to non-spherical shapes and an additional formation of
a halo of very small particles, is studied as a function of polarization and number of the applied pulses using two different
laser systems (Ti:sapphire, λ=400 nm, tp=150 fs; Nd:YLF, λ=523.5 nm, tp=4 ps). A very special diffraction grating produced by this local deformation, which has strongly polarization- and wavelength-dependent
features, is introduced and discussed.
Received: 20 July 2001 / Published online: 10 October 2001 相似文献
13.
J. Chen H. Mizuno H. Kawano A. Miyawaki K. Midorikawa 《Applied physics. B, Lasers and optics》2006,85(1):45-48
We experimentally demonstrated two-photon pumping of random lasers using picosecond and nanosecond pump lasers. The picosecond laser pumping experiment was performed with 400 ps laser pulses at 770 nm, and the gain media was a Coumarin 480D dye solution doped with TiO2 nanoparticles. Onset of laser action was observed at a pump laser pulse energy below 500 μJ. The nanosecond laser pumping experiment was performed with 7 ns laser pulses at 1064 nm, and the gain media was a Rhodamine 640 dye solution doped with TiO2 nanoparticles. Onset of laser action was observed at a pump laser energy ∼18 mJ. Our results suggest that there exists an optimal pulse duration of the pumping laser in two-photon pumped random lasing that leads to minimum photodamage of the gain media and still keeps a high pumping efficiency. PACS 33.50.Dq; 42.55.Mv; 42.55.Zz 相似文献
14.
Changwen Xu Kunna He Dehua Li Yongdong Zhang Zhiguo Zhang 《Optics Communications》2008,281(17):4398-4400
We have demonstrated the stable mode-locked Nd:GdVO4 laser operating on the 4F3/2-4I9/2 transition at 912 nm. With a four-mirror-folded cavity and a semiconductor saturable absorber mirror for passive mode-locking, we have gained 6.5 ps laser pulses at a repetition rate of 178 MHz. The laser is diode-end-pumped, and the total output power from the out coupler is 128 mw at an incident pump power of 19.7 W. 相似文献
15.
Passively Mode-Locked Quasi-Three-Level Nd:LuVO4Laser with Semiconductor Saturable Absorber Mirror 下载免费PDF全文
We demonstrate a passively a Z-folded resonator. Using device, we achieve stable cw average output power under cw mode-locked Nd:LuVO4 laser operating on the quasi-three-level at 916nm with a semiconductor saturable absorber mirror (SESAM) as the passive mode-locking mode locking with 6.7ps pulse duration at repetition rate of 133 MHz and 88mW the pump power of 17.1 W. 相似文献
16.
E.G. Gamaly A.V. Rode A. Perrone A. Zocco 《Applied Physics A: Materials Science & Processing》2001,73(2):143-149
We present two sets of experimental results on the ablation-rate decrease with increase of the number of consecutive laser
pulses hitting the same spot on the target surface. We have studied laser ablation of a carbon target with nanosecond pulses
in two different interaction regimes: one with a XeCl laser (λ=308 nm) and the other with a Nd:YAG laser (λ=1064 nm), in both
cases at the intensity ∼5×108 W/cm2 Two different mechanisms were found to be responsible for the ablation-rate decrease; they are directly related to the two
different laser–matter interaction regimes. The UV-laser interaction is in the regime of transparent vapour (surface absorption).
The increase of the neutral vapour density in the crater produced by the preceding laser pulses is the main reason for the
decrease of ablation rate. With the IR laser each single laser pulse interacts with a partially ionised plume. With increase
of the number of pulses hitting the same spot on the target surface, the laser–matter interaction regime gradually changes
from the near-surface absorption to the volume absorption, resulting in the decrease in absorption in the target and thus
in the decrease in the ablation rate. The change in the evaporation rate was considered for both vacuum and reactive-gas environments.
Received: 21 February 2001 / Accepted: 26 February 2001 / Published online: 23 May 2001 相似文献
17.
We present experimental and theoretical results on the characteristics and random variations of subpicosecond pulses generated by a synchronously pumped cw dye laser with saturable absorber. The analysis of the power spectra indicates rapid fluctuations of the pulse duration of 40–50%, energy fluctuations of 3%, and a jitter of the repetition time of 0.1% corresponding to an absolute jitter of 12 ps. The latter is caused mainly by the temporal jitter of the pump laser. A mismatch of the lengths of the dye and the pump-laser cavity can result in a nonstationary mode-locking regime with a periodic change of the pulse parameters. The interpretation of the experimental results are supported by computer simulations of the pulse evolution process. 相似文献
18.
Qinan Li Sumei Wang Yuxian Shi Dongxiang Zhang Zhiguo Zhang 《Optics Communications》2008,281(8):2184-2188
A simultaneous self-Q-switched and mode-locked diode-pumped 946 nm laser by using a Cr,Nd:YAG crystal as gain medium as well as saturable absorber is demonstrated for the first time as we know. The maximum average output power of 751 mW with a slope efficiency of 18.38% is obtained at an intra-cavity average peak power intensity of 4.83 × 106 W/cm2. Under this circumstance, the repetition rate of Q-switched envelopes is 9.63 kHz and the pulse width is about 460 ns. Almost 100% mode-locked modulation depth is obtained at all time in the experiment process whether the incident pump power is low or high. The repetition rate of mode-locked pulses within a Q-switched envelope is 135.13 MHz and the mode-locked pulse width is within 600 ps. The laser produces high-quality pulses in TEM00-mode in the simultaneous self-Q-switched and mode-locked experiment. 相似文献
19.
New results in the experimental study of the spectro-temporal selection (STS) method to produce picosecond dye laser pulses are presented. Adjustability of the picosecond pulse wavelength, possibility of extension of the STS method to different dyes and to UV pump wavelength, stability of the output pulse duration and intensity, and the concentration effect on pulse duration, are reported for the first time. From these results, production of high power picosecond (50–100 ps) dye laser pulses spectrally adjustable between 400 and 700 nm is obtained with a standard nanosecond pump laser, in a compact and simple device. 相似文献
20.
T. Rothacher W. Lüthy H.P. Weber 《Applied Physics A: Materials Science & Processing》2001,73(2):133-136
According to UN estimations there are between 80 and 115 million activated landmines worldwide. These mines, or other unexploded
ordnance (UXO), can be triggered accidentally and kill or injure more than 2000 civilians per month. The most common explosive
in these mines is trinitrotoluene (TNT). In this paper, the potential of some of the most promising lasers for mine neutralisation
is investigated, namely an ArF laser, a KrF excimer laser and a Nd:YAG solid-state laser. We have studied the interaction
between laser beams emitting at λ=193 nm, 248 nm and 1060 nm and a bare solid sample of TNT of approximately 15 mg. Using
pulsed excimer radiation at λ=193 nm, with an energy density up to 1 J/mm2, ablation of the TNT without any deflagration has been achieved. At λ=248 nm, using the KrF excimer laser with a pulse duration
of 30 ns and a repetition rate of 5 Hz, the TNT sample started melting and burning after an irradiation of 10 s. Preliminary
results with the Nd:YAG solid-state laser operating in cw emission have shown that the irradiated sample exhibits the desired
burning behaviour even after the exposure is stopped.
Received: 14 December 2000 / Accepted: 18 December 2000 / Published online: 20 June 2001 相似文献