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1.
Frequency doubling of phase-modulated femtosecond laser pulses in periodically poled and chirped nonlinear crystals 总被引:1,自引:0,他引:1
The second harmonic generation (SHG) at a wavelength of 0.8 μm by 50-and 10-fs pulses with and without phase modulation (PM)
was systematically studied in LiNbO3 crystals with regular domain structure and linearly varied domain thickness. The main results were obtained by numerical
method, taking into account the difference between group velocities of interacting pulses and the group-velocity dispersion.
In the approximation of the given field of the fundamental radiation, an analytical expression was derived for the spectral
density of the second harmonic in the periodically poled nonlinear crystal (PPNC) under nonstationary excitation conditions.
It was numerically found that the conversion efficiency of about 90% can be achieved by doubling the frequency of 50-fs laser
pulses without PM in the LiNbO3 PPNC. The maximum conversion efficiency for the SHG by PM pulses is achieved at a certain optimum chirp step in the crystal
domain length, which depends on both the value and sign of frequency modulation. 相似文献
2.
The simultaneous generation of the 2nd and 3rd harmonics of a frequency-chirped pulse in a quadratically nonlinear medium
encompassing a quasi-phase-matched grating with linearly varying inverse domain size has been numerically studied. The efficient
pulse compression and energy conversion have been analyzed taking into account the group velocity mismatch and dispersion. 相似文献
3.
We present a scheme to produce programmable phase- and amplitude-modulated femtosecond laser pulses in the mid-infrared regime of 3-10mum by difference frequency mixing. The 80-fs signal output of an optical parametric amplifier is shaped with a liquid-crystal mask and mixed in an AgGaS(2) crystal with a temporally stretched idler pulse. Without changing the mechanical alignment, we produce programmable amplitude modulations and chirped pulses at lambda=3mum with energy as high has thas 1muJ . This scheme, further, allows the generation of controllable pulse sequences. The results are in good agreement with theoretical simulations. 相似文献
4.
The influence of the pump pulse, group-velocity mismatch, dispersion and self-phase modulation & cross phase modulation on
the phase transfer in the OPA process were analyzed. The results show that very sharp phase modulation can be maintained in
mid infrared range by optical parametric amplifier. The period and depth of the periodic modulation can also be maintained
due to small group-velocity mismatching in the calculated wavelength range. 相似文献
5.
We explore the use of a computer-controlled micro-machined deformable mirror to tailor the spectral phase of an ultrashort laser pulse to control the second-harmonic generation in KDP crystals. The SHG dependence of chirp and phase mask could be observed and adjusted by a simple theory. 相似文献
6.
N. F. Andreev V. I. Bespalov V. I. Bredikhin S. G. Garanin V. N. Ginzburg K. L. Dvorkin E. V. Katin A. I. Korytin V. V. Lozhkarev O. V. Palashov N. N. Rukavishnikov A. M. Sergeev S. A. Sukharev G. I. Freidman E. A. Khazanov I. V. Yakovlev 《JETP Letters》2004,79(4):144-147
The ultra-broadband phase matching was experimentally observed in a DKDP crystal upon parametric amplification of signal radiation with a wavelength of 911 nm in a pump field with a wavelength of 527 nm. The original scheme was used to excite the first parametric amplification stage by chirped pulses of idler radiation with a wavelength of 1250 nm. The saturated gain of a three-stage parametric amplifier was equal to 108. 相似文献
7.
8.
L. Ji P. Lu N. Dai J. Zhang Z. Yang Y. Li W. Chen Z. Jiang J. Li 《Applied physics. B, Lasers and optics》2008,91(2):295-298
We report that trefoil and quatrefoil silica channels with sizes ranging from 0.6 μm to as large as 4–5 μm in a holey fiber
can strongly confine the light field and act as highly nonlinear waveguides. Supercontinuum emissions, efficient dispersive-wave
generation and parametric four-wave-mixing processes were achieved in these channels with sub-nanojoule femtosecond Ti:sapphire
laser pulses. Two dispersion curves corresponding to two orthogonal modes in each channel were simulated and used to explain
the experimental results.
PACS 42.81.Gs; 42.81.Qb 相似文献
9.
Raoult F Boscheron AC Husson D Sauteret C Modena A Malka V Dorchies F Migus A 《Optics letters》1998,23(14):1117-1119
We demonstrate efficient generation of picosecond narrow-bandwidth pulses by frequency mixing of broadband opposite chirped pulses in a type I doubling crystal. This procedure allows us to produce picosecond pulses that are perfectly synchronized with femtosecond pulses. The experiment shows a decrease of the initial bandwidth by a factor of more than 30, while a high conversion efficiency is maintained. 相似文献
10.
It is shown experimentally that stable ~ 200 fs regular pulses and optical frequency comb spectrum containing ~ 70 discrete frequencies can be achieved using semiconductor injection laser working in the conditions of superfluorescence under dc pumping current, which is lower than the threshold of laser action. 相似文献
11.
Effects of pulse chirping on the dynamic of supercontinuum (SC) spectra generated by femtosecond laser pulses at 800 nm in calcite are studied. When an 80 fs laser pulse is stretched to more then 130 fs by introducing positive or negative chirp, a strong and sharp spectral peak in the blue wing of the SC spectra is generated. The wavelength of this spectral peak is tuned by introducing chirp and pulse energy. 相似文献
12.
V. P. Dresvyanskiy M. A. Moiseeva A. V. Kuznetsov D. S. Glazunov B. Chadraa O. Bukhtsoozh B. Zandan N. Baasankhuu E. F. Martynovich 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(1):85-88
The release of energy in the form of the light sum of thermally stimulated luminescence (TSL), stored under conditions of self-focusing and the multiple filamentation of femtosecond laser radiation during the interaction between model wide-bandgap dielectric crystals of lithium fluoride is studied. It is shown that F2 color centers are important centers of emission in the TSL process. 相似文献
13.
We introduce a novel broadband optical frequency comb generator consisting of a parametric oscillator with an intracavity electro-optic phase modulator. The parametric oscillator is pumped by 532-nm light and produces near-degenerate signal and idler fields. The modulator generates a comb structure about both the signal and the idler. Coupling between the two families of modes results in a dispersion-limited comb that spans 20 nm (5.3 THz). A signal-to-noise ratio of >30 dB in a 300-kHz bandwidth is observed in the beat frequency between individual comb elements and a reference laser. 相似文献
14.
A quantum theory of self-convers of the lasing frequency in active nonlinear crystals placed in a cavity is developed. The generation of nonclassical (quadrature squeezed) light upon self-doubling of the laser radiation frequency is studied in detail, with no limitations on the relations between the relaxation times of the inverse population and the polarization of the medium and the lifetime of a photon in the cavity. The fluctuation spectra of the quadrature components of the fields of the laser radiation and its second harmonic are studied in dependence on the pumping parameters and the parameters of the cavity. Numerical calculations are performed for a Nd:Mg:LiNbO3 crystal with a regular domain structure. 相似文献
15.
We report on the formation of one- and two-dimensional (1D and 2D) nanohole arrays on the surface of a silicon wafer by scanning with a femtosecond laser with appropriate power and speed. The underlying physical mechanism is revealed by numerical simulation based on the finite-difference time-domain technique. It is found that the length and depth of the initially formed gratings (or ripples) plays a crucial role in the generation of 1D or 2D nanohole arrays. The silicon surface decorated with such nanohole arrays can exhibit vivid structural colors through efficiently diffracting white light. 相似文献
16.
Because of their extremely high instantaneous powers, femtosecond lasers can color many nominally transparent materials. Although the excitations responsible for this defect formation occur on subpicosecond time scales, subsequent interactions between the resulting electronic and lattice defects complicate the evolution of color center formation and decay. These interactions must be understood in order to account for the long-term behavior of coloration. In this work, we probe the evolution of color centers generated by femtosecond laser radiation in potassium chloride and potassium bromide single crystals on time scales from microseconds to hundreds of seconds. By using an appropriately chosen probe laser focused through the femtosecond laser spot, we follow the changes in coloration due to individual or multiple femtosecond pulses and the evolution of that coloration for long times after femtosecond laser radiation is terminated. 相似文献
17.
18.
Domas Paipulas Viačeslav Kudriašov Mangirdas Malinauskas Valerijus Smilgevičius Valdas Sirutkaitis 《Applied Physics A: Materials Science & Processing》2011,104(3):769-773
We report studies of the modifications induced inside lithium niobate and KDP crystals by Yb:KGW ultrafast laser pulses, having
300-fs pulse duration and operating at 100-kHz repetition rate. By focusing the laser beam with a 0.42 numerical-aperture
objective, we have recorded homogeneous volume Bragg gratings in the bulk of the niobate crystal that showed excellent diffraction
efficiencies, reaching up to 87%, and remained permanent after thermal annealing for one hour at 150°C. The refractive index
modification level was found to be 0.002 in lithium niobate. The results show that lithium niobate is a very promising crystal
candidate for microphotonics applications. On the contrary, in the KDP crystal no smoothly modified refractive index zones
were created. 相似文献
19.
Frequency-shifted feedback (FSF) lasers have emerged as powerful tools for precision distance metrology. At the output of a Michelson interferometer, the detected rf spectra of the FSF laser light contain a length-dependent heterodyne beat signal whose linewidth ultimately limits the achievable accuracy of length measurements. Here, we demonstrate a narrow-linewidth chirped frequency comb from an FSF Ti:sapphire ring laser seeded by a phase-modulated, ultra-low-phase-noise, single-frequency fiber laser. We experimentally investigate the influence of the seed laser linewidth on the resulting width and shape of the length-dependent rf beat signal. An ultranarrow heterodyne beat linewidth of <20 Hz is observed. 相似文献
20.
Cross-phase-modulation-induced instability and efficient parametric frequency conversion of ultrashort light pulses 总被引:1,自引:0,他引:1
E. E. Serebryannikov S. O. Konorov A. A. Ivanov M. V. Fedorov M. V. Alfimov A. M. Zheltikov 《Journal of Experimental and Theoretical Physics》2006,102(5):707-711
We experimentally demonstrate efficient controlled parametric frequency conversion of femtosecond laser pulses through cross-phase-modulation-induced instability in the presence of a copropagating pump field in a fused silica photonic-crystal fiber. The amplitudes and the frequency shifts of sidebands generated in the spectrum of the probe field at the output of the fiber as a result of parametric four-wave mixing are controlled by varying the intensity of the pump field. 相似文献