共查询到20条相似文献,搜索用时 31 毫秒
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.
3.
Amplification of femtosecond pulses at 1.56 microm based on noncollinear parametric chirped pulse amplification in a potassium titanyl arsenate (KTA) crystal with pumping at 1.05 microm is reported. The 100 fs pulses of an erbium fiber laser are parametrically amplified while synchronously pumped by an amplified mode-locked Nd:YLF laser. This amplifier has a saturated gain of 65 dB with 30% conversion efficiency and has produced 160 fs pulses with peak powers of up to 0.75 GW. The system produced 380 mW before compression and can be readily scaled to the multiwatt range with bandwidths to support sub-100 fs pulses. 相似文献
4.
Schulz M Riedel R Willner A Mans T Schnitzler C Russbueldt P Dolkemeyer J Seise E Gottschall T Hädrich S Duesterer S Schlarb H Feldhaus J Limpert J Faatz B Tünnermann A Rossbach J Drescher M Tavella F 《Optics letters》2011,36(13):2456-2458
We report on a Yb:YAG Innoslab laser amplifier system for generation of subpicsecond high energy pump pulses for optical parametric chirped pulse amplification (OPCPA) at high repetition rates. Pulse energies of up to 20 mJ (at 12.5 kHz) and repetition rates of up to 100 kHz were attained with pulse durations of 830 fs and average power in excess of 200 W. We further investigate the possibility to use subpicosecond pulses to derive a stable continuum in a YAG crystal for OPCPA seeding. 相似文献
5.
We present a quantum theory of the parametric self-conversion of the laser radiation frequency in active nonlinear crystals with a regular domain structure. Such crystals feature simultaneous lasing and quasi-phase-matched parametric conversion of the laser radiation frequency. These processes are described using the Heisenberg-Langevin equations in two regimes of the subharmonic generation: super-and subthreshold. The spectral properties of the quadrature components of the laser frequency and its subharmonic and the photon statistics have been studied as dependent on the pump power, crystal length, and reflectance of the laser cavity output mirror. Using the obtained analytical expressions, these characteristics are calculated for a active nonlinear Nd:Mg:LiNbO3 crystal with a regular domain structure. In the subthreshold regime, the maximum decrease in the spectral density of fluctuations in the subharmonic quadrature component relative to the standard quantum limit may reach 90%; in the above-threshold regime, these fluctuations are virtually not suppressed. A decrease in the spectral density of fluctuations of the laser frequency quadrature does not exceed 10%. In the subthreshold excitation regime, the subharmonic photons obey a super-Poisson statistics; in the above-threshold regime, the photon statistics is Poisson-like. 相似文献
6.
7.
通过研究光参量啁啾脉冲放大过程转换效率随泵浦光啁啾参数的变化,以及信号光和泵浦光波长的对应关系,确立了信号光和泵浦光同步时实现线性啁啾匹配的方法。以磷酸二氢钾作为非线性晶体,研究了信号光和泵浦光之间的线性啁啾匹配和时间同步抖动对光参量啁啾脉冲放大后信号光脉冲波形和转换效率的影响。结果表明:在时间同步的情况下,线性啁啾匹配时的信号光脉冲波形很对称,转换效率也较高;在同步抖动程度一定的情况下,不同泵浦光啁啾参数时,信号光的增益及放大后的脉冲波形差异较大;在线性啁啾匹配程度一定时,信号光和泵浦光时间同步抖动越严重,放大信号光的脉冲波形变化越大,信号光增益越小,且转换效率也越低。 相似文献
8.
V. Pyragaite A. Stabinis R. Butkus R. Antipenkov A. Varanavi?ius 《Optics Communications》2010,283(6):1144-1151
We present simple analytical solutions of coupled wave equations describing chirped pulse parametric amplification under pump depletion. The evolution of the duration and spectrum of amplified pulses in OPA pumped by Gaussian and supergaussian pulses has been investigated both numerically and analytically. Also, the dependence of the energy conversion efficiency from pump to signal was determined for a range of parameter values, and an optimum ratio of signal and pump pulse durations was evaluated. 相似文献
9.
Generation of sub-mJ terahertz pulses by optical rectification 总被引:1,自引:0,他引:1
Fülöp JA Pálfalvi L Klingebiel S Almási G Krausz F Karsch S Hebling J 《Optics letters》2012,37(4):557-559
Recent theoretical calculations predicted an order-of-magnitude increase in the efficiency of terahertz pulse generation by optical rectification in lithium niobate when 500 fs long pump pulses are used, rather than the commonly used ~100 fs pulses. Even by using longer than optimal pump pulses of 1.3 ps duration, 2.5× higher THz pulse energy (125 μJ) was measured with 2.5× higher pump-to-THz energy conversion efficiency (0.25%) than reported previously with shorter pulses. These results verify the advantage of longer pump pulses and support the expectation that mJ-level THz pulses will be available by cooling the crystal and using large pumped area. 相似文献
10.
11.
We present simulations for a design of a high-energy single-stage mid-IR difference frequency generation adapted to a two-color Ti:sapphire amplifier system. The optimized mixing process is based on chirped pulse difference frequency generation (CP-DFG), allowing for a higher conversion efficiency and reduced two-photon absorption losses. The numerical start-to-end simulations include stretching, chirped pulse difference frequency generation and pulse compression. Realistic design parameters for commercially available nonlinear crystals (GaSe, AgGaS2, LiInSe2, LiGaSe2) are considered. Compared with conventional unchirped DFG directly pumped by Ti:sapphire technology, we predict a threefold increase in the quantum efficiency. Our CP-DFG scheme provides up to 340 μJ pulse energy directly at 7.2 μm when pumped with 8 mJ and supports a bandwidth of up to 350 nm. The resulting 240 fs mid-IR pulses are inherently phase stable. 相似文献
12.
In ultrashort pulse amplification a narrowband gas pump pulse laser has been used for the first time. An all-stage optical parametric chirped pulse amplifier (OPCPA) was driven by a single-shot iodine photodissociation laser. For the first time a broadband amplification was achieved in potassium dihydrogen phosphate crystal at 800 nm seeding. Ti:sapphire laser pulses stretched from 12.5 fs to 250 ps were amplified and compressed to 27 fs at a 0.5 TW output power. The results suggest using narrowband high power gas lasers as OPCPA drivers to generate petawatt beams. 相似文献
13.
本文分析了小信号情况下飞秒脉冲的倍频特性,在非耗尽近似下,得出了飞秒脉冲二次谐波波形及效率的解析解,在时间域内,对一般条件的耦合波方程进行了数值解,分析了相位失配对飞秒脉冲倍频波形及效率的影响。 用0.5mm厚的一类匹配LBO晶体对碰撞锁模激光器产生的80fs超短脉冲进行了腔外倍频实验,实验结果与理论计算符合得很好。 相似文献
14.
S. Ališauskas V. Pyragait? V. Smilgevi?ius A. Stabinis A. Piskarskas 《Optics Communications》2010,283(3):469-12726
We demonstrate optical parametric amplification of broadband chirped pulses in BBO crystal pumped by several intersecting beams extracted from independent laser amplifiers. The energy of amplified signal ranged from 0.23 to 0.72 mJ depending on a number of pump beams used as well as pumping configuration employed. The conversion efficiency dependence on intersection angles of pump beams is revealed and modeling of interplay of interacting waves is presented. 相似文献
15.
Optical rectification of ultrashort near-IR laser pulses with tilted pulse fronts and pulse energies of a few J in Mg-doped stoichiometric LiNbO3 cooled to low temperature is a powerful technique for efficient generation of THz pulses. The pulse energy critically depends on the Mg doping (necessary for preventing photorefractive damage) and can be easily increased by a factor of three if the MgO content is reduced. Pulse energies up to 400 pJ at repetition rates of 200 kHz and 3.4% quantum conversion efficiency are achieved at 77 K. At 10 K, changing the tilt angle of the pump pulse front results in continuous tuning of the frequency across the 1.0–4.4 THz range. The temporal pulse shapes measured by electro-optic sampling are in good agreement with the signal calculated by a simple theory. This model predicts tunability on a considerably broader range and narrower spectra even at room temperature if GaSe is used instead of LiNbO3. The advantages of the velocity matching technique utilizing tilted pulse fronts are analyzed in comparison with quasi-phase-matching in periodically poled LiNbO3 crystals. The first method provides a ten times higher pulse energy conversion efficiency. PACS 42.65.Ky; 42.70.Mp; 42.72.Ai 相似文献
16.
In this article we propose a theoretical treatment of noncollinear phase-matched femtosecond parametric interaction process pumped by ultrashort optical pulses, and investigated the pulse characteristics of OPG in BBO crystal. The results show that the major factors, which affect the optical parametric conversion coefficient and durations of the pulses, are the group velocity mismatch and the phase mismatch among the three ultra-short pulses. In addition, the material dispersion can cause the durations of the pulses to increase when pump pulse is below 20 fs, and its influence becomes more obvious at low pump intensity. 相似文献
17.
18.
R. Andrew Sims Pankaj Kadwani Heike Ebendorff-Heideprem Lawrence Shah Tanya M. Monro Martin Richardson 《Applied physics. B, Lasers and optics》2013,111(2):299-304
We report femtosecond pulse generation and chirped pulse amplification in Tm:fiber. A mode-locked oscillator operating in the soliton regime produced 800 fs pulses with 5 nm spectral bandwidth, at 40 pJ pulse energy. This oscillator seeded a pre-amplifier that utilizes a Raman soliton self-frequency shift to produce wavelength tunable pulses with 3 nJ energy, reduced pulse duration of 150 fs, and increased bandwidth of 30 nm. For further amplification, the pulses were stretched up to 160 ps using a chirped Bragg grating (CBG). Stretched pulses were amplified to 85 nJ after compression in single-mode Tm:fiber and recompressed with the CBG as short as 400 fs. Compressed pulses were coupled into a highly nonlinear tellurite fiber to investigate the potential of this ultrashort pulse 2-μm fiber source as a pump for mid-IR supercontinuum generation. 相似文献
19.
A compact two-stage optical parametric chirped pulse amplifier based on photonic crystal fibre is demonstrated.A 1064-nm soliton pulse is obtained in a home-made photonic crystal fibre (PCF) with femtosecond pulse pumping and then amplified to 2 mJ in an Nd:YAG regenerative amplifier.After the amplified pulses pass through the LBO crystal,the 532-nm double-frequency light with an energy of 0.8 mJ and a duration of over 100 ps at 10-Hz repetition rate is generated as a pump source in the following two-stage optical parametric amplification (OPA).The 850-nm chirped signal light gain from the stretcher is 1.5×10 4 in the first-stage OPA while it is 120 in the second-stage OPA.The total signal gain of optical parametric chirped pulse amplification (OPCPA) can reach 1.8×10 6. 相似文献
20.
构建了掺镱大模场面积单偏振光子晶体光纤飞秒激光非线性放大系统. 讨论了腔内净色散量和抽运功率对振荡级输出参数的影响和振荡级参数对放大级输出参数的影响. 在本实验条件下, 当腔内净色散量取较大负色散时, 振荡级直接输出的脉冲更宽, 且携带更少的啁啾. 当振荡级抽运4.53 W时, 选择最接近变换极限的脉冲作为种子脉冲, 放大级在60 W抽运时输出压缩后无基底的短脉冲, 宽度为45.7 fs, 平均功率28 W. 振荡级抽运功率增加到5.08 W, 放大级抽运70 W时, 获得最高输出功率34.5 W, 对应脉宽53.5 fs. 相似文献