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1.
Efficient single-pass second-harmonic generation (SHG) of tunable high-repetition-rate picosecond pulses into the blue is reported in the nonlinear crystal BiB3O6. Using 2.4 ps fundamental pulses from a mode-locked Ti:sapphire laser at 76 MHz and a 10 mm crystal cut for type I (e + e --> o) phase matching in the optical yz plane, second-harmonic average powers as high as 990 mW with excellent stability have been generated at 52% conversion efficiency, and a tunable range of 370-450 nm is demonstrated. From measurements of single-pass SHG in the continuous-wave regime an effective nonlinear coefficient of 3.7 pm/V has been verified for BiB3O6, and direct comparison with beta-BaB2O4 confirms a SHG power enhancement of approximately 23% for the same crystal length. Autocorrelation measurements in a 200 microm crystal of beta-BaB2O4 result in durations of 2.8 ps for the second-harmonic blue pulses. 相似文献
2.
采用高温固相法通过掺杂不同种类的镧系元素以及改变掺杂元素的浓度制备了系列SrB_4O_7∶Re~(2+)(Re代表Ce,Nd,Gd和Lu)荧光材料,利用实验室自建的非偏振显微共聚焦荧光/拉曼测量系统重点研究了其荧光光谱特性。研究发现,SrB_4O_7∶Re~(2+)和SrB_4O_7∶Sm~(2+)具有相似的荧光特性,最强单峰对应~5 D_0-~7 F_0电子跃迁所产生的荧光峰(0-0峰),峰位为685.41nm;在700和730nm附近还对应有~5 D_0-~7 F_1和~5 D_0-~7 F_2电子跃迁所产生的两条强度较弱的荧光带;在相同条件下,SrB_4O_7∶Re~(2+)的0-0峰强度较SrB_4O_7∶Sm~(2+)的0-0峰强度至少要弱一个量级。对SrB_4O_7∶Re~(2+)荧光光谱分析结果显示,掺杂元素种类和掺杂元素浓度是影响荧光光谱强度的关键因素,两者直接决定了能参与发光的Re~(2+)离子的总量。 相似文献
3.
Soliton self-frequency shift (SSFS) in a photonic crystal fiber (PCF) pumped by a long-cavity mode-locked Cr:forsterite laser is integrated with second harmonic generation (SHG) in a nonlinear crystal to generate ultrashort light pulses tunable within the range of wavelengths from 680 to 1800?nm at a repetition rate of 20?MHz. The pulse width of the second harmonic output is tuned from 70 to 600?fs by varying the thickness of the nonlinear crystal, beam-focusing geometry, and the wavelength of the soliton PCF output. Wavelength-tunable pulses generated through a combination of SSFS and SHG are ideally suited for coherent Raman microspectroscopy at high repetition rates, as verified by experiments on synthetic diamond and polystyrene films. 相似文献
4.
本文基于有限元法研究了直立生长于GaAs衬底的GaAs纳米线的光场响应和光场增强性质. 实验使用多个波长的飞秒激光脉冲激发GaAs纳米线, 测得了较高效率的二次谐波信号, 并首次使用宽带超连续飞秒脉冲 (1000–1300 nm) 在纳米线上获取了宽带、无杂散荧光噪声的二次谐波信号. 这种高效的二次谐波产生过程主要归因于纳米结构引起的局域场增强效应. 本文阐明了GaAs纳米线的二次谐波倍频特性, 这些结果对于其在纳米光学中的光器件、 光集成等领域的进一步研究和实际应用具有很好的参考价值.
关键词:
GaAs纳米线
二次谐波
飞秒激光 相似文献
5.
6.
We present an effective design of aperiodically stacked layers of nonlinear material and air, sandwiched by two truncated photonic crystals, in terms of the simulation annealing method. The constructed structure can achieve multiple-wavelength second-harmonic generation (SHG) at the preassigned wavelengths. We derive a general solution of SHG in 1D inhomogeneous systems and apply it to evaluate the SHG conversion efficiency. Numerical simulations show that the conversion efficiency of SHG can be significantly enhanced when the fundamental wave frequencies are assigned to the designed defect states. 相似文献
7.
We report on the observation of quasi-phase matched collinear second harmonic generation (SHG) at 20 wavelengths in a two-dimensional nonlinear photonic quasi-crystal with decagonal lattice. We show that at some wavelengths the second harmonics are generated via standard quasi-phase matching, namely a reciprocal vector exists that equals the phase-mismatch vector, while at others the SHG is as a result of the projection-based quasi-phase matching in which the momentum conservation is satisfied up to a projection of a reciprocal vector onto the direction of propagation. In spite of different generation mechanisms, the reciprocal vectors (or their projections) involved in the collinear QPM SHG can be described by a generalized equation. 相似文献
8.
Achintya K. Bhowmik Shida Tan Ayayi C. Ahyi J.A. Dharmadhikari A.K. Dharmadhikari D. Mathur 《Optics Communications》2007,280(2):472-476
Single-crystal thin-film of an organic second-order nonlinear optical material, 4-aminobenzophenone (ABP), is used to measure the pulsewidth of a Ti-Sapphire laser producing 45 fs pulses at 1 kHz repetition rate, by the non-collinear second-harmonic generation (SHG) intensity autocorrelation technique. These films are suitable for measurements over a broad wavelength range, down to 780 nm, due to their wide optical transparency. The single-crystal film with thickness (3 μm) less than the coherence length requires no phase-matching for efficient broadband SHG. Pulse walk-off due to group-velocity mismatch (GVM) and temporal broadening of the pulses due to group-velocity dispersion (GVD) are found to be negligible. These effects have been estimated for pulse width down to few-cycle pulses (10 fs), and the analyses show that these films can be used to characterize such ultrashort optical pulses. 相似文献
9.
Both supercontinuum conical emission (SCCE) and blue-green conical emission (CE) by means of second harmonic generation (SHG) were observed alternately in a β-barium borate (BBO) crystal induced by femtosecond laser pulses with vertical polarization state. Three theoretical models were analyzed to interpret the angular beam of SCCE. The experimental conical angles with different wavelengths in BBO crystal and BK-7 glass can be explained well by nonlinear X-wave model and Cerenkov type phase matching model other than four-wave mixing (FWM) model. 相似文献
10.
We report a stable, high-power source of picosecond pulses in the near-infrared based on intracavity second harmonic generation (SHG) of a MgO:PPLN optical parametric oscillator synchronously pumped at 81 MHz by a mode-locked Yb-fiber laser. By exploiting the large spectral acceptance bandwidth for Type I (oo→e) SHG in β-BaB2O4 and a 5 mm crystal, we have generated picosecond pulses over 752-860 nm spectral range under minimal angle tuning, with as much as 3.5 W of output power at 778 nm and >2 W over 73% of the tuning range, in good beam quality with TEM00 spatial profile and M2<1.4. The SHG output pulses have durations of 15.2 ps, with a spectral bandwidth of ~3.4 nm at 784 nm. In addition, the oscillator simultaneously provides a signal power of >1 W over 1505-1721 nm (25 THz) and idler power >1.8 W over 2787-3630 nm (25 THz), corresponding to a total (signal plus idler) tuning range of 1059 nm. The SHG, signal, and idler output exhibit passive long-term power stability better than 1.6%, 1.3%, and 1.6% rms, respectively, over 14 h. 相似文献
11.
在室温下测量了在空气中灼烧掺杂Dy2O3的SrB3O7的发射光谱。观测到了由Dy^3 到Dy^2 氧化态的变化。经优化,当在空气中灼烧温度为650℃时为产生Dy^2 的最佳温度。在457.9nm的激发下测出了两个峰位分别位于550和660nm的宽发射带。我们认为这两个宽发射带是由Dy^2 离子由5d态向4f基态能级(^5I8)跃迁产生的。讨论了几个有益于在这种基质中还原Dy^3 离子的条件。为了实现Dy^3 离子的还原,我们还在Ar/H2(4%)气氛中制备了Dy2O3掺杂的SrB4O7比较了这种样品和在空气中所制备的样品的光学特性。本文还对标专SrB4O7还原性和稳定性的g-因子由Tm^2 的[E0(Tm^3 /Tm^2 =-2.3V]推导出Dy^2 的[E0(Dy^3 /Dy^2 )=-2.6V],但对这种还原过程的局限性尚未确定。 相似文献
12.
HUANG Feiran WEI Zhiyi YANG JieZHOU Jianyin YU Zhenxin 《Chinese Journal of Lasers》1997,6(4):337-341
PropertiesofLBOandGenerationofMode┐lockingBlueFemtosecondPulsesHUANGFeiranWEIZhiyiYANGJieZHOUJianyinYUZhenxin(StateKeyLabora... 相似文献
13.
The characteristics of the second harmonic generations (SHGs) in homogeneous and inhomogeneous systems are investigated. We
consider two kinds of structures: one is aperiodic optical superlattices (AOSs) with homogeneous linear susceptibility and
the modulated second-order nonlinear susceptibility; the second is linear and nonlinear susceptibilities both the system with
inhomogeneous. We derive a general solution of SHG for the AOS with finite lateral width and of SHG in considering the depletion
of the pump light power. We carry out the design of AOSs by using simulation annealing (SA) algorithm and show that the constructed
AOSs can implement multiple wavelength SHGs with identical effective nonlinear coefficient at the preassigned wavelengths
of incident light. We observe great enhancement of SHGs in the one-dimensional photonic crystals (PCs) with defects consisting
of multiple photonic quantum wells made of nonlinear material when the frequency of fundamental wave aims at one of the defect
states. We also propose an effective design approach of aperiodically stacked layers of nonlinear material and air in terms
of the SA method. The constructed structure can achieve multiple-wavelength SHGs at the preas-signed wavelengths.
相似文献
14.
V. Venkataramanan K. Noguchi M. Aono T. Suzuki 《Applied physics. B, Lasers and optics》2002,74(7-8):683-689
We describe the instrumentation related to the first observation of magnetization-induced enhancement of surface second-harmonic
generation (SHG) from the paramagnetic Si(111)-7×7 surfaces. A judicious choice of polarization and sample orientation enabled
us to isolate the magnetic-field-dependent tensor element of the nonlinear susceptibility. A conductive liquid-nitrogen system,
coupled to an ultrahigh-vacuum system that is immune to the high magnetic field of 10 T, cooled the sample to about 120 K.
A high extinction that is necessary to detect the magnetization-induced SHG (MSHG) was accomplished by minimizing stray optical
effects such as Faraday rotation, photoluminescence and thermal birefringence in all optical components, with extra care taken
for the UHV window. Consistent and stable operation of this sensitive measurement system permitted experiments involving MSHG
at multiple wavelengths and temperatures. Probing the magnetization-induced optical nonlinearity was validated by quenching
the surface states by oxidation of the surface layers. From MSHG measurements at two wavelengths resonant with different surface-state
transitions, we were able to suggest that the observed MSHG is proportional to the number of dangling bond states of Si(111)-7×7.
Received: 15 January 2002 / Published online: 2 May 2002 相似文献
15.
We examine the characteristics and limitations of GRENOUILLE, a simple and compact implementation of the second-harmonic-generation (SHG) frequency-resolved-optical-gating (FROG) technique. We show that it can be made to operate effectively over a relatively wide range of pulse lengths and wavelengths. We also describe procedures for its design and calibration, and we discuss the use of arbitrary nonlinear SHG crystals. PACS 42.65.-k; 42.65.ReAn erratum to this article can be found at 相似文献
16.
本文研究了铕激活氟硼酸锶荧光体合成的反应机理,确定了该荧光体生成的最佳反应条件。在高于730℃时焙烧SrCo3、SrF2、H3BO3、NH4F和EuCl3的混合物,主要得到SrF0.1B4O6.95:Eu产物,当焙烧温度低于730℃时,可能形成一种弱发光的SrB6O10:Eu产物,经过870-900℃第二次焙烧,可以使SrB6O10比较完全地转变为SrB4O7晶型,焙烧气氛对产物的发光强度有一定的影响,粒状活性炭的存在(也就是在CO+CO2气氛)对焙烧最为有利。本文还测定了激活剂铕最佳浓度是每摩尔基质0.01mole铕,当高于0.015mole时发生浓度猝灭现象。用X射线衍射法、热重分析法和Sr2+、F-离子化学分析等手段,测定了荧光体的化学组成,它的一般式可写为:(1-x)SrO·xSrF2·2B3O3·yEu 0.02≤x≤0.05 0.005≤y≤0.015 相似文献
17.
Increased temperature acceptance bandwidth in frequency-doubling process using two different crystals 总被引:2,自引:2,他引:0
The temperature acceptance bandwidth of second-harmonic generation(SHG) can be dramatically improved by using two different kinds of nonlinear crystals with opposite signs of temperature derivation of phase mismatch. We study two SHG processes for the existing 1064 and 1550 nm high-average-power lasers. The numerical results show that the temperature acceptance bandwidth for SHG at 1064 nm can be three to five times larger than that of traditional single-crystal design, and it is also larger than that of using temperature-insensitive yttrium calcium oxyborate crystal. Importantly, the proposed design is applicable to various wavelengths, which suggests its potential in high-average-power SHG applications. 相似文献
18.
19.
Generation of 15 W femtosecond laser pulse from a Kerr-lens mode-locked Yb:YAG thin-disk oscillator
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We demonstrated a robust power-scalable Kerr-lens mode-locked(KLM) operation based on a Yb:YAG thin-disk oscillator.15-W,272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium and a 2.5 mm hard aperture in the cavity.247-fs pulses with an average power of 11 W could also be obtained by using a 2.4 mm hard aperture.Based on this shorter pulse,high efficient second-harmonic generation(SHG) was performed with a 1.7-mm-long Li B3O5(LBO) crystal.The SHG laser power was up to 5 W with the power fluctuation RMS of 1% measured over one hour. 相似文献
20.
《中国光学快报(英文版)》2016,(5)
We experimentally study the combined nonlinear effects,including four-wave mixing,stimulated Raman scattering,soliton dynamics,and cross-phase modulation by coupling femtosecond pulses around 850 nm into the normal dispersion region near the zero-dispersion wavelength in the fundamental mode of a homemade silica photonic crystal fiber. The nonlinear optical dynamics at different stages are demonstrated,and the discrete ultraviolet(UV) to visible wavelengths widely separated from the pump wave are generated by the interaction of several nonlinear effects involved. The UV to visible wavelengths can be used as short pulse sources for multiphoton ionization,fluorescence spectroscopy,and biochemical imaging. 相似文献