共查询到20条相似文献,搜索用时 93 毫秒
1.
It is shown that random duty-cycle errors in quasi-phase-matching (QPM) nonlinear optical devices enhance the efficiency of processes far from the QPM peak. An analytical theory is shown to agree well with numerical solutions of second-harmonic generation (SHG) in disordered QPM gratings. The measured efficiency of 1550?nm band SHG in a periodically poled lithium niobate (PPLN) waveguide away from the QPM peak agrees with observations of domain disorder in a PPLN wafer by Zygo interferometry. If suppression of parasitic nonlinear interactions is important in a specific application of QPM devices, control of random duty-cycle errors is critical. 相似文献
2.
理论研究了周期极化铌酸锂晶体中通过自发参量下转换产生的纠缠双光子的波长管理方法.简并自发参量下转换产生的单色偏振纠缠双光子的波长,可以通过调整晶体的极化周期或工作温度自由地调节,特别是在加工好的晶体中极化周期是确定的,因而调整晶体的工作温度更加便捷.对于双色偏振纠缠双光子来说,不需改变入射的泵浦光以及晶体的极化结构,仅通过调节晶体的工作温度就可以实现o光光子和e光光子波长的严格交换. 相似文献
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O. Prakash H.-H. Lim B.-J. Kim K. Pandiyan M. Cha B. K. Rhee 《Applied physics. B, Lasers and optics》2008,92(4):535-541
Collinear broadband optical parametric generation (OPG) using periodically poled lithium niobate (PPLN) crystals were designed
and experimentally demonstrated with the quasi-phase matching (QPM) periods of 21.5, 24.0, and 27.0 μm. The broad gain bandwidth was accomplished by choosing a specific set of the period and the pump wavelength that allows
the group velocities of the signal and the idler to match close to the degeneracy point. OPG gain bandwidth and also the spectral
region could be controlled by proper design of QPM period and pump wavelength. The total OPG gain bandwidth of 600, 900, and
1200 nm was observed for the PPLN devices with QPM periods of 21.5, 24.0, and 27.0 μm, respectively. We have also observed multiple color visible generation whenever the OPG spectrum was significantly broad.
From the visible peaks of the three PPLN samples, it is found that broad gain bandwidth is crucial in the temperature-insensitive
collinear simultaneous RGB generation from a single crystal. 相似文献
5.
Zhensong Cao Xiaoming Gao Weidong Chen Huan Wang Weijun Zhang Zhiben Gong 《Optics and Lasers in Engineering》2009,47(5):589-593
The temperature tuning characteristics of quasi-phase matching (QPM) wavelength acceptance bandwidth in a uniform periodically poled lithium niobate (PPLN) based on difference-frequency generation (DFG) are studied theoretically and experimentally. This paper proposes a PPLN device consisting of several segments of different temperatures to obtain a more desirable performance for the QPM-DFG. The result shows that through the tuning of temperature, the bandwidth can be changed considerably and the method was proved suitable and accurate to calculate QPM wavelength acceptance bandwidth of DFG in a uniform PPLN crystal for temperatures between room temperature and 180 °C and mid-infrared (mid-IR) wavelengths ranging from 2.8 to 4.8 μm. 相似文献
6.
A wide tuning technique for mid-IR difference-frequency generation (DFG) with uniform grating periodically poled LiNbO(3) (PPLN) is presented. Based on the dispersion property of the PPLN, the quasi-phase matching (QPM) band for the pump can evolve to two separate bands, and the spacing between them can be increased with the decrease of the crystal temperature. Two such separate QPM bands can be used for increasing the idler tuning range when the crystal temperature is set to adapt the pump tuning. With the technique, an idler tuning range of 690nm is experimentally achieved with fiber laser fundamental lights. 相似文献
7.
基于周期极化晶体的Sellmeier方程和准相位匹配理论,对准相位匹配光参变振荡器的调谐特性进行了理论分析.通过数值模拟计算,得到了PPRTA晶体光参变振荡的调谐特性与极化反转光栅周期、晶体温度和抽运光波长等参量的关系曲线.并且与PPKTP晶体和PPLN晶体光参变振荡器的调谐特性进行了比较,研究了三者的不同之处,得出了PPRTA晶体的参量调谐特性优于PPKTP晶体和PPLN晶体的结论,与国外已报道的实验数据相吻合.证实了PPRTA晶体是一种可以产生可调谐近中红外光的理想准相位匹配非线性光学晶体. 相似文献
8.
We investigated angular tuning of quasi-phase-matching (QPM) second-harmonic generation (SHG), in order to extend the tunable range of QPM and to combine the advantages of QPM and birefringence phase-matching. The direction of the input fundamental wave vector was detuned from the QPM grating vector along the crystallographic Z-axis of a periodically-poled lithium niobate (PPLN) crystal in the XY- and XZ-planes. A?larger tuning range of SHG was obtained for the detuning in the XZ-plane, continuously shifting the QPM peak of the fundamental wavelength from 1524 to 1595?nm by changing the detuning angle from 0° (parallel to X-axis as conventional QPM) to 23.2°. 相似文献
9.
Widely tunable difference frequency generation around 3.4 μm using index dispersion property of PPLN
In this paper, the wide difference frequency generation (DFG) tuning characteristics around 3.4 μm are investigated by using
the index dispersion property of PPLN. With a ytterbium doped fiber laser (YDFL) and an erbium doped fiber laser (EDFL) as
the fundamental light sources, our simulation results show that the quasi-phase matching (QPM) wavelength acceptance bandwidth
(BW) for the pump is much larger than that for the signal. Although the positions of the broadened QPM pump bands vary with
the poling period and the signal wavelength, the corresponding idler tuning ranges center around 3.4 μm. With a signal wavelength
of 1.57 μm, an idler tuning range of greater than 170 nm is experimentally obtained in the 30 uniform grating PPLN. When the
signal wavelength and the poling period are respectively changed to 1.55 and 29.50 μm, wide DFG tuning operations around 3.4
μm are also achieved with the crystal temperature adjusted to adapt the change. 相似文献
10.
Third-harmonic generation (THG) in the cw regime from C-band radiation was achieved in annealed proton-exchanged periodically poled lithium niobate (PPLN) waveguides. By suitable design of fabrication parameters and operating conditions, quasi-phase-matching (QPM) is obtained simultaneously for the second-harmonic generation process (omega-->2omega, first-order QPM) and for the sum-frequency-generation process (omega+2omega-->3omega, third-order QPM), which provides the third harmonic of the pump field. The high overlap between the field profiles of the interacting modes--TM00 at omega and TM10 at 2omega and 3omega--results in what is believed to be the highest ever reported normalized conversion efficiency for THG from telecommunication wavelengths, equal to 0.72%W(-2) cm(-4). 相似文献
11.
Weirui Dang Yuping Chen Mingjun Gong Xianfeng Chen 《Applied physics. B, Lasers and optics》2013,110(4):477-482
In this paper, we have studied the characteristics of second-order nonlinear interactions with band-overlapped type-I quasi-phase-matching (QPM) second harmonic generation (SHG) and sum-frequency generation (SFG), and predicted a blue-shift with a band-narrowing of their bands and a sunken response in the SFG curve, which are due to the phase-matching-dependent competition between band-overlapped SHG and SFG processes. This prediction is then verified by the experiment in an 18-mm-long bulk MgO-doped periodically poled lithium niobate crystal (MgO:PPLN) and may provide the candidate solution to output controlling for flexible broadcast wavelength conversion, channel-selective wavelength conversion and all-optical logic gates by cascaded QPM second-order nonlinear processes. 相似文献
12.
The improvement of cascaded second-order nonlinearity ≤(2) : ≤(2) effects in a quasiphase-matching (QPM) structure constituted by a periodically poled lithium niobate (PPLN) waveguide is obtained utilizing an integrated metal mirror placed after an additional waveguide segment. The resulting double-pass device, which can be employed for wavelength conversion, is refined by choosing the most advantageous length of the segment waveguide and by taking into account both the thermal and electro-optic effects. In the ideal case of perfect QPM, for a grating length z G4 = 25 mm, the calculated double-pass maximum efficiency is eta dp = 22.86 dB, which is almost the triple of eta sp = 8.20 dB, calculated for the single-pass version (without mirror) for the same value of the pump and signal powers. 相似文献
13.
An electric-field poling process was established that yielded uniform periodically poled lithium niobate (PPLN) in 0.5 mm
thick lithium niobate substrate. We have fabricated 50 mm long fanned as well as multigrating PPLNs having period variations
from 25 μm to 32 μm. These PPLNs are required for quasi-phase-matched (QPM) optical parametric oscillator (OPO) applications.
We have also configured a bench-top OPO set-up based on these PPLNs. 相似文献
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J. H. Chang Q. H. Mao S. J. Feng J. Jiang X. L. Li Y. Y. Tian C. Q. Xu W. Q. Liu 《Applied physics. B, Lasers and optics》2011,104(4):851-859
The tuning properties for the mid-IR DFG laser based on uniform grating PPLN have been investigated with tunable YDFL and
EDFL fundamental lights. Our results show that, for a fixed crystal temperature, the idler tunable range is less than 10 nm
when the EDFL is tuned. Although the pump may be allowed to be tuned in its two QPM acceptance bands, the idler tunable range
is still narrow for a fixed temperature. By optimizing the crystal temperature, however, the two pump QPM acceptance bands
may be overlapped to form one broadband QPM band, which may be used to increase the idler tunable range to 175 nm near 3.4 μm
region. The positions of the single signal and the two separate pump QPM acceptance bands can be continuously moved by adjusting
the temperature, which may also be used for enhancing the idler tuning range. By tuning the EDFL while adjusting the temperature,
a whole combined idler tuning range between 2.98 and 3.78 μm was experimentally obtained with three fixed pump wavelengths
of 1.05, 1.08 and 1.11 μm. By tuning the YDFL in the two separate QPM acceptance bands, a tuning range of 690 nm has been
demonstrated with only one fixed signal wavelength of 1.58 μm. 相似文献
17.
We report the experimental demonstration of all-optical format conversion by exploiting the cascaded second-harmonic generation and difference-frequency generation (cSHG/DFG) in a periodically poled lithium niobate (PPLN) waveguide assisted by the reflective semiconductor optical amplifier (RSOA)-based active mode-locking. 10 and 20 Gbit/s format conversions from non-return-to-zero (NRZ) to return-to-zero (RZ) are successfully observed. Two schemes with either the NRZ signal or the pump optical clock set at the quasi-phase matching (QPM) wavelength are both verified in the experiment. 相似文献
18.
Tieli Zhang Jianquan Yao Xueyu Zhu Baigang Zhang Enbang Li Pu Zhao Haifeng Li Feng Ji Peng Wang 《Optics Communications》2007,272(1):111-115
This paper reports on a high-repetition-rate dual signal-wave (DSW) optical parametric oscillator (OPO) operating at the 1.5 μm band with tunable wavelength intervals from 2.5 nm to 69.1 nm. Two periodically poled crystals, a periodically poled lithium niobate (PPLN) with multiple gratings and a single grating MgO-doped PPLN (PPMgOLN), are cascaded in the same OPO cavity to generate dual signal-waves by using quasi-phase-matched (QPM) technique. The pump source was a Q-switched diode-pumped Nd:YVO4 laser operating at 50 kHz. At an incident pump power of 3 W, an average output power of 169.6 mW at 1489.2 nm and 1558.3 nm has been achieved. 相似文献
19.
S. Vasilyev H.-E. Gollnick A. Nevsky A. Grisard E. Lallier B. Gérard J. Jimenez S. Schiller 《Applied physics. B, Lasers and optics》2010,100(4):737-747
The effects of coupling between clockwise and counterclockwise modes in ring resonators due to back reflections from QPM gratings
in nonlinear crystals are investigated. We demonstrate, using simulations, that the non-phase-matched back reflection due
to typical imperfections of the QPM grating has a relevant magnitude and can give rise to the coupling. We developed an analytical
model and evaluated parameters of a singly resonant OPO in the presence of this coupling, which indicates that the threshold
pump power is doubled in the limit of strong coupling. We also evaluated the effect of the coupling with respect to resonant
power enhancement for cavity-enhanced nonlinear frequency mixing applications, finding that the enhancement is reduced by
up to a factor four. Experimental observations based on PPLN and orientation-patterned GaAs crystals and model predictions
are in good agreement. We propose and demonstrate a method for active stabilization of ring resonators with mode coupling
that relies on the dissimilarity of the coupled forward and backward modes. 相似文献
20.
基于周期极化反转铌酸锂(PPLN)光波导级联倍频和差频(SHG+DFG)的二阶非线性效应,提出并实验研究了皮秒脉冲的可调谐波长转换以及单信道到双信道的波长转换.信号光采用重复频率为40 GHz,脉宽为1.57 ps的脉冲信号.连续抽运光由光纤环形腔激光器(FRL)提供.不同于传统的SHG+DFG型波长转换,信号光固定在PPLN光波导倍频过程的准相位匹配(QPM)波长处,通过调节抽运光的波长实现了转换空闲光的可调谐输出.当使用两个抽运光时实验观察到了单信道到双信道的波长转换. 相似文献