Quantum frequency down-conversion of single photons at 1552 nm from single InAs quantum dot

Near-infrared single photon sources in telecommunication bands, especially at 1550 nm, are required for long-distance quantum communication. Here a down-conversion quantum interface is implemented, where the single photons emitted from single In As quantum dot at 864 nm is down converted to 1552 nm by using a fiber-coupled periodically poled lithium niobate（PPLN） waveguide and a 1.95 μmm pump laser, and the frequency conversion efficiency is ~40%. The singlephoton purity of quantum dot emission is preserved during the down-conversion process, i.e., g^（（2））（0）, only 0.22 at 1552 nm.This present technique advances the Ⅲ-Ⅴ semiconductor quantum dots as a promising platform for long-distance quantum communication.

Nonreciprocal Single Photon Frequency Conversion via Chiral Coupling between a V-Type System and a Pair of Waveguides

The single photon frequency conversion is investigated theoretically in the system composed of a V-type system chiral coupling to a pair of waveguides. The single photon scattering amplitudes are obtained using the real-space Hamiltonian. The calculated results show that the probability of single photon frequency down-or up-conversion can reach a unit by choosing appropriate parameters in the non-dissipative system with perfect chiral coupling.We present a nonreciprocal single photon beam splitter whose frequency of the output photon is different from that of the input photon. The influences of dissipations and non-perfect chiral coupling on the single frequency conversion are also shown. Our results may be useful in designing quantum devices at the single-photon level.

Six-bit all-optical quantization using photonic crystal fiber with soliton self-frequency shift and pre-chirp spectral compression techniques

In this paper, we propose an optical quantization scheme for all-optical analog-to-digital conversion that facilitates photonics integration. A segment of 10-m photonic crystal fiber with a high nonlinear coefficient of 62.8 W-1/kin is utilized to realize large scale soliton self-frequency shift relevant to the power of the sampled optical signal. Furthermore, a 100-m dispersion-increasing fiber is used as the spectral compression module for further resolution enhancement. Simulation results show that 317-nm maximum wavelength shift is realized with 1550-nm initial wavelength and 6-bit quantization resolution is obtained with a subsequent spectral compression process.

Optimizational 6-bit all-optical quantization with soliton self-frequency shift and pre-chirp spectral compression techniques based on photonic crystal fiber

In this paper, we optimize a proposed all-optical quantization scheme based on soliton self-frequency shift(SSFS)and pre-chirp spectral compression techniques. A 10m-long high-nonlinear photonic crystal fiber(PCF) is used as an SSFS medium relevant to the power of the sampled optical pulses. Furthermore, a 10m-long dispersion flattened hybrid cladding hexagonal-octagonal PCF(6/8-PCF) is utilized as a spectral compression medium to further enhance the resolution. Simulation results show that 6-bit quantization resolution is still obtained when a 100m-long dispersion-increasing fiber(DIF)is replaced by a 6/8-PCF in spectral compression module.

Inverse-designed photonic fibers and metasurfaces for nonlinear frequency conversion[Invited]

Typically, photonic waveguides designed for nonlinear frequency conversion rely on intuitive and established principles, including index guiding and bandgap engineering, and are based on simple shapes with high degrees of symmetry. We show that recently developed inverse-design techniques can be applied to discover new kinds of microstructured fibers and metasurfaces designed to achieve large nonlinear frequency-conversion efficiencies. As a proof of principle, we demonstrate complex, wavelength-scale chalcogenide glass fibers and gallium phosphide three-dimensional metasurfaces exhibiting some of the largest nonlinear conversion efficiencies predicted thus far,e.g., lowering the power requirement for third-harmonic generation by 104 and enhancing second-harmonic generation conversion efficiency by 107. Such enhancements arise because, in addition to enabling a great degree of tunability in the choice of design wavelengths, these optimization tools ensure both frequency-and phase-matching in addition to large nonlinear overlap factors.

Ultraviolet to visible frequency-conversion properties of rare earths doped glass ceramics

Nd3＋,Eu3＋ and Tb3＋ ions doped transparent chlorophosphate glass ceramics were prepared and their frequency-conversion properties were studied. X-ray diffraction （XRD） patterns evidenced the formation of expected halide nanocrystals. The absorption,excitation and emission spectra investigation indicated that some of rare earth （RE） ions were trapped in low phonon energy halide nanocrystals,and therefore an efficient down frequency-conversion was observed. The comparative spectroscopic studies of RE doped samples suggested that the glass ceramics systems are potentially applicable as efficient ultraviolet to visible frequency-conversion photonics materials.

用于铯原子里德伯态激发的509nm波长脉冲激光系统

介绍了一种用于里德伯原子激发的纳秒脉冲激光系统.实验利用两个kHz线宽的1018 nm连续激光器作为种子源,通过两个20GHz带宽的光纤调制器产生时间分离的脉冲激光;脉冲激光经掺镱光纤放大器后输出峰值功率约4600 W,单次穿过PPLN(周期极化铌酸锂)晶体倍频获得509 nm脉冲激光,典型脉冲激光峰值功率约173W.该激光系统单路输出脉冲重复频率在300 kHz-100 MHz范围连续可调,脉宽在1-100 ns范围连续可调.该509 nm激光在聚焦条件下可以实现GHz带宽的铯原子里德伯态激发.

基于频率纠缠源的高精度时间同步技术进展

为了进一步提高测绘导航领域的时间同步精度,研究论述可以突破标准量子极限的量子时间同步技术:概述频率纠缠源制备技术以及单光子探测技术的研究现状;并重点介绍基于不同量子时间同步协议的时间同步方案研究进展;最后对基于频率纠缠源的时间同步技术的发展趋势及其在测绘导航领域的潜在应用进行分析与展望。

Experiment study of wavelength conversion in a dispersion-flattened photonic crystal fiber

Wavelength conversion based on four-wave mixing （FWM） has been demonstrated using a 40-m dispersion flattened highly nonlinear photonic crystal fiber （HNL-PCF）. A conversion efficiency of -26 dB for a pump power of 19.5 dBm and a conversion bandwidth of 28 nm have been obtained, which are limited by the continuous wave （CW） laser wavelength range and tunability of optical band pass filters （OBPFs）.

面向雷达应用的微波光子处理技术

微波光子处理技术的核心思想是利用微波和光子学的融合,通过在光学域中对微波信号进行调制、传输和解调,实现对雷达信号的高效处理。这一技术的独特之处在于它能够克服传统雷达系统在处理高频宽带信号时所面临的一系列挑战,同时为系统提供了更大的灵活性和性能潜力。基于此,分析雷达应用的微波光子处理技术,探讨其未来可能的发展方向,更好地把握其在提升雷达系统性能、拓展应用领域方面的潜在机遇。

基于强度-相位级联调制的微波光子下变频法

为了优化微波光子下变频的无杂散动态范围,结合带反馈控制的强度调制器和相位调制器,提出并验证了基于强度和相位级联调制的微波光子下变频方法。通过理论推导和仿真分析了下变频原理以及本振功率对系统性能的影响,搭建了强度-相位级联调制的微波光子下变频系统,利用自行研制的直流偏置反馈控制模块确保强度调制器的工作状态稳定,对系统进行了性能测试。实验结果表明,增益和无杂散动态范围分别为-6.65dB和108.62dB/Hz^(2/3),与传统的强度调制器级联下变频链路相比,增益和无杂散动态范围分别提高了3.56dB和19.87dB。基于强度和相位级联调制的下变频方法仅需要单个偏置电压,且可通过反馈模块实现工作状态的稳定控制,系统结构简单、性能稳定,可实现大动态范围的微波光子下变频。

双光子荧光染料DPSSPI的合成与光学性质

合成了一种新型有机染料,反式,反式-4-{4-[4-(N,N-二苯胺基)苯乙烯基]苯乙烯基}-N-甲基吡啶碘盐(简称为DPSSPI)。用X射线衍射方法测定了DPSSPI的晶体结构,其单晶属于单斜晶系,P21/c空间群,结构分析表明分子骨架具有优良的平面性。溶剂对DPSSPI的光物理性质影响很大,研究发现在氯仿中显示出强的红色荧光发射。在1 064 nm的ps脉冲激光的激发下,DPSSPI的氯仿溶液还可以发出776 nm的双光子频率上转换荧光。

基于光子晶体光纤和飞秒激光源的近红外波段宽带孤子和可见区高效色散波产生的实验

将钛宝石激光器产生的飞秒激光脉冲泵浦实验室自制的高非线性双折射光子晶体光纤,脉冲的中心波长为820 nm,位于光子晶体光纤的接近于零色散的反常色散区.实验结果表明:随着泵浦功率的增加,一阶孤子的中心波长发生了红移,同时产生的色散波的中心波长则发生蓝移进入可见光区.当泵浦功率达到0.45 W时,色散波与残余泵浦的输出功率比为42.67,色散波的带宽达到81 nm,而处于近红外波段的红移孤子带宽可达231 nm.利用高非线性光子晶体光纤产生近红外波段宽带孤子和可见区高效色敬波的实验对飞秒激光频率转换和光谱展宽具有很好的借鉴意义.

基于双光频梳的多频段变频方法

为了探寻一种基于光频梳的灵活、高效的多频段变频方案,采用一个双驱动马赫-曾德尔调制器(D-MZM)和两个双平行马赫-曾德尔调制器(DP-MZM)组成的系统,由接收到的射频信号驱动D-MZM,进行单边带调制,进而得到一个载波和+1阶边带。利用两个DP-MZM分别作为两个光频梳产生器,产生两个相位相干、中心频率不同的光频梳,并进行了理论分析和实验验证;同时还研究了直流偏置点漂移对系统变频效率的影响。结果表明,所提出的变频系统,可将Ku波段的15GHz微波信号转化成3GHz,7GHz,11GHz,19GHz,23GHz和27GHz的信号;输出的微波信号信噪比可达28.82d B^29.99d B;直流偏置点的漂移量在-10%~50%范围内影响明显。该方法可为卫星通信系统提供多频段变频功能,从而满足多频段通信需求。

面向卫星载荷的大瞬时带宽微波光子信道化接收变频技术研究进展

随着卫星通信技术的飞速发展,以及卫星多功能融合技术的需求,未来卫星通信正朝着多频段、大带宽、多波束、配置灵活的方向发展。目前广泛应用于各个领域的卫星通信射频前端,主要采用传统的微波技术进行微波信号的信道化接收变频,带宽限制在GHz以下,无法满足大瞬时带宽信道化接收变频需求。将微波光子技术引入卫星通信射频前端可有效突破电域信道化接收变频技术瓶颈,简化射频前端的系统架构,提高卫星载荷性能。本文首先介绍了星载微波光子信道化接收变频技术的特点及基本结构。接着分类介绍了微波光子信道化接收变频的工作原理、主要实现方法及研究进展,最后给出大瞬时带宽微波光子信道化变频技术发展趋势及应用前景,为大瞬时带宽微波光子信道化接收变频设计及应用提供技术支撑。

双零色散光子晶体光纤中可见及红外宽带高效色散波

利用Ti宝石激光器生成的飞秒激光脉冲入射高非线性双零色散光子晶体光纤,进行非线性光谱实验.抽运脉冲的中心波长为800nm,位于接近零色散点的反常色散区,在正常色散区观测到双零色散光子晶体光纤产生的超宽带连续光谱输出,相对于单零色散光子晶体光纤,转换效率更高、谱带稳定而平滑,不仅获得了高效宽带蓝移色散波,还获得了长波段正常色散区的宽带红移色散波.实验结果与理论分析的相位匹配条件一致,阐明了色散波产生的物理机理.随泵浦功率的增大,长波段红移色散波发生明显红移,可见波段蓝移色散波强度显著增长,当泵浦功率为0.68 W时,泵浦光几乎全部转化,蓝移色散波与残余泵浦的输出功率之比大于257∶1,光谱转换效率极高,达到99.6%以上.蓝移色散波的宽带达到了309nm,近红外波段的红移色散波与孤子波相连,形成超连续谱,带宽可达628nm.实验结果对超短脉冲激光频率转换和宽带光源的研究具有参考价值.

基于串行MZM调制的微波光子变频性能分析与仿真

文章介绍了微波光子频率变换技术特点、应用背景和发展现状。在基于外调制的微波光子频率变换技术基础上,提出了光本振信号产生与变频一体的串行MZM调制微波光子变频方法,建立了基于串行MZM调制的微波光子变频数学仿真模型,对光本振信号射频功率、光本振模块调制指数、光电变频器调制指数、变频输出信号等进行了仿真与分析,分析与仿真结果为串行MZM调制的微波光子变频方案设计与应用提供了必要的理论依据和技术支撑。

无光滤波器的多频段微波信号产生方法

为多频带通信系统提供了一种基于无滤光器,单一光频梳的简单、灵活、稳定的多频段微波信号产生方案。在该系统中,双驱动马赫曾德尔调制器(DDMZM)是用来提供单边带信号,双平行马赫曾德尔调制器(DPMZM)当作一个光学滤波器使用。仿真结果表明,单一频率可以同时转换成为覆盖不同频段的几个频率。例如,C波段4. 3 GHz的频率可以转换至C、X、K波段中; X波段9. 2 GHz的频率可以被转化为S、C、K、Ka波段中。另外,为测试该系统的稳定性,我们对直流偏置点的漂移进行了研究。结果表明,该系统可以有效适应直流偏置点的漂移,并保持良好的转换效果。

高增益的微波光子变频智能控制方法

针对当前微波光子变频控制方法中存在的信号增益及动态范围较小等问题,提出基于级联强制信号调制器的高增益微波光子变频智能控制方法。深入分析变频处理后所得中频信号中存在的三阶交调失真情况,在此基础上,通过调节光电探测器的响应度、光载波信号的输出功率以及调制器输入信号的振幅来抑制变频信号的三阶交调,分析不同偏置相移与本振信号功率的关系,对比微波光子变频控制方法优化前后情况,得出优化后的微波光子变频智能控制方法的三阶交调抑制效果更好。实验结果表明,高增益微波光子变频智能控制方法能够有效完成信号变频控制,且其三阶交调抑制效果更好,能够为实践应用提供一定的理论依据。

光子晶体光学频率变换技术

文章首先介绍了光子晶体光学频率变换技术的基本原理和技术特点;然后简述光子晶体光学频率变换技术研究进展情况;最后指出了光子晶体变频技术在可调谐激光器和其它领域中的应用前景。