Periodically poled lithium niobate waveguide sum-frequency generator for efficient single-photon detection at communication wavelengths

We present a device to facilitate single-photon detection at communication wavelengths based on continuous-wave sum-frequency generation with an upconversion efficiency exceeding 90%. Sum-frequency generation in a periodically poled lithium niobate waveguide is used to upconvert signal photons to the near infrared, where detection can be performed efficiently by use of silicon avalanche photodiodes.     

Efficient single-photon counting at 1.55 microm by means of frequency upconversion

We demonstrate efficient single-photon detection at 1.55 microm by means of sum-frequency mixing with a strong pump at 1.064 microm in periodically poled lithium niobate followed by photon counting in the visible region. This scheme offers significant advantages over existing InGaAs photon counters: continuous-wave operation, higher detection efficiency, higher counting rates, and no afterpulsing. We achieved single-photon upconversion efficiency of 90% at 21.6 W of circulating power in a resonant pump cavity with a 400-mW Nd:YAG laser. We observed high background counts at strong circulating pump powers due to efficient upconversion of pump-induced fluorescence photons.     

Efficient and stable single-photon counting at 1.55 microm by intracavity frequency upconversion

A single-photon signal at 1.55 microm was converted to the visible region by sum-frequency mixing with a strong pumping beam at 1064 nm in a periodically poled lithium niobate crystal placed in a diode-pumped Nd:YVO4 laser cavity. As the intracavity pump laser could be automatically stabilized without cavity lock, robust long-term stability was demonstrated for single-photon frequency upconversion, with a conversion efficiency of 74.3%. Such a stable single-photon upconversion was demonstrated to be efficient and robust for single-photon counting at 1550 nm, and the corresponding background noise was measured at less than 420 x 10(3) s(-1).     

Single-photon detection and its applications

A single-photon detector is an extremely sensitive device capable of registering photons,offering essential technical support for optics quantum information applications.We review herein our recent experimental progress in the development and application of single-photon detection techniques.Techniques based on advanced self-differencing,low-pass filtering,frequency up-conversion and photon-number-resolving are introduced for attaining high-speed,high-efficiency,low-noise single-photon detection at infrared wavelengths.The advantages of high-speed single-photon detection are discussed in some applications,such as the laser ranging and quantum key distribution.The photon-number-resolving detection is shown to support efficient quantum random number generation.     

Time-resolved single-photon detection by femtosecond upconversion

We demonstrate a time-resolved single-photon detection technique based on ultrafast sum-frequency generation, providing femtosecond measurement capability for single photons in photonic quantum information processing. Noncollinear broadband upconversion in periodically poled MgO-doped stoichiometric lithium tantalate with an ultrafast pump and detection with a Si single-photon counter enable efficient detection of IR photons and temporal resolution of ~150 fs. We utilize the timing resolution to map the generation efficiency profile along the propagation axis of a periodically poled KTiOPO(4) crystal, revealing its local grating quality with millimeter resolution. We also apply the technique to two-photon coincidence measurements and directly demonstrate time anticorrelation between coincident-frequency entangled photons that are parametrically generated under extended phase-matching conditions.     

Cascaded frequency upconversion for high-speed single-photon detection at 1550 nm

We present a device for two-stage frequency upconversion of single-photon-level signals in the 1.55 μm telecom band to the green spectral region with low excess noise, suitable for detection by low-timing-jitter silicon single-photon avalanche photodiodes (APDs). We achieve a net conversion efficiency of 87% and a system timing jitter below 70 ps FWHM, dominated by the jitter of the APD. Modifications of our device are suitable for downconversion of single photons from visible-wavelength quantum emitters into the telecom band.     

1.5 microm photon-counting optical time-domain reflectometry with a single-photon detector based on upconversion in a periodically poled lithium niobate waveguide

Optical time-domain reflectometry (OTDR) is one of the most powerful tools in the characterization of optical fiber links. We demonstrate a photon-counting OTDR system at 1.5 microm with a single-photon detector, which combines frequency upconversion in a periodically poled lithium niobate waveguide and a silicon avalanche photodiode. The system exhibits high sensitivity, good spatial resolution, and short measurement time.     

Upconversion Spectrum of Tm-doped Fiber Pumped by Multiwavelengths from 760 nm to 810 nm

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The third-order optical nonlinearity and upconversion luminescence of CdTe quantum dots under femtosecond laser excitation

The aqueous CdTe quantum dots (QDs) were synthesized by the electrostatic reaction method. The optical properties of CdTe QDs were investigated by femtosecond Z-scan and time-resolved luminescence technique in nonresonant spectral region. The nonlinear absorption and refraction are ascribed to two-photon absorption, and time-resolved upconversion photoluminescence produces biexponential decay pattern at infrared femtosecond laser excitation. Upconversion luminescence is composed of a band-edge excitonic state and a photoinduced trapping state. The short-lived band-edge excitonic emission is independent of the detection wavelengths, and long-lived species becomes even longer with the increase of detection wavelengths, which indicates the size dependence of surface excitonic emission. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

NbN superconducting nanowire single photon detector with efficiency over 90% at 1550 nm wavelength operational at compact cryocooler temperature

The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an incident photon wavelength of 1550 nm is 93%. This performance was attained from a superconducting nanowire single-photon detector made of amorphous WSi; such detectors are usually operated at sub-Kelvin temperatures. In this study, we first demonstrate superconducting nanowire single-photon detectors made of polycrystalline NbN with system detection efficiency of 90.2% for 1550-nm-wavelength photons at 2.1 K, accessible with a compact cryocooler. The system detection efficiency saturated at 92.1% when the temperature was lowered to 1.8 K. We expect the results lighten the practical and high performance superconducting nanowire single-photon detectors to quantum information and other high-end applications.     

Ultrafast extreme ultraviolet holography: dynamic monitoring of surface deformation

We demonstrate femtosecond time-resolved dynamic Gabor holography using highly coherent extreme ultraviolet light generated by high harmonic upconversion of a femtosecond laser. By reflecting this light from an impulsively heated surface, we implement a simple and robust single-reflection geometry for phase-sensitive holographic detection at extreme UV wavelengths. Using this setup, we study the ultrafast deformation and subsequent acoustic oscillations within a thin metal film. These measurements exhibit subpicometer spatial sensitivity in the vertical dimension.     

Deterministic Secure Quantum Communication with Collective Detection Using Single Photons

Two novel single-photon deterministic secure quantum communication (DSQC) schemes with collective detection are proposed. One is a two-party DSQC, the other is a DSQC network. In these two schemes, only single-photon source and single-photon measurements are required, which makes the schemes more feasible with present techniques. Apart from this, a detection strategy called collective detection is utilized in our schemes, in which the detection is taken only once after the whole process of particle transmission. Such detection strategy improves the efficiencies of our protocols and also reduces the cost of realization as the message sender only need to perform unitary operations in the whole communication. What’s more, the efficiencies of qubits and source capacity are both high since almost all the states can be used to transmit message except the ones used for eavesdropping check and each single photon can carry one bit of information. Finally, we prove the security of the our protocols by using the theorems on quantum operation discrimination.     

Efficient and low-noise single-photon detection in 1550 nm communication band by frequency upconversion in periodically poled LiNbO3 waveguides

We demonstrate 1500 nm band single-photon detection with low dark-count noise and a potentially high efficiency, which may allow long distance and high-bit-rate quantum key distribution. By developing frequency upconversion devices based on periodically poled lithium niobate waveguides, which are specifically designed to use a pump wavelength longer than that of communication-band photons, we completely eliminate the dark-count noise caused by parasitic nonlinear processes in the waveguide. We observed an internal conversion efficiency as high as 40% and demonstrated scaling down to the single photon level while maintaining a background dark-count rate of 10(2)s(-1).     

Extended phase matching of high harmonics driven by mid-infrared light

We demonstrate that phase-matched frequency upconversion of ultrafast laser light can be extended to shorter wavelengths by using longer driving laser wavelengths. Experimentally, we show that the phase-matching cutoff for harmonic generation in argon increases from 45 to 100 eV when the driving laser wavelength is increased from 0.8 to 1.3 microm. Phase matching is also obtained at higher pressures using a longer-wavelength driving laser, mitigating the unfavorable scaling of the single-atom response. Theoretical calculations suggest that phase-matched high harmonic frequency upconversion driven by mid-infrared pulses could be extended to extremely high photon energies.     

高时间稳定性的雪崩光电二极管单光子探测器

雪崩光电二极管单光子探测器是一种具有超高灵敏度的光电探测器件,在远距离激光测距、激光成像和量子通信等领域有非常重要的应用.然而,由于雪崩光电二极管单光子探测器的雪崩点对工作温度高度敏感,因此在外场环境下工作时容易出现增益波动,继而导致单光子探测器输出信号的延时发生漂移,严重降低了探测器的时间稳定性.本文发展了一种稳定输出延时的方法,采用嵌入式系统控制雪崩光电二极管,使其处于恒定温度,并实时补偿由环境温度引起的延时漂移,实现了雪崩光电二极管单光子探测器的高时间稳定性探测.实验中,环境温度从16 ℃变化到36 ℃,雪崩光电二极管的工作温度稳定在15 ℃,经过延时补偿,雪崩光电二极管单光子探测器输出延时漂移小于±1 ps,时间稳定度达到0.15 ps@100 s.这项工作有望为全天候野外条件和空间极端条件下的高精度单光子探测应用提供有效的解决方法.     

Detection probability of single photons in a slant path atmospheric turbulence communication channel

Using Rytov approximation and modified von Karman spectrum model of the index-of-refraction, the detection probability of single-photon beam propagation in a atmospheric turbulence communication channel is investigated and developed. In this research, the single-photon beam is assumed as a pulse beam which has an initial Gaussian temporal shape of the pulse and a Laguerre-Gaussian fundamental-model spatial distribution. It is found that in order to obtain the messages probability greater than or equal 0.1, we should encode and dispatch 66680 photons in identical information carriers at the transmitting side, and the radius of the detector at the receiving plane must be at least up to 0.4 m when the photons propagate in a turbulent atmosphere communication channel.     

光极限探测技术在空间通信中的应用

光是人类最早的科学研究对象之一,光子是光的最小能量单元,具备量子的基本特征.随着科学技术发展,人类已经能够实现对单个光子的极限探测.光的常规探测已经普遍应用于地面光纤通信中,而光的极限探测则在空间量子通信及深空超远距离光通信中具备重要的应用价值.文章介绍了光极限探测技术在空间量子科学实验、空间光子通信中的典型应用及涉及...     

Single-Photon Detection at Telecom Wavelengths

A single-photon detector based on an InGaAs avalanche photodiode has been developed for use at telecom wavelengths. A suitable delay and sampling gate modulation circuit are used to prevent positive and negative transient pulses from influencing the detection of true photon induced avalanches. A monostable trigger circuit eliminates the influence of avalanche peak jitter, and a dead time modulation feedback control circuit decreases the afterpulsing. From performance tests we lind that at the optimum operation point, the quantum efficiency is 12% and the dark count rate 1.5 × 10^-6 ns^-1, with a detection rate of 500 kHz.     

在高于253 K温度下的1550 nm波长单光子探测实验

介绍了在高于253 K的温度下,实现红外单光子探测的实验.选用拉通电压较高的雪崩光电二极管（APD）,设计制作了非线性限流技术保护高温工作的APD,利用半导体热电制冷器,在256.8K的温度下,实现了1550 nm波段的单光子探测实验.单光子探测的暗记数率为3.13×10－5 ns,在220 kHz/s的单光子脉冲速率下,探测效率为2.08%.     

Properties of two-photon fluorescence and superradiance of a new organic dye C46H51N2B

Linear and nonlinear optical properties of a new organic dye, trans-4-[p-(N-n-butyl-N-n-butylamino)-styryl]-N-methyl-pyridinium tetraphenylborate solution in dimethyl formamide (DMF) have been studied systematically. When excited with mode-locked picosecond 1 064 nm laser beam, intense upconversion fluorescence and superradiance can be obtained. The temporal behaviors of one-photon absorption and two-photon absorption (TPA) fluorescence and superradiance have been studied. The highest upconversion efficiency was found to be 4.1% at a pump energy of 4 mJ. By using an optical parameter amplifier (OPA) as the pump laser, the nonlinear transmittance and upconversion efficiencies of the dye solution at different wavelengths were measured. The strongest linear absorption was found at a wavelength of 930 nm whereas the highest upconversion efficiency was at 1 030 nm. The 100 nm red-shift for the highest upconversion efficiency wavelength compared with the strongest nonlinear absorption are caused by excited state absorption. Received 17 October 2001 and Received in final form 21 December 2001