GHz photon-number resolving detection with high detection efficiency and low noise by ultra-narrowband interference circuits

We demonstrate the photon-number resolution(PNR)capability of a 1.25 GHz gated InGaAs single-photon avalanche photodiode(APD)that is equipped with a simple,low-distortion ultra-narrowband interference circuit for the rejection of its background capacitive response.Through discriminating the avalanche current amplitude,we are able to resolve up to four detected photons in a single detection gate with a detection efficiency as high as 45%.The PNR capability is limited by the avalanche current saturation,and can be increased to five photons at a lower detection efficiency of 34%.The PNR capability,combined with high efficiency and low noise,will find applications in quantum information processing technique based on photonic qubits.

High photon detection efficiency InGaAs/InP single photon avalanche diode at 250 K

Planar semiconductor InGaAs/InP single photon avalanche diodes with high responsivity and low dark count rate are preferred single photon detectors in near-infrared communication.However,even with well-designed structures and well-con-trolled operational conditions,the performance of InGaAs/InP SPADs is limited by the inherent characteristics of avalanche pro-cess and the growth quality of InGaAs/InP materials.It is difficult to ensure high detection efficiency while the dark count rate is controlled within a certain range at present.In this paper,we fabricated a device with a thick InGaAs absorption region and an anti-reflection layer.The quantum efficiency of this device reaches 83.2%.We characterized the single-photon performance of the device by a quenching circuit consisting of parallel-balanced InGaAs/InP single photon detectors and single-period sinus-oidal pulse gating.The spike pulse caused by the capacitance effect of the device is eliminated by using the characteristics of parallel balanced common mode signal elimination,and the detection of small avalanche pulse amplitude signal is realized.The maximum detection efficiency is 55.4%with a dark count rate of 43.8 kHz and a noise equivalent power of 6.96×10^(−17 )W/Hz^(1/2) at 247 K.Compared with other reported detectors,this SPAD exhibits higher SPDE and lower noise-equivalent power at a higher cooling temperature.

Total dose test with γ-ray for silicon single photon avalanche diodes

Gamma-ray(γ-ray)radiation for silicon single photon avalanche diodes(Si SPADs)is evaluated,with total dose of 100 krad(Si)and dose rate of 50 rad(Si)/s by using 60Co as theγ-ray radiation source.The breakdown voltage,photocurrent,and gain have no obvious change after the radiation.However,both the leakage current and dark count rate increase by about one order of magnitude above the values before the radiation.Temperature-dependent current-voltage measurement results indicate that the traps caused by radiation function as generation and recombination centers.Both leakage current and dark count rate can be almost recovered after annealing at 200℃for about 2 hours,which verifies the radiation damage mechanics.

Numerical analysis of In_(0.53) Ga_(0.47) As/InP single photon avalanche diodes

A rigorous theoretical model for Ino.53Gao.47As/InP single photon avalanche diode is utilized to investigate the dependences of single photon quantum efficiency and dark count probability on structure and operation condition. In the model, low field impact ionizations in charge and absorption layers are allowed, while avalanche breakdown can occur only in the multiplication layer. The origin of dark counts is discussed and the results indicate that the dominant mechanism that gives rise to dark counts depends on both device structure and operating condition. When the multiplication layer is thicker than a critical thickness or the temperature is higher than a critical value, generation-recombination in the absorption layer is the dominative mechanism; otherwise band-to-band tunneling in the multiplication layer dominates the dark counts. The thicknesses of charge and multiplication layers greatly affect the dark count and the peak single photon quantum efficiency and increasing the multiplication layer width may reduce the dark count probability and increase the peak single photon quantum efficiency. However, when the multiplication layer width exceeds 1 μm, the peak single photon quantum efficiency increases slowly and it is finally saturated at the quantum efficiency of the single photon avalanche diodes.

One new photon avalanche phenomenon of Er^(3+) at 976 nm excitation

A photon avalanche phenomenon was observed in Er^3＋ and Li^ ＋ eodoped ZnO nanocrystals at room temperature under excitation around 976 nm. When the excitation power was over 120 mW/mm^2 , we found that the upconversion of red emission was generated by a four-photon absorption process and might be caused by intense interaction between neighboring Er^3 ＋ ions ： ^4 F7/2 ＋ ^4 I11/2 → 2^4 F9/2. When the excitation power was over the threshold of 240 mW/mm^2, the green emission avalanche upconversion was generated through an excitedstate absorption process ： ^4 F9/2 ＋ photon →^2 H9/2. The study extends the knowledge of this ion to a wider range of upconversion application.

基于迁移光子雪崩效应的单束低功率激光三维多色超分辨显微成像技术

The development of super-resolution fluorescence microscopy is very essential for understanding the physical and biological fundamentals at nanometer scale.However,to date most super-resolution modalities require either complicated/costly purpose-built systems such as multiple-beam architectures or complex post-processing procedures with intrinsic artifacts.Achieving three-dimensional(3D)or multi-channel sub-diffraction microscopic imaging using a simple method remains a challenging and struggling task.Herein,we proposed 3D highly-nonlinear super-resolution microscopy using a singlebeam excitation strategy,and the microscopy principle was modelled and studied based on the ultrahigh nonlinearity enabled by photon avalanches.According to the simulation,the point spread function of highly nonlinear microscopy is switchable among different modes and can shrink three-dimensionally to sub-diffraction scale at the photon avalanche mode.Experimentally,we demonstrated 3D optical nanoscopy assisted with huge optical nonlinearities in a simple laser scanning configuration,achieving a lateral resolution down to 58 nm(λ/14)and an axial resolution down to 185 nm(λ/5)with one single beam of low-power,continuous-wave,near-infrared laser.We further extended the photon avalanche effect to many other emitters to develop multi-color photon avalanching nanoprobes based on migrating photon avalanche mechanism,which enables us to implement single-beam dual-color sub-diffraction super-resolution microscopic imaging.

Determination of breakdown voltage of In_(0.53)Ga_(0.47)As/InP single photon avalanche diodes

We examine the saturation of relative current gain of Ino.53Gao.47As/InP single photon avalanche diodes （SPADs） operated in Geiger mode. The punch-through voltage and breakdown voltage of the SPADs can be measured using a simple and accurate method. The analysis method is temperature-independent and can be applied to most SPADs.

Effect of Zn^(2+) dopant on photon avalanche upconversion behavior of BiOCl:Er^(3+) crystals

Effect of divalent dopants, Zn2＋ ion, on the high-order photon avalanche （PA） upconversion （UC） emission of Er3＋ doped BiOCl microcrystals was investigated. XRD results indicated that Zn2＋ ion dopants would mostly enter into the lattice space at low and moderate doping concentration, and began to substitute Bi3＋ ion gradually at heavily doping level. Under exaction at 980 nm, the PA UC of violet, green and red emission of Er3＋ ions could be observed, and the UC emission intensity increased with increasing the Zn2＋ addition below 8 mol.%, then decreased with further addition. Power dependence study showed that the dopant concentration of Zn2＋ had no obviously negative effect on the occurrence of PA emission. On the bases of results investigated herein, we considered that the lattice distortion by Zn2＋ doping could not directly change the special PA emission of BiOCI：Er3＋, but would improve the emission intensity when used as lattice modifier.