Photons in the Non－uniform Optical Waveguide Propagate along z－axis in Spiral Form

This paper gives the strict solution of optical field equation in the optical waveguides with parabolic profiles. It shows that the photons in the non-uniform optical waveguide propagate along z-axis in spiral form, just like a charged particles moving in the magnetic field. Only in the step-index waveguides, it can the photons propagate in ziging form.

One-Step Generation of Scalable Multiparticle Entanglement for Hot Ions Driven by a Standing-Wave Laser

An alternative scheme is proposed for one-step generation of multiparticle cluster state with trapped ionsin thermal motion.In this scheme,the ions are simultaneously illuminated by a standing-wave laser tuned to the carrier.During the operations,the vibrational mode is virtually excited,thus the quantum operations are insensitive to theheating.It is shown that the high fidelity multiparticle entanglement could be generated in just one step even includingthe small fluctuations of parameters.In addition,the ion does not need to be exactly positioned at the node of thestanding wave,which is also important from the viewpoint of experiment.

Tunneling of Spinor Bose-Einstein Condensates in Optical Lattice

In this letter, we have studied the tunneling effects and fluctuations of spinor Bose-Einstein condensates in optical lattice. It is found that there exist tunneling effects and fluctuations between lattices l and l ＋ 1, l and l - 1, respectively. In particular, when the optical lattice is infinitely long and the spin excitations are in the long-wavelength limit, tunneling effects disappear between lattices I and l＋ 1, and I and l - 1. In this case the fluctuations are a constant, and the magnetic soliton appears.

Dynamics and Manipulation for Gap Solitons in Bose-Einstein Condensates under Optical Lattice and Harmonic Potentials

By means of an extended variational approach,we study dynamics for gap solitons in a repulsive interactionBose-Einstein condensate under both a harmonic and an optical lattice confinement.The simplified analytic theorygives the critical strength ratio of harmonic to optical lattice necessary to support multiple stable lattice sites for thecondensate.Moreover,we use numerical experiments to guide and manipulate the gap solitons to an arbitrary positionvia a time-dependent potential.All predictions of the extended variational approach are reasonably close to results ofthe simulations.In particular,the variational model helps capture the composition relationship between the variationsof chirp and amplitude.

Dynamic Subcarrier Assignment for OFDM-PON Network Based on RSOA for ACCORDANCE

In this paper, we overview the principle of Orthogonal Frequency Division Multiplexing Passive Optical Network （OFDM-PON） systems, with a particular focus on upstream architectures capable of achieving 10Gbit/s colorless upstream transmission using Reflective Semiconductor Optical Amplifier （RSOA）. We propose an architecture of RSOA based OFDM-PON which can achieve 10Gbit/s upstream transmission over a single wavelength. A novel Dynamic Subcarrier Assignment （DSA） algorithm is also proposed to support my architecture, namely Service based Polling in Pipeline （SPP） dynamic subcarrier algorithm. A simulation was conducted to study the performance of SPP algorithm. Compared with the traditional dynamic bandwidth allocation algorithms, service based polling meets the quality of in pipeline algorithm service requirements excellently, and adapts orthogonal frequency division multiplexing passive optical network better with higher bandwidth efficiency and lower algorithm complexity.

Reducing current fluctuation of Cs3Bi2Br9 perovskite photodetectors for diffuse reflection imaging with wide dynamic range

Recently,the newly booming metal halide perovskites have attracted extensive attention worldwide due to their outstanding optoelectronic performance,and are expected to be ideal candidates for photodetectors(PDs).However,there is still lack of perovskite PDs-based imaging devices coming into commercialization stage,due to some practical reasons including toxicity brought by lead-based perovskites and the large light current fluctuations.In this paper,for the first time we fabricate a lead-free Cs3Bi2Br9 perovskite PD,and build a prototype of this perovskite PD-based imaging system with diffuse reflection imaging mode.Moreover,we propose a new parameter F related to light current fluctuation to evaluate imaging performance of a PD especially for weak diffuse light condition,and prove its usability by comparison of unoptimized lead-free Cs3Bi2Br9 perovskite PD and atomic layer deposition(ALD)optimized Cs3Bi2 Br9 PD.ALD-optimization can improve the quality of perovskite film and suppress the dark current and current fluctuation.Finally,we obtain satisfactory diffuse reflection images of 2D and 3D objects with wide dynamic range.Therefore,the ALD-optimized Cs3Bi2Br9PD has addressed two major concerns about perovskite PDs-based imaging devices,that may extend application of perovskite materials and improve imaging quality.

Single-photon microwave photonics

With the rapid development of microwave photonics technology, high-speed processing and ultra-weak signal detection capability have become the main bottlenecks in many applications. Thanks to the ultraweak signal detection capability and the extremely low timing jitter properties of single-photon detectors, the combination of single-photon detection and classical microwave photonics technology may provide a solution to break the above bottlenecks. In this paper, we first report a novel concept of singlephoton microwave photonics(SP-MWP), a SP-MWP signal processing system with phase shifting and frequency filtering functionalities is demonstrated based on a superconducting nanowire single photon detector(SNSPD) and a successive time-correlated single photon counting(TCSPC) module.Experimental results show that an ultrahigh optical sensitivity down to-100 d Bm has been achieved,and the signal processing bandwidth is only limited by the timing jitter of single-photon detectors. In the meantime, the proposed system demonstrates an ultrahigh anti-interference capability, only the signal which is phase locked by the trigger signal in TCSPC can be extracted from the detected signals combining with noise and strong interference. The proposed SP-MWP concept paves a way to a novel interdisciplinary field of microwave photonics and quantum mechanism, named by quantum microwave photonics.

A microwave photonic link with high spurious-free dynamic range based on a parallel structure

A microwave photonic link （MPL） with high spurious-free dynamic range （SFDR） is proposed and analyzed. The optical carrier is divided equally into two paths. The path I is modulated by radio frequency （RF） signals in a Mach-Zehnder modulator （MZM）, and the phase of path 2 is controlled before the combination with path 1. By properly adjusting the phase difference of the two paths with the optical phase shifter, the third-order intermodulation distortion （IMD3） can be significantly suppressed. A proof-of-concept simulation is carried out. The results show that a reduction of 40 dB in the IMD3 and an improvement of 21.1 dB in the SFDR are achieved as compared with the conventional MZM-based MPL. The proposed MPL shows the advantages of simple structure, low cost and high efficiency.