Efficient Characterizations of Multiphoton States with Ultra-thin Integrated Photonics

Metasurface enables the generation and manipulation of multiphoton entanglement with flat optics, providing a more efficient platform for large-scale photonic quantum information processing. Here, we show that a single metasurface optical chip would allow more efficient characterizations of multiphoton entangled states, such as shadow tomography, which generally requires fast and complicated control of optical setups to perform projective measurements in different bases, a demanding task using conventional optics. The compact and stable device here allows implementations of general positive observable value measures with a reduced sample complexity and significantly alleviates the experimental complexity to implement shadow tomography. Integrating self-learning and calibration algorithms, we observe notable advantages in the reconstruction of multiphoton entanglement, including using fewer measurements, having higher accuracy, and being robust against optical loss. Our work unveils the feasibility of metasurface as a favorable integrated optical device for efficient characterization of multiphoton entanglement, and sheds light on scalable photonic quantum technologies with ultra-thin integrated optics.Comment: 15 pages, 9 figure

Coexistence and evolution of bright pulses and dark solitons in a fiber laser

Bright pulses and dark solitons coexisting and evolving in a fiber laser with strong normal dispersion have been observed. Experimental results show that there exists a transitional pulse regime with the pulse duty cycle of similar to 0.5 that connects the bright pulse and dark soliton regimes. On adjusting polarization states and pump power, the duty cycle of pulses varies so that the laser emits bright, transitional, and dark pulses alternately. It is found that dark solitons are composed of two antiphase square pulses with very large durations and duty cycles. The experimental observations reveal that the bright and dark solitons are not completely isolated from each other. This work could provide a new perspective to the understanding of bright and dark soliton formations as well as their transformations. (C) 2013 Elsevier B.V. All rights reserved

Optimized synthesis of fiber Bragg gratings with triangular spectrum for wavelength-interrogation application

A novel method for synthesizing arbitrary-shape triangular-spectrum fiber Bragg gratings (TS-FBGs) is proposed. It involves the use of a discrete layer peeling method for exploiting initial guess and a simulated annealing method for optimizing the desired grating parameter. By comparing it to the reported TS-FBGs synthesis methods, the proposed method has advantages of reducing the maximum index modulation and smoothing index modulation profile simultaneously. We employ the proposed method to synthesize FBGs with symmetric, asymmetric, and right-angled triangular spectrum, all of which have the low and smooth index modulation profiles. The synthesized gratings can act simple and cost-effective wavelength-interrogation devices in optical sensor systems

High-channel-count plasmonic filter with the metal-insulator-metal Fibonacci-sequence gratings

Fibonacci-sequence gratings based on metal–insulator–metal waveguides are proposed. The spectrum properties of this structure are numerically investigated by using the transfer matrix method. Numerical results demonstrate that the proposed structure can generate high-channel-count plasmonic stop bands and can find significant applications in highly integrated dense wavelength division multiplexing networks

Multiple responses of TPP-assisted near-perfect absorption in metal/Fibonacci quasiperiodic photonic crystal

Absorption properties in one-dimensional quasiperiodic photonic crystal composed of a thin metallic layer and dielectric Fibonacci multilayers are investigated. It is found that a large number of photonic stopbands can occur at the dielectric Fibonacci multilayers. Tamm plasmon polaritons (TPPs) with the frequencies locating at each photonic stopband are excited at the interface between the metallic layer and the dielectric layer, leading to almost perfect absorption for the energy of incident wave. By adjusting the length of dielectric layer with higher refractive-index or the Fibonacci order, the number of absorption peaks can be tuned effectively and enlarged significantly. (C) 2011 Optical Society of Americ

Unidirectional manipulation of surface plasmon polariton by dual-nanocavity in a T-shaped waveguide

A structure of two dimensional T-shaped metal-insulator-metal waveguide with dual-nanocavity is proposed The two nanocavities located at each side of the slit on the lower metallic surface act as band rejection filters and are capable of stopping the surface plasmon polaritons (SPPs) at the resonant wavelengths The Fabry-Perot interferometry theory and the Finite-Difference-Time-Domain method are utilized to investigate the proposed waveguide The numerical results demonstrate the realization of miniaturized photonic devices for effectively switching the SPPs propagation between the left and right waveguides in one direction (C) 2010 Elsevier B V All rights reserve

Perfect absorber supported by optical Tamm states in plasmonic waveguide

Based on a two-dimensional plasmonic metal-dielectric-metal (MDM) waveguide with a thin metallic layer and a dielectric photonic crystal in the core, a novel absorber at visual and near-infrared frequencies is presented. The absorber spectra and filed distributions are investigated by the transfer-matrix-method and the finite-difference time-domain method. Numerical results show that attributing to excitation of the optical Tamm states in the MDM waveguide core, the optical wave is trapped in the proposed structure without reflection and transmission, leading to perfect absorption as high as 0.991. The proposed absorber can find useful application in all-optical integrated photonic circuits. (C) 2011 Optical Society of Americ