The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Paul R Prucnal - One of the best experts on this subject based on the ideXlab platform.

  • compact optical steganography based on Amplified Spontaneous Emission noise
    IEEE Photonics Conference, 2015
    Co-Authors: Matthew P Chang, Bhavin J Shastri, Alexander N Tait, Paul R Prucnal
    Abstract:

    We experimentally demonstrate a compact optical steganography method using chirped fiber Bragg gratings. The stealth signals are carried by wide band Amplified Spontaneous Emission noise, which has strong dispersion effect for pulse stretching.

  • wdm optical steganography based on Amplified Spontaneous Emission noise
    Optics Letters, 2014
    Co-Authors: Alexander N Tait, Matthew P Chang, Paul R Prucnal
    Abstract:

    We propose and experimentally demonstrate a wavelength-division multiplexed (WDM) optical stealth transmission system carried by Amplified Spontaneous Emission (ASE) noise. The stealth signal is hidden in both time and frequency domains by using ASE noise as the signal carrier. Each WDM channel uses part of the ASE spectrum, which provides more flexibility to apply stealth transmission in a public network and adds another layer of security to the stealth channel. Multi-channel transmission also increases the overall channel capacity, which is the major limitation of the single stealth channel transmission based on ASE noise. The relations between spectral bandwidth and coherence length of ASE carrier have been theoretically analyzed and experimentally investigated.

  • temporal phase mask encrypted optical steganography carried by Amplified Spontaneous Emission noise
    Optics Express, 2014
    Co-Authors: Ben Wu, Bhavin J Shastri, Matthew P Chang, Nicholas A Frost, Zhenxing Wang, Paul R Prucnal
    Abstract:

    A temporal phase mask encryption method is proposed and experimentally demonstrated to improve the security of the stealth channel in an optical steganography system. The stealth channel is protected in two levels. In the first level, the data is carried by Amplified Spontaneous Emission (ASE) noise, which cannot be detected in either the time domain or spectral domain. In the second level, even if the eavesdropper suspects the existence of the stealth channel, each data bit is covered by a fast changing phase mask. The phase mask code is always combined with the wide band noise from ASE. Without knowing the right phase mask code to recover the stealth data, the eavesdropper can only receive the noise like signal with randomized phase.

  • optical steganography based on Amplified Spontaneous Emission noise
    Optics Express, 2013
    Co-Authors: Zhenxing Wang, Bhavin J Shastri, Yue Tian, Mable P Fok, Daniel R Kanoff, Paul R Prucnal
    Abstract:

    We propose and experimentally demonstrate an optical steganography method in which a data signal is transmitted using Amplified Spontaneous Emission (ASE) noise as a carrier. The ASE serving as a carrier for the private signal has an identical frequency spectrum to the existing noise generated by the Erbium doped fiber amplifiers (EDFAs) in the transmission system. The system also carries a conventional data channel that is not private. The so-called “stealth” or private channel is well-hidden within the noise of the system. Phase modulation is used for both the stealth channel and the public channel. Using homodyne detection, the short coherence length of the ASE ensures that the stealth signal can only be recovered if the receiver closely matches the delay-length difference, which is deliberately changed in a dynamic fashion that is only known to the transmitter and its intended receiver.

  • Phase-mask covered optical steganography based on Amplified Spontaneous Emission noise
    2013 IEEE Photonics Conference, 2013
    Co-Authors: Ben Wu, Bhavin J Shastri, Yue Tian, Zhenxing Wang, Paul R Prucnal
    Abstract:

    Phase mask encryption is proposed to improve the transmission privacy of an optical steganography system. The stealth signal carried by Amplified Spontaneous Emission noise is encrypted by a fast changing code.

Georgian Nedelcu - One of the best experts on this subject based on the ideXlab platform.

  • temperature dependence of the Amplified Spontaneous Emission from cspbbr3 nanocrystal thin films
    Journal of Physical Chemistry C, 2018
    Co-Authors: Antonio Balena, Georgian Nedelcu, Andrea Perulli, Manuel Fernandez, Maria Luisa De Giorgi, Maksym V Kovalenko, M Anni
    Abstract:

    Cesius lead halide perovskite colloidal nanocrystals are among the most promising perovskite systems for light-emitting devices applications due to their high fluorescence quantum yield and high optical gain at room temperature. In this letter, we report on the first investigation of temperature dependence of Amplified Spontaneous Emission (ASE) properties of thin films of CsPbBr3 nanocrystals. We demonstrate that ASE is strongly temperature-dependent, with a complex variation in temperature of the ASE intensity, threshold, and peak wavelength. The joint investigation of the photoluminescence (PL) spectra below and above the ASE threshold allows us to conclude that the temperature increase results in the formation of disordered subdomains emitting in the low-energy tail of the PL spectra, leading to the existence of three Emission regimes with transitions at about 90 and 170 K, with individually different temperature dependences.

  • low threshold Amplified Spontaneous Emission and lasing from colloidal nanocrystals of caesium lead halide perovskites
    Nature Communications, 2015
    Co-Authors: Sergii Yakunin, Loredana Protesescu, Franziska Krieg, Maryna I Bodnarchuk, Georgian Nedelcu
    Abstract:

    Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials. Despite the recent surge of reports on microcrystalline, thin-film and bulk single-crystalline metal halides, very little is known about the photophysics of metal halides in the form of uniform, size-tunable nanocrystals. Here we report low-threshold Amplified Spontaneous Emission and lasing from ∼10 nm monodisperse colloidal nanocrystals of caesium lead halide perovskites CsPbX3 (X=Cl, Br or I, or mixed Cl/Br and Br/I systems). We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440–700 nm) with low pump thresholds down to 5±1 μJ cm−2 and high values of modal net gain of at least 450±30 cm−1. Two kinds of lasing modes are successfully observed: whispering-gallery-mode lasing using silica microspheres as high-finesse resonators, conformally coated with CsPbX3 nanocrystals and random lasing in films of CsPbX3 nanocrystals. Lead halide perovskite colloidal nanocrystals have promising optoelectronic properties, such as high photoluminescence quantum yields and narrow Emission linewidths. Here, the authors report low-threshold Amplified Spontaneous Emission and two kinds of lasing in nanostructured caesium lead halide perovskites.

Clement Yuen - One of the best experts on this subject based on the ideXlab platform.

  • ultraviolet Amplified Spontaneous Emission from self organized network of zinc oxide nanofibers
    Applied Physics Letters, 2005
    Co-Authors: Xiao Wei Sun, Clement Yuen, B J Chen, Zhili Dong
    Abstract:

    Self-organized zinc oxide (ZnO) nanofiber network with six-fold symmetry was fabricated on ZnO-buffered (0001) sapphire substrate with patterned gold catalyst by vapor-phase transport method. From the ZnO buffer layer, hexagonal ZnO nanorods with identical in-plane structure grew epitaxially along [0001] orientation to form vertical stems. The nanofiber branches grew horizontally from six side-surfaces of the vertical stem along [011¯0] and other equivalent directions. The aligned network structure constructed a waveguide array with optical gain. Ultraviolet Amplified Spontaneous Emission was observed along the side-branching nanofibers when the aligned ZnO network was excited by a frequency-tripled Nd:YAG laser.

  • ultraviolet Amplified Spontaneous Emission from zinc oxide ridge waveguides on silicon substrate
    Applied Physics Letters, 2003
    Co-Authors: Clement Yuen, Shu Ping Lau, Y G Wang, Heung Wing Joseph Lee, B K Tay
    Abstract:

    Zinc oxide (ZnO) thin-film waveguides with ridge structures have been fabricated on n-type (100) silicon substrates. The deposition of high-crystal-quality ZnO thin films on the lattice-mismatched silicon substrate was achieved by using the filtered cathodic vacuum arc technique. A ridge structure is defined on the ZnO thin film by plasma etching. Room temperature Amplified Spontaneous Emission with peak wavelength at 385 nm is observed under 355 nm optical excitation. The pump threshold is found to be around 0.45 MW/cm2. The maximum net optical gain of the ZnO waveguide is larger than 120 cm−1 at a pump intensity of 1.9 MW/cm2.

Xiao Zhu - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of Amplified Spontaneous Emission in thin disk lasers using the spectral linewidth
    Optics Express, 2019
    Co-Authors: Yongqia Che, Guangzhi Zhu, Hantia Che, Keming Che, Haili Wang, Kozlov Aleksei, Mu Wang, Xiao Zhu
    Abstract:

    Amplified Spontaneous Emission (ASE) is important to power scaling of the large-scale, high-gain thin disk laser. In this paper, spectral properties of ASE in Yb:YAG thin disk lasers are deeply studied in both theory and experiment. The experimental results show that the ASE strength is much stronger when emitted from the edge surface than the pumping area. And the spectrum of ASE emitted from the coarsened edge surface is angle independent. Meanwhile, the reabsorption effect in the Yb:YAG crystal on spectral linewidth is analyzed and corrected. Finally, ASE spectral linewidths have been measured. We demonstrate that the spectral linewidths can evaluate ASE strength effectively.

B K Tay - One of the best experts on this subject based on the ideXlab platform.

  • ultraviolet Amplified Spontaneous Emission from zinc oxide ridge waveguides on silicon substrate
    Applied Physics Letters, 2003
    Co-Authors: Clement Yuen, Shu Ping Lau, Y G Wang, Heung Wing Joseph Lee, B K Tay
    Abstract:

    Zinc oxide (ZnO) thin-film waveguides with ridge structures have been fabricated on n-type (100) silicon substrates. The deposition of high-crystal-quality ZnO thin films on the lattice-mismatched silicon substrate was achieved by using the filtered cathodic vacuum arc technique. A ridge structure is defined on the ZnO thin film by plasma etching. Room temperature Amplified Spontaneous Emission with peak wavelength at 385 nm is observed under 355 nm optical excitation. The pump threshold is found to be around 0.45 MW/cm2. The maximum net optical gain of the ZnO waveguide is larger than 120 cm−1 at a pump intensity of 1.9 MW/cm2.