Nano slit arrays perforated on thin metallic film are the basic structure of metallic nano-optic lenses, which resemble the
shape of the conventional glass lens, and can be applied to beam manipulation, such as beam reflecting/deflecting or
focusing. It has been proven that optical transmission is feasible through metallic nano slit arrays, making new nano
technology applications possible. In conventional dielectric lenses, the edge effect-the very strong diffraction of the
transmitted beam that take place at the lens edges restricts the possibility of sizing down the conventional optics
components to a sub-wavelength range. This is due to the fact that the size of the lens is an important determinant of
focusing beam to the nano scale.
In this paper we present the metallic nano lenses and study their optical transmission properties. These lenses do not
suffer from the edge effect mentioned above. The phase of each nanoslit element can be managed by changing the
material of the metal film and/or the structural parameters of the lens. In our simulation work, we examine the
transmission performance of metallic nano slit arrays by the method of finite-difference time-domain (FDTD). We use
various metals such as copper, silver, aluminum and titanium as the material of the thin films. We also investigate
various structural parameters such as slit number, width and thickness, to show their influence on the optical
transmission performance. By adjusting the material and/or structural parameters of the Nano slit arrays, the desired
transmission performance can be realized.
Orthogonal Frequency Division Multiplex (OFDM) is a modulation technique to transmit the baseband Radio signals
over Fiber (RoF). Combining OFDM modulation technique and radio over fiber technology will improve future wireless
communication. This technique can be implemented using laser and photodetector as optical modulator and
demodulator. OFDM uses multiple sub-carriers to transmit low data rate streams in parallel, by using Quadrature
Amplitude Modulation (QAM) or Phase Shift Keying (PSK). In this paper we will compare power spectrum signal and
signal constellation of transmitted and received signals in RoF using Matlab and OptiSystem simulation software.
Proc. SPIE. 7797, Optics and Photonics for Information Processing IV
KEYWORDS: Signal to noise ratio, Transmitters, Receivers, Telecommunications, Antennas, Wireless communications, Data communications, Orthogonal frequency division multiplexing, Signal detection, Mobile communications
By increasing multimedia communications, mobile communications are expected to reliably support high data rate
transmissions. To provide higher peak rate at a better system efficiency, which is necessary to support broadband data
services over Wireless links, we need to employ long term evolution Advanced (LTE-A) Multiple-input multiple-output
MIMO uplink. The outline of this paper is to investigate and discuss the Long Term Evolution (LTE) for broadband
wireless technologies and to discuss its functionality. We explore how LTE uses the inter-technology mobility to support
a variety of access technology.
This paper investigates the channel capacity and bit error rate of MIMO-OFDM system. In addition, it introduces various
MIMO technologies employed in LTE and provide a brief overview on the MIMO technologies currently discussed in
the LTE-Advanced forum.
Proc. SPIE. 7797, Optics and Photonics for Information Processing IV
KEYWORDS: Code division multiplexing, Signal to noise ratio, Modulation, Networks, Telecommunications, Computer engineering, Data communications, Orthogonal frequency division multiplexing, Frequency division multiplexing, Standards development
Wideband code division multiple access (WCDMA) is currently being extended into high-speed downlink access
(HSDPA) and high-speed uplink packet access (HSUPA). The continuing research of next generation communication
proposed by 3GPP is named long term evolution (LTE). The main goal of LTE Release is to offer high peak downlink
and uplink rates by the use of Orthogonal Frequency-Division Multiple Access (OFDMA) that attributes a very flexible
multi-user bandwidth, high spectral efficiency and scalable bandwidth. The benefit of LTE is the fact that it offers higher
data rates in both uplink and downlink and enhances the services for the terminals.
A notable fact is that several WiMAX projects have been reoriented toward Long Term Evolution (LTE), mainly aimed
at increasing performance. In this paper the challenge of scheduling user transmissions on the downlink of LTE cellular
communication system is discussed. Various results show that the system performance improves with increasing
correlation among OFDMA subcarriers.
The radio-over-fiber (RoF) network has been a proven technology to be the best candidate for the wireless-access
technology, and the orthogonal frequency division multiplexing (OFDM) technique has been established as the core
technology in the physical layer of next generation wireless communication system, as a result OFDM-RoF has drawn
attentions worldwide and raised many new research topics recently.
At the present time, the trend of information industry is towards mobile, wireless, digital and broadband. The next
generation network (NGN) has motivated researchers to study higher-speed wider-band multimedia communication to
transmit (voice, data, and all sorts of media such as video) at a higher speed. The NGN would offer services that would
necessitate broadband networks with bandwidth higher than 2Mbit/s per radio channel. Many new services emerged,
such as Internet Protocol TV (IPTV), High Definition TV (HDTV), mobile multimedia and video stream media. Both
speed and capacity have been the key objectives in transmission. In the meantime, the demand for transmission
bandwidth increased at a very quick pace. The coming of 4G and 5G era will provide faster data transmission and higher
bit rate and bandwidth.
Taking advantages of both optical communication and wireless communication, OFDM Radio over Fiber (OFDM-RoF)
system is characterized by its high speed, large capacity and high spectral efficiency. However, up to the present there
are some problems to be solved, such as dispersion and nonlinearity effects. In this paper we will study the dispersion
and nonlinearity effects and their elimination in OFDM-radio-over-fiber system.
In this paper we present the effect of gold, silver and oxide thicknesses on the sensitivity of Surface Plasmon
Resonance (SPR). SPR sensor with enhanced sensitivities can be realized based on gold/silver films. Surface
Plasmons (SP) are electromagnetic waves that transmit along the interference between a metal and a dielectric
film, and the electromagnetic wave of the surface plasmons is coupled to oscillations of free electrons in the metal.
SPR has attracted interest in many applications such as solar cells, chemical and biological sensing. The potential
sensor application by using gold/silver nanocrystal enhanced SPR phenomenon. Sensitivity is a significant
parameter to assess the sensor's performance. Essentially, sensitivity is determined by the force of light and matter
Photovoltaic absorbers ought to be optically thick to allow almost total light absorption and photocarrier current
collection. They are typically semiconductors with a thickness more than the optical absorption length. When the
absorber layer thickness is reduced significantly, then the quality of the absorber material could considerably
increase by allowing resourceful photocarrier collection across tiny distances in structures such as quantum wells
or quantum dots. For absorber layers with fine surface passivation, the capability to reduce the solar cell base
thickness by means of plasmonic design improves carrier collection. The objective of this paper is to show how
plasmonics could be exploited to our benefit in high efficiency photovoltaics.
Tunable semiconductor laser has various applications including Wavelength Division Multiplexing (WDM), Frequency Division Multiplexing (FDM), optical switching in Local Area Networks (LAN) and Chemical Sensing, or Spectroscopy. There are different approaches for tunable semiconductor lasers. Large wavelength tuning range is required for communication applications, such as WDM. Whereas a frequency modulation (FM) requires small but fast frequency shifts. Two-Segment laser is one of the methods to realize continuous
optical tuning. The device consists of two coupled cavities having a series of well-defined modes. The modes are equally spaced within a cavity but the mode spacing between the two cavities is slightly different. Characterization results of such lasers are very important. In this paper we will present the characterization
results of two segment InGaAs/InP distributed feed back (DFB) tunable lasers.
Monocrystals of gallium selenide (GaSe) has recently attracted significant attention in the field of new optoelectronic devices, due to the original combination of its specific features such as nonlinear optical properties, layered structure and high-photo sensitivity. GaSe crystals show both high reflectivity and unique surface perfection, which leads to a promising candidate for next generation optical devices. We will present our experimental results of reflection spectra of such crystals for various temperatures (273°K-383°K) and applied electric field (1 V/cm - 20 V/cm). The reflection
spectra were analyzed to identify the mechanism of the reflective coefficient change in GaSe as a function of wavelength, temperature and electric field. This study will identify the optimal electrical field regimes and spectral segments, where we experimentally revealed
reflective properties of GaSe are suitable for creating the field regulated optical applications of decoder and depolarizer. The temperature dependence of GaSe reflectance spectrum, its temperature and applied field dependences exemplified that the processes of photon-electron inter-exchanging on the surfaces are dominated over the bulk processes in forming the reflectance properties of layered crystals. The perfectness of natural surface and their high reflective properties weren't changed in the interval of experimental temperatures. The monolayer surface of GaSe can be utilized as an easy
prepared natural plane surface for new optical devices on their surface basis in their original combinations. Such devises are applicable for optical information processing systems because of the stability function and weak dependence of the function of bulk properties.