Wavelength multiplexing and tuning in nano-Ag/dielectric multilayers

Multicolored optical active planes have been fabricated with magnetron sputter method coupled with selective masking technique. The plane is multilayer structured with Ag nanoparticles and TiO2 thin layer as the building blocks. It was found that the formed multilayer can be readily wavelength multiplexed by simply overlapping several nano-Ag/TiO2 layered structures, each of which may have different surface plasmon resonance wavelength. Unlike high order multiple resonances of large particles each of the multiplexing wavelengths in such a system is separately tunable. Importantly, it reveals that modification of the TiO2 layer thickness generates a fine tuning of the resonance wavelength.

Wavelength multiplexing and tuning in nano-Ag/dielectric multilayers

Multicolored optical active planes have been fabricated with magnetron sputter method coupled with selective masking technique. The plane is multilayer structured with Ag nanoparticles and TiO2 thin layer as the building blocks. It was found that the formed multilayer can be readily wavelength multiplexed by simply overlapping several nano-Ag/TiO2 layered structures, each of which may have different surface plasmon resonance wavelength. Unlike high order multiple resonances of large particles each of the multiplexing wavelengths in such a system is separately tunable. Importantly, it reveals that modification of the TiO2 layer thickness generates a fine tuning of the resonance wavelength.

Quantum metropolitan optical network based on wavelength division multiplexing

Quantum Key Distribution (QKD) is maturing quickly. However, the current approaches to its application in optical networks make it an expensive technology. QKD networks deployed to date are designed as a collection of point-to-point, dedicated QKD links where non-neighboring nodes communicate using the trusted repeater paradigm. We propose a novel optical network model in which QKD systems share the communication infrastructure by wavelength multiplexing their quantum and classical signals. The routing is done using optical components within a metropolitan area which allows for a dynamically any-to-any communication scheme. Moreover, it resembles a commercial telecom network, takes advantage of existing infrastructure and utilizes commercial components, allowing for an easy, cost-effective and reliable deployment.

A wideband sensitive holographic photopolymer

A novel wideband sensitive dry holographic photopolymer sensitized by rose bengal (RB) and methylene blue (MB) is fabricated, the holographic storage characteristics of which are investigated under different exposure wavelengths. The result shows that the sensitive spectral band exceeds 200 nm in visible light range, the maximum diffraction efficiency under different exposure wavelengths is more than 40% and decreases with the decrease of exposure wavelength, the exposure sensitivity is not change with the exposure wavelength. This photopolymer is appropriate for wavelength multiplexing or multi-wavelength recording in digital holographic storage.

光纤耦合波长复用的全息光盘存储记录

详细描述了用光纤耦合、波长复用的全息光盘仔储光路．指出在全息光盘驱动器即将市场化的今天．由于其光路简单、光学元件较少、性价比高．很有可能成为新的全息光盘驱动器的核心技术之一。由于短波长单模光纤及其双波长光纤分束器件的要求比较高．而用多模光纤进行准单模输出调整．以及用分光棱镜进行光束的分光．同时用对双波长敏感的光致聚合物材料进行存储．其光谱灵敏度均匀．光谱范围互不重叠。实验结果表明．光路结构合理．存储效果良好。

A new metal ion doped panchromatic photopolymer for holographic applications

This thesis has discussed the development of a new metal ion doped panchromatic photopolymer for various holographic applications. High-quality panchromatic holographic recording material with high diffraction efficiency, high photosensitivity and high spatial resolution is one of the key factors for the successful recording of true colour holograms. The capability of the developed material for multicolour holography can be investigated.In the present work, multiplexing studies were carried out using He-Ne laser (632.8 nm). Multiplexing can be done using low wavelength lasers like Ar+ ion (488 nm) and frequency doubled Nd: YAG (532 nm) lasers, so as to increase the storage capacity. The photopolymer film studied had a thickness of only 130 Cm. Films with high thickness (~500 Cm) is highly essential for competitive holographic memories . Hence films with high thickness can be fabricated and efforts can be made to record more holograms or gratings in the material.In the present study, attempts were made to record data page in silver doped MBPVA/AA photopolymer film. Image of a checkerboard pattern was recorded in the film, which could be reconstructed with good image fidelity. Efforts can be made to determine the bit error rate (BER) which provides a quantitative measure of the image quality of the reconstructed image . Multiple holographic data pages can also be recorded in the material making use of different multiplexing techniques.Holographic optical elements (HOEs) are widely used in optical sensors, optical information processing, fibre optics, optical scanners and solar concentrators . The suitability of the developed film for recording holographic optical elements like lenses, beam splitters and filters can be studied.The suitability of a reflection hologram recorded in acrylamide based photopolymer for visual indication of environmental humidity is reported . Studies can be done to optimize the film composition for recording of reflection holograms.An improvement in the spatial resolution of PVA/acrylamide based photopolymer by using a low molecular-weight poly (vinyl alcohol) binder was recently reported . Effect of the molecular weight of the binder matrix on the holographic properties of the developed photopolymer system can be investigated.Incorporation of nanoparticles into photopolymer system is reported to enhance the resolution and improve the dimensional stability of the system . Hence efforts can be made to incorporate silver nanoparticles into the photopolymer and its influence on the holographic properties can be studied.This thesis was a small venture towards the realization of a big goal, a competent holographic recording material with excellent properties for practical holographic applications. As a result of the present research, we could successfully develop an efficient panchromatic photopolymer system and could demonstrate its suitability for recording transmission holograms and holographic data page. The developed photopolymer system is expected to have significant applications in the fields of true-color display holography, wavelength multiplexing holographic storage, and holographic optical elements. Highly concentrated and determined effort has yet to be put forth for this expectation to become a reality.

Exploitation of fibre characteristics in temperature sensing and radio-over-fibre applications

The development of sensing devices is one of the instrumentation fields that has grown rapidly in the last decade. Corresponding to the swift advance in the development of microelectronic sensors, optical fibre sensors are widely investigated because of their advantageous properties over the electronics sensors such as their wavelength multiplexing capability and high sensitivity to temperature, pressure, strain, vibration and acoustic emission. Moreover, optical fibre sensors are more attractive than the electronics sensors as they can perform distributed sensing, in terms of covering a reasonably large area using a single piece of fibre. Apart from being a responsive element in the sensing field, optical fibre possesses good assets in generating, distributing, processing and transmitting signals in the future broadband information network. These assets include wide bandwidth, high capacity and low loss that grant mobility and flexibility for wireless access systems. Among these core technologies, the fibre optic signal processing and transmission of optical and radio frequency signals have been the subjects of study in this thesis. Based on the intrinsic properties of single-mode optical fibre, this thesis aims to exploit the fibre characteristics such as thermal sensitivity, birefringence, dispersion and nonlinearity, in the applications of temperature sensing and radio-over-fibre systems. By exploiting the fibre thermal sensitivity, a fully distributed temperature sensing system consisting of an apodised chirped fibre Bragg grating has been implemented. The proposed system has proven to be efficient in characterising grating and providing the information of temperature variation, location and width of the heat source applied in the area under test.To exploit the fibre birefringence, a fibre delay line filter using a single high-birefringence optical fibre structure has been presented. The proposed filter can be reconfigured and programmed by adjusting the input azimuth of launched light, as well as the strength and direction of the applied coupling, to meet the requirements of signal processing for different purposes in microwave photonic and optical filtering applications. To exploit the fibre dispersion and nonlinearity, experimental investigations have been carried out to study their joint effect in high power double-sideband and single-sideband modulated links with the presence of fibre loss. The experimental results have been theoretically verified based on the in-house implementation of the split-step Fourier method applied to the generalised nonlinear Schrödinger equation. Further simulation study on the inter-modulation distortion in two-tone signal transmission has also been presented so as to show the effect of nonlinearity of one channel on the other. In addition to the experimental work, numerical simulations have also been carried out in all the proposed systems, to ensure that all the aspects concerned are comprehensively investigated.

Análise de conversores de frequência óptica baseados em amplificadores ópticos semicondutores

Dissertação de mest. em Engenharia de Sistemas e Computação, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2002

High-efficiency reflective diffraction gratings in fused silica as (de)multiplexers at 1.55 mu m for dense wavelength division multiplexing application

We describe high-efficiency, high-dispersion reflection gratings fabricated in bulk fused Silica illuminated by incident lights in the C + L bands as (de)multiplexers for dense wavelength division multiplexing (DWDM) application. Based on the phenomenon of total internal reflection, gratings with optimized profile parameters exhibit diffraction efficiencies of more than 90% under TM- and TE-polarized incident lights for 101-nm spectral bandwidths (1520-1620 nm) and can reach an efficiency of greater than 97% for both polarizations at a wavelength of 1550 nm. Without loss of metal absorption, without coating of dielectric film layers, and independent of tooth shape, this new kind of grating should be of great interest for DWDM application. (C) 2005 Optical Society of America.

Quantum key distribution for 10 Gb/s dense wavelength division multiplexing networks

We demonstrate quantum key distribution (QKD) with bidirectional 10 Gb/s classical data channels in a single fiber using dense wavelength division multiplexing. Record secure key rates of 2.38 Mbps and fiber distances up to 70km are achieved. Data channels are simultaneously monitored for error-free operation. The robustness of QKD is further demonstrated with a secure key rate of 445 kbps over 25km, obtained in the presence of data lasers launching conventional 0 dBm power. We discuss the fundamental limit for the QKD performance in the multiplexing environment. © 2014 AIP Publishing LLC.