Holographic mode-selective launch for bandwidth enhancement in multimode fiber

With rapidly growing bandwidth demands in Local Area Networks, it is imperative to support next generation speeds beyond 40Gbit/s.Various holographic optimization techniques using spatial light modulators have recently been explored for adaptive channel impulse response improvement of MMF links. Most of these experiments are algorithmic-oriented. In this paper, a set of lenses and a spatial light modulator, acting as a binary amplitude filter, played the pivotal role in generating the input modal electric field into a graded-index MMF, rather than algorithms. By using a priori theoretical information to generate the incident modal electric field at the MMF, the bandwidth was increased by up to 3.4 times

Multidiameter optical ring and Hermite–Gaussian vortices for wavelength division multiplexing–mode division multiplexing

Optical vortices are high-capacity data carriers for mode division multiplexing (MDM) in multimode fiber (MMF). This paper reports on the MDM of a combination of helical-phased optical vortices comprising donut modes and Hermite–Gaussian (HG) modes for different radial offsets from the MMF axis. A data rate of 44 Gbps is achieved for wavelength division multiplexing–MDM of two pairs of helical-phased donut mode and HG mode at wavelengths 1550.12 and 1551.72 nm for a MMF length of 1500 m

Binary spatial amplitude modulation of continuous transverse modal electric field using a single lens for mode selectivity in multimode fiber

The demand for portable real-time optical applications such as medical optical sensors and optical transceivers instigate the need for compact optical designs.The aim of this paper is to demonstrate a new, compact design for binary spatial amplitude modulation in a multimode fiber-based optical transceiver, adapted from microscopy.The continuous-amplitude transverse modal electric field of an infinite parabolic multimode fiber is retrieved from a binary amplitude-modulated field using a single lens.The retrieved field is in good agreement with the original modal electric field

Binary encoded computer generated holograms for temporal phase shifting

The trend towards real-time optical applications predicates the need for real-time interferometry.For real-time interferometric applications, rapid processing of computer generated holograms is crucial as the intractability of rapid phase changes may compromise the input to the system. This paper introduces the design of a set of binary encoded computer generated holograms (CGHs) for real-time five-frame temporal phase shifting interferometry using a binary amplitude spatial light modulator.It is suitable for portable devices with constraints in computational power. The new set of binary encoded CGHs is used for measuring the phase of the generated electric field for a real-time selective launch in multimode fiber. The processing time for the new set of CGHs was reduced by up to 65% relative to the original encoding scheme.The results obtained from the new interferometric technique are in good agreement with the results obtained by phase shifting by means of a piezo driven flat mirror

An optical synchronous up counter based on electro-optic effect of lithium niobate based Mach–Zehnder interferometers

Sequential circuits have the ability to store, retain and then retrieve information when needed at a later time. They act as storage elements and have memory. However, due to ever increasing demand of data rate, already existing electronic signal processing devices have become obsolete due to their large latency. To overcome the existing bottleneck, a 4-bit synchronous up counter using electro-optic effect of Mach–Zehnder interferometer has been proposed. The study is carried out by simulating the proposed device with beam propagation method

Multimedia Traffic Routing in Multilayer WDM Networks

The advent of real-time multimedia services over the Internet has stimulated new technologies for expanding the information carrying capacity of optical network backbones. Multilayer wavelength division multiplexing (WDM) packet switching is an emerging technology for increasing the bandwidth of optical networks. Two algorithms for the routing of the multimedia traffic flows were applied: (i) Capacitated Shortest Path First (CSPF) routing, which minimizes the distance of each flow linking the given source and destination nodes and satisfying capacity constraints; and (ii) Flow Deviation Algorithm (FDA) routing, which minimizes the network-wide average packet delay.Comment: 10 pages, 8 figure

Implementation of 2-bit multiplier based on electro-optic effect in Mach–Zehnder interferometers

This paper demonstrates the structure and working principle of an optical 2-bit multiplier using lithium niobate (LiNbO[subscript 3]) based Mach–Zehnder interferometer (MZI). The powerful ability of MZI structures to switch the optical signal from one output port to the other output port has been used in the implementation of the proposed 2-bit multiplier. The paper constitutes the mathematical description of the 2-bit multiplier and thereafter compilation using MATLAB. The study is carried out by simulating the proposed device with Beam propagation method (BPM).DIT University (Faculty Research Scheme Ref. No.: DITU/R&D/2014/7/ECE

Mode Division Multiplexing of LG and HG modes in Ro-FSO

Radio-over-free-space-optics (Ro-FSO) is a strongcontender for providing a ubiquitous platform for seamlessintegration of high capacity radio and optical networks withoutexpensive optical fiber cabling. This work presents mode divisionmultiplexing of LG and HG modes in a 40 GHz Ro-FSOtransmission system to realize 4 x 20Gbps over a free space opticallink under clear weather conditions. The signal-to-noise-ratio,received power and constellations will be analyzed

2x20 Gbps - 40 GHz OFDM Ro-FSO transmission with mode division multiplexing

Radio-over-Free-Space-Optics (Ro-FSO) is a promising technology for future wireless networks.In this work, we have designed a hybrid orthogonal frequency division multiplexing (OFDM) Ro-FSO system for transmission of two independent channels by mode division multiplexing.Two independent 40 GHz radio signals are optically modulated at 20Gbps by mode division multiplexing of two laser modes LG00 and LG10 and transmitted over a free-space link of 20 km to 100 km. The performance of proposed Ro-FSO system is also evaluated under the effect of strong atmospheric turbulences

Design of Excess 3 to BCD code converter using electro-optic effect of Mach-Zehnder Interferometers for efficient data transmission

Excess 3 code is one of the most important codes used for efficient data storage and transmission. It is a non-weighted code and also known as self complimenting code. In this paper, a four bit optical Excess 3 to BCD code converter is proposed using electro-optic effect inside lithium-niobate based Mach-Zehnder interferometers (MZIs). The MZI structures have powerful capability to switching an optical input signal to a desired output port. The paper constitutes a mathematical description of the proposed device and thereafter simulation using MATLAB. The study is verified using beam propagation method (BPM).Dehradun Institute of Technology (Dehradun, India). Faculty Research Scheme (Ref. No.: DITU/R&D/2014/7/ECE