scholarly journals All-optical demultiplexing of closely spaced multimedia radio signals using sub-picometer fiber Bragg grating

Author(s):  
Hatice Kosek

Subcarrier multiplexed (SCM) transmission of multimedia radio signals such as CATV (5-860 MHz), cellular wireless (900 MHz) and wireless LAN (2.4 GHz) over fiber is frequently used to deliver broadband services cost effectively. These multi-channel radio-over-fiber (ROF) links have interesting applications and can connect enhanced wireless hotspots that will support high speed wireless LAN services or low speed cellular services to different customers from the same antenna. The SCM signals need to be demultiplexed, preferably in the optical domain for many reasons. Prefiltering of SCM signals with fiber-based optical filters warrants the use of inexpensive photodetectors and increases network flexibility. However, realizing optical demultiplexing as sub-GHz level is challenging and thus necessitates optical filters with high selectivity and low insertion loss and distortion. We developed a novel sub-picometer all-optical bandpass filter by creating a resonance cavity using two closely matched fiber Bragg gratings (FBGs). This filter has a bandwidth of 120 MHz at -3 dB, 360 MHz at -10 dB and 1.5 GHz at -20 dB. Experimental results showed that the filter is capable of separating two radio frequency (RF) signals spaced as close as 50 MHz without significant distortion. When this demultiplexer was employed to optically separate 2.4 GHz and 900 MHz radio signals, it was found to be linear from -38 dBm to +6 dBm with ~ 25.5 dB isolation. There was no significant increment in the BER of the underlying multimedia data. Results verified that the fabricated narrow bandpass filter can be a potential candidate in demultiplexing of RF signals in networks based on subcarrier multiplexed schemes.

2021 ◽  
Author(s):  
Hatice Kosek

Subcarrier multiplexed (SCM) transmission of multimedia radio signals such as CATV (5-860 MHz), cellular wireless (900 MHz) and wireless LAN (2.4 GHz) over fiber is frequently used to deliver broadband services cost effectively. These multi-channel radio-over-fiber (ROF) links have interesting applications and can connect enhanced wireless hotspots that will support high speed wireless LAN services or low speed cellular services to different customers from the same antenna. The SCM signals need to be demultiplexed, preferably in the optical domain for many reasons. Prefiltering of SCM signals with fiber-based optical filters warrants the use of inexpensive photodetectors and increases network flexibility. However, realizing optical demultiplexing as sub-GHz level is challenging and thus necessitates optical filters with high selectivity and low insertion loss and distortion. We developed a novel sub-picometer all-optical bandpass filter by creating a resonance cavity using two closely matched fiber Bragg gratings (FBGs). This filter has a bandwidth of 120 MHz at -3 dB, 360 MHz at -10 dB and 1.5 GHz at -20 dB. Experimental results showed that the filter is capable of separating two radio frequency (RF) signals spaced as close as 50 MHz without significant distortion. When this demultiplexer was employed to optically separate 2.4 GHz and 900 MHz radio signals, it was found to be linear from -38 dBm to +6 dBm with ~ 25.5 dB isolation. There was no significant increment in the BER of the underlying multimedia data. Results verified that the fabricated narrow bandpass filter can be a potential candidate in demultiplexing of RF signals in networks based on subcarrier multiplexed schemes.


2018 ◽  
Vol 7 (3.29) ◽  
pp. 220
Author(s):  
Sivasindhu M ◽  
P Samundiswary

In future, the telecommunication systems will be totally based upon the photonic integrated circuits and components for the transmission of optical signals. Since optical signals offer high speed, less delay and higher efficiency. This introduces a new research area for photonic crystal based optical components like optical switch, multiplexer, optical filters etc. Among these devices, the optical switch draws more attention due to its primary switching operation. Hence, this paper deals with the modified design structure of GaAs photonic crystal based directional coupler all optical switch which operates at the wavelength of 1300nm. Further the switching performance evaluation of this device is made for both electro optic effect and non-linear optical effect. The design and simulation of the optical switch is done through Comsol Multiphysics software.   


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hamed Azhdari ◽  
Sahel Javahernia

Abstract Increasing the speed of operation in all optical signal processing is very important. For reaching this goal one needs high speed optical devices. Optical half adders are one of the important building blocks required in optical processing. In this paper an optical half adder was proposed by combining nonlinear photonic crystal ring resonators with optical waveguides. Finite difference time domain method wase used for simulating the final structure. The simulation results confirmed that the rise time for the proposed structure is about 1 ps.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Sicong Wang ◽  
Chen Wei ◽  
Yuanhua Feng ◽  
Hongkun Cao ◽  
Wenzhe Li ◽  
...  

AbstractAlthough photonics presents the fastest and most energy-efficient method of data transfer, magnetism still offers the cheapest and most natural way to store data. The ultrafast and energy-efficient optical control of magnetism is presently a missing technological link that prevents us from reaching the next evolution in information processing. The discovery of all-optical magnetization reversal in GdFeCo with the help of 100 fs laser pulses has further aroused intense interest in this compelling problem. Although the applicability of this approach to high-speed data processing depends vitally on the maximum repetition rate of the switching, the latter remains virtually unknown. Here we experimentally unveil the ultimate frequency of repetitive all-optical magnetization reversal through time-resolved studies of the dual-shot magnetization dynamics in Gd27Fe63.87Co9.13. Varying the intensities of the shots and the shot-to-shot separation, we reveal the conditions for ultrafast writing and the fastest possible restoration of magnetic bits. It is shown that although magnetic writing launched by the first shot is completed after 100 ps, a reliable rewriting of the bit by the second shot requires separating the shots by at least 300 ps. Using two shots partially overlapping in space and minimally separated by 300 ps, we demonstrate an approach for GHz magnetic writing that can be scaled down to sizes below the diffraction limit.


Author(s):  
P. Guan ◽  
K. M. Røge ◽  
H. C. H. Mulvad ◽  
M. Galili ◽  
H. Hu ◽  
...  

2008 ◽  
Vol 17 (03) ◽  
pp. 315-328 ◽  
Author(s):  
TANAY CHATTOPADHYAY ◽  
GOUTAM KUMAR MAITY ◽  
JITENDRA NATH ROY

Nonlinear optics has been of increased interest for all-optical signal, data and image processing in high speed photonic networks. The application of multi-valued (nonbinary) digital signals can provide considerable relief in transmission, storage and processing of a large amount of information in digital signal processing. Here, we propose the design of an all-optical system for some basic tri-state logic operations (trinary OR, trinary AND, trinary XOR, Inverter, Truth detector, False detector) which exploits the polarization properties of light. Nonlinear material based optical switch can play an important role. Tri-state logic can play a significant role towards carry and borrow free arithmetic operations. The principles and possibilities of the design of nonlinear material based tri-state logic circuits are proposed and described.


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