Optical Code Research Articles

Design and Implementation of Two-Dimensional Enhanced Multi-diagonal Code for High Cardinality OCDMA-PON

This paper proposes the design of a novel two-dimensional enhanced multi-diagonal (2D-EMD) code along with the implementation of corresponding architecture for incoherent optical code division multiple access passive optical network (OCDMA-PON). The proposed algorithm is derived by using spatial coding as second dimension in the existing 1D-EMD code to elevate orthogonality within adjacent codes and minimize the interference of subscribers simultaneously accessing the medium. Performance of the proposed 2D-EMD OCDMA system is analyzed through Gaussian approximation and simulation analysis for an agreeable bit error rate (BER) of $$10^{-9}$$ . Analytic analysis shows that the proposed 2D-EMD OCDMA system support more subscribers in comparison with existing systems based on 2D diluted-perfect difference (2D-DPD) and diagonal eigenvalue unity (DEU) codes. Cardinality of the proposed setup surpasses 2D-DPD and 2D-DEU by 5 and 1.8 times for an acceptable BER of $$10^{-9}$$ . Moreover, the optimal communication requirement is satisfied by 2D-EMD system with lowest effective source power of $$-27$$ dBm at 622 Mbps of data. Simulation analysis through a highly recognized software called Optisystem also validates the mathematical analysis and shows that the proposed system can accommodate large number of subscribers at high data rates. Both analytical and simulation analysis proves that the proposed system is able to support next generation PONs.

Analysis of noise suppression for OCDMA systems with fixed in-phase cross-correlation codes and single O/E converter

Performance of the non-coherent spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems is primarily degraded by the presence of noise sources generated during the process of optical-to-electrical (O/E) conversion at the receiving photodiode (PD). Phase induced intensity noise (PIIN) is generated by limitations in the coding scheme that leads to the mixing of adjacent spectrum's commonly known as multiple access interference (MAI). While, shot and thermal noise sources are generated at PD during the conversion of signal from O/E domain for further processing. This paper investigates and compares the performance of two detection techniques with reference to the received power units and suppression of noise sources while recovering and decoding enhanced multi diagonal (EMD) code. Both techniques namely spectral direct detection (SDD) and single PD detection (SPD) use one PD for O/E conversion to reduce the effect of shot and thermal noise. Numerical analysis using Gaussian approximation shows that SPD technique provides better performance for an acceptable bit error rate (BER) of 10−9 as compared with SDD technique, due to maximum recovery of power units in the received spectrum. Simulation analysis through a highly recognized software called Optisystem also validates the mathematical formalism and shows the EMD and SPD based SAC-OCDMA system is able to support 64 subscribers communication simultaneously beyond 1 Gbps of data while −10 dBm power is maintained at the receiving PD.

Nanotriangle-based gap-enhanced Raman tags for bioimaging and photothermal therapy

Surface-enhanced Raman scattering (SERS) nanoparticles can be utilized as optical labeling nanoprobes for bioimaging with advantages of the fingerprint vibrational signal as a unique optical code and the ultra-narrow linewidth for multiplexing. As a new type of SERS nanoprobes, gap-enhanced Raman tags (GERTs) developed recently can overcome the common issues of poor photostability and limited Raman enhancement. In this work, we have constructed bright nanotriangle-based GERTs (NT-GERTs) for combined SERS bioimaging and photothermal therapy. With optimized Au shell morphology and thickness, NT-GERTs possess 20 folds brighter SERS signal and a more efficient photothermal effect compared to conventional nanosphere-based GERTs. These NT-GERTs show great potential for intraoperative SERS bioimaging guided photothermal therapy of cancers.

Simulation of time-spreading wavelength-hopping OCDMA systems

This paper analyzes the performance of the traditional and balanced time-spreading wavelength-hopping (TW) optical code division multiple access (OCDMA) receivers associated with their appropriate codes. Several 2-D TW codes with different properties are simulated in this work. The experimental simulations are implemented by Optisystem software to demonstrate the performance of a three-user OCDMA system operating at 10 Gb/s. The simulation results reveal that the traditional receiver employing zero cross-correlation (ZCC) codes has better performance if compared to the balanced scheme. In addition, for ZCC codes, the assigned wavelengths to each user highly affect the system performance.

Performance analysis of spectral/spatial of OCDMA system using 2D hybrid ZCC/MD code

This paper proposes a new spectral/spatial code for Spectral Amplitude Coding in Optical Coding Division Multiple Access (SAC-OCDMA) called two-Dimensional hybrid ZCC/MD code. The new code combines two of the one –dimensional codes which are Zero Cross Correlation (1D ZCC) and Multi-Diagonal code (1D MD). Moreover, it produces a zero cross correlation property for each code. The main goal of this proposed code is to mitigate Phase Induced Intensity Noise and eliminate Multiple Access Interference (MAI). This proposed code can provide a better performance comparing to other codes as 2D FCC/MDW and 2D DPDC according to the obtained numerical analysis.

Performance enhancement of OCDMA system based on sequential algorithm (SeQ) Code

<span>This paper presents a new class of Sequential Algorithm (SeQ) code for Optical Code Division Multiple Access (OCDMA) system. The SeQ code has advantages of various cross – correlation property at any given number of users, and code weights. The result shown, at error floor BER = 10-09, the SeQ code capability to support 190 numbers of simultaneous users was higher than those achieved by FCC (W=4), DCS (W=4) and MFH (W=4). SeQ code excellently support 190 number of users due to due to the arrangement of code algorithm and flexibility cross-correlation (0 and 1) role. In addition, SeQ code capable to support up to 70 km for bit rate 155 Mbps in comparison 622 Mbps, 1 Gbps, and 2 Gbps be able to support 40km, 30km and 20km respectively. Hence, we can ascertain that PIIN and MAI are successfully eliminated for SAC-OCDMA coding system.</span>

N-dimensional optical orthogonal codes, bounds and optimal constructions

We generalized to higher dimensions the notions of optical orthogonal codes. We establish uper bounds on the capacity of general $ n $-dimensional OOCs, and on specific types of ideal codes (codes with zero off-peak autocorrelation). The bounds are based on the Johnson bound, and subsume many of the bounds that are typically applied to codes of dimension three or less. We also present two new constructions of ideal codes; one furnishes an infinite family of optimal codes for each dimension $ n\ge 2 $, and another which provides an asymptotically optimal family for each dimension $ n\ge 2 $. The constructions presented are based on certain point-sets in finite projective spaces of dimension $k$ over $GF(q)$ denoted $PG(k,q)$.

Cost-effective fiber fault monitoring using MLMW-OOCs in high-capacity PONs considering user geographical distribution

Cost-effective monitoring of in-service passive optical network (PON) link is becoming increasing important for network operators. Recently, optical coding schemes based on 1D-PCs or 2D-OOCs for PON link monitoring have been proposed. Note that these codes are equal-length, and are assigned randomly to each user in PON. Hence there may be severe interferences, especially in the case that user separation length is close to each other. Moreover, when the number of users (i.e., user network size) is larger, the code length becomes abnormally large, which makes these existing schemes infeasible in practice. In this paper, we propose a novel codeword assignment scheme based on multiple-length multiple-wavelength optical orthogonal codes (MLMW-OOCs) for realistic PON link fault monitoring. In the novel codeword assignment, the information on user geographical distribution is additionally considered to minimize the inter-user interferences. The mathematical expressions of system signal-to-interference-ratio (SIR) are analyzed with aid of a new parameter “interference ratio”. The extensive simulation results show that the SIR of the MLMW-OOC-based scheme performs better than that of the 2D-OOCs scheme. Moreover, our proposed scheme can support the effective monitoring for high-capacity PONs with the shorter code length, the smaller correlation distance, and hence present the higher system SIR performances.

Underwater optical wireless sensor networks using resource allocation

Optical wireless communications is an energy efficient and cost-effective solution for high speed and high secure wireless connections. In this paper, we propose an underwater optical wireless sensor network using multiple input multiple output technique and power allocation algorithm for supporting multiple users with the impacts of underwater channel uncertainty interferences. In proposed power allocation algorithm, all the LED nodes in are coordinated and controlled by a central controller; each LED node supports all the users within its field of view. To separate users, optical code division multiple access is used; cyclic optical orthogonal code working as CDMA code is employed. At the receiver, a minimal mean squared error (MMSE) filter is uniquely designed for each user. The MMSE filters and the assigned power can be jointly optimized to improve the overall throughput and signal to noise ratio. Since the system performance may be impacted by the underwater channel uncertainty, the proposed power allocation can use the predicted channel uncertainty variance to reduce the interference of the channel uncertainty and improve the signal to noise ratio. Compared to the equal power allocation algorithm, the proposed algorithm can support longer transmission distance, higher bit rate and lower bit error rate.

Design and Investigation on Image Transmission in Multi-User Cross-Layer Security Network

A multi-user cross-layer security network based on optical code division multiple access (OCDMA) and algorithmic cryptography is proposed, and its security performance is analyzed quantitatively for the first time. In this scheme, eavesdroppers have to not only intercept the optical code of OCDMA in physical-layer, but also break the algorithmic cryptography in data-layer. Thus, the information security will be enhanced effectively. Synchronous transmission system and asynchronous transmission system are analyzed respectively. It can be seen that the cross-layer security of asynchronous transmission is far greater than that of synchronous transmission when the number of users is large enough. OptiSystem simulation is used to investigate the image transmission in cross-layer security system. The transmission distance of single mode fiber is 100 km, and transmission rates are 10 Gbit/s and 1 Gbit/s respectively. It can be seen that legitimate user can recover original image correctly with matched decoder and correct encryption algorithm. However, eavesdroppers cannot recover the image correctly with matched decoder/wrong encryption algorithm or unmatched decoder/correct encryption algorithm. Therefore, our scheme can greatly enhance the security of image transmission system.

Constructions of optimal balanced $ (m, n, \{4, 5\}, 1) $-OOSPCs

Kitayama proposed a novel OCDMA (called spatial CDMA) for parallel transmission of 2-D images through multicore fiber. Optical orthogonal signature pattern codes (OOSPCs) play an important role in this CDMA network. Multiple-weight (MW) optical orthogonal signature pattern code (OOSPC) was introduced by Kwong and Yang for 2-D image transmission in multicore-fiber optical code-division multiple-access (OCDMA) networks with multiple quality of services (QoS) requirements. Some results had been done on optimal balanced \begin{document}$ (m, n, \{3, 4\}, 1) $\end{document} -OOSPCs. In this paper, it is proved that there exist optimal balanced \begin{document}$ (2u, 16v, \{4, 5\}, 1) $\end{document} -OOSPCs for odd integers \begin{document}$ u\geq 1 $\end{document} , \begin{document}$ v\geq 1 $\end{document} .

可见光通信非对称限幅光多载波码分多址系统的设计及性能分析

可见光通信非对称限幅光多载波码分多址系统的设计及性能分析

High-efficiency DBA-BOTDA with optimized SNR by multiple bandwidths pump modulation

For Brillouin optical time-domain analysis (BOTDA) based on distributed Brillouin amplification (DBA), constant Brillouin response achieved by the exponentially variable bandwidth/intensity pump modulation suffers from the much lower pumping efficiency for long-range sensing, which counterbalances the merit of DBA. In this Letter, pump modulation by multiple constant bandwidths was proposed and demonstrated. The ∼98.9 km sensing with ∼5 m spatial resolution and no use of optical pulse coding (OPC) was achieved by ∼8 dBm Brillouin pump, which is lower by ∼9 dB in theory by comparison with exponentially increased bandwidth modulation. Compared with traditional DBA-BOTDA, signal-to-noise ratio (SNR) enhancement with >4.6 dB was obtained. The flattened standard deviation (STD) of Brillouin frequency shift (BFS) (less than ∼2 MHz) along the whole fiber was demonstrated.

Further results on optimal $ (n, \{3, 4, 5\}, \Lambda_a, 1, Q) $-OOCs

Let $ W = \{w_1, w_2, \cdots, w_r\} $ be a set of $ r $ integers greater than 1, $ \Lambda_a = (\lambda_a^{(1)}, \lambda_a^{(2)}, \cdots, \lambda_a^{(r)}) $ be an $ r $-tuple of positive integers, $ \lambda_c $ be a positive integer, and $ Q = (q_1, q_2, \cdots, q_r) $ be an $ r $-tuple of positive rational numbers whose sum is 1. Variable-weight optical orthogonal code ($ (n, W, \Lambda_a, \lambda_c, Q) $-OOC) was introduced by Yang for multimedia optical CDMA systems with multiple quality of service requirements. In this paper, tight upper bounds on the maximum code size of $ (n, \{3, 4, 5\}, \Lambda_a, 1, Q) $-OOCs are obtained, and infinite classes of optimal $ (n, \{3, 4, 5\}, \Lambda_a, 1, Q) $-OOCs are constructed.

DWDM混合光学系统中帧间和信道内四波混频效应的抑制

In this study, a hybrid system of optical Code Division Multiple Access(optical CDMA) and Dense Wavelength Division Multiplexing(DWDM) is proposed with a comprehensive investigation into the effect of four-wave mixing(FWM). In such system, two major FWM problems exist, inter and intra-channel FWM, including multiple access interference(MAI) and inter-symbol interference(ISI). Results show that the optimum transmitted power is 18dBm in order to control the trade-off between inter and intra-channel FWM, where an increase in the BER of the hybrid system at transmitted power above 18 dBm is indicated. Hence, an electro-optic phase modulator(EOPM) module is proposed and placed after the WDM multiplexer to simultaneously modulate the phase of all wavelengths signals to increase the nonlinear tolerance in the hybrid system by suppressing the impact of intra-channel FWM, which is shown to greatly improve the performance of the optical CDMA-DWDM hybrid system based OOK transmission. In addition, the effect of MAI can be reduced by the use of multi-diagonal(MD) identification sequence code, due to the zero cross-correlation property of MD. The results also reveal that the CDMA technology in conjunction with chromatic dispersion helps to reduce the effect of inter-channel FWM. Moreover, the identification sequence code interval plays crucial role in the mitigating of ISI as the results expose that the best performance of the proposed hybrid system can be achieved when the identification sequence code interval squeezed into 25% of bit duration where the avoidance of ISI is guaranteed.

10 Gb/s two-dimensional free-space optical code division multiple access wiretap channel with spatial diversity

We experimentally demonstrate a 10 Gb/s free-space optical wiretap channel based on a spatial-diversity scheme and optical code division multiple access. In weak and middle turbulence cases, the bit error rate of a legitimate user can be decreased, and physical layer security can be simultaneously enhanced.

Performance characteristics of the spectral-amplitude-coding optical CDMA system based on one-dimensional optical codes and a multi-array laser

Performance characteristics of the spectral-amplitude-coding optical CDMA system based on one-dimensional optical codes and a multi-array laser

Optical Code Division Multiple Access for FTTH system

Many multiple access techniques have been proposed and demonstrated to provide flexible solutions for FTTH network configurations. The performance of this system suffers because of the correlation properties that contribute to a high level of Multiple Access Interference (MAI), low system capacity (users), and lower transmission rate. In this paper, we have proposed Optical CDMA (OCDMA) as a configuration solution for FTTH networks to improve the performance of this type of network. Full Text: PDF References. Z. Mateusz, M. Mariusz, On cost of the uniformity in FTTH network design, Conference on Transparent Optical Networks (2017), 87-90 CrossRef CEDRIC F. LAM, Passive Optical Networks- Principles and Practice, first ed., British Library, USA, 2007. DirectLink M.K. Abdullah, W.T. P'ng, P.W. Lau, E.R. Tee, FTTH access network protection using a switch, Asia Pacific Conference on Communications (APCC), 3(2003) 1219–1222. CrossRef J. Ronnakorn, S. Napat, L. Somkiat, Design and implement of GPON-FTTH network for residential condominium, Conference on Computer Science and Software Engineering, (2017), 333-339. CrossRef M. BOUREGAA, M. CHIKH-BLED, Comparative Study of Optical Unipolar Codes for Incoherent DS-OCDMA system, International Journal of Hybrid Information Technology, 6 (2013) 225-236. CrossRef M. BOUREGAA, M. CHIKH-BLED, The performance of a DS-OCDMA system using Orthogonal Optical Codes (OOC), European Scientific Journal, 9 (2013), 322-335 CrossRef M. Iwase, Y. Ishikawa, T. Komatsu, J. Kasahara, N. Hattori, M. Miura, N. Nakamura, K. Odaka, Optical transceiver modules for gigabit Ethernet PON FTTH systems, Furukawa Review, 28 (2005) 8-10. DirectLink

Mechanically Excited Multicolor Luminescence in Lanthanide Ions.

Mechanoluminescence (ML) featuring photon emission by mechanical stimuli is promising for applications such as stress sensing, display, and artificial skin. However, the progress of utilizing ML processes is constrained by the limited range of available ML emission spectra. Herein, a general strategy for expanding the emission of ML through the use of lanthanide emitters is reported. A lithium-assisted annealing method for effective incorporation of various lanthanide ions (e.g., Tb3+ , Eu3+ , Pr3+ , Sm3+ , Er3+ , Dy3+ , Ho3+ , Nd3+ , Tm3+ , and Yb3+ ) into CaZnOS crystals that are identified as one of the most efficient host materials for ML is developed. These doped CaZnOS crystals show efficient and tunable ML spanning full spectrum from violet to near infrared. The multicolor ML materials are used to create encrypted anticounterfeiting patterns, which produce spatially resolvable optical codes under single-point dynamic pressure of a ballpoint pen.

Performance Limits of FSO Based SAC-OCDMA System Under Weather Conditions

AbstractIn this paper, the Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) is investigated in Free Space Optics (FSO) using Zero Cross Correlation (ZCC) codes to evaluate its performance limits in terms of link range. The system is analyzed under clear, haze, moderate fog and dense fog weather conditions. This system has been evaluated numerically and by simulation analysis by maintaining the transmitted power at 10 dBm, for safety reason, according to International Telecommunication Union (ITU) and minimum acceptable BER of10{10}–9. The simulation results shown that the present system can transmit 622 Mbps/1 Gbps up to maximum link range of 1450 m/1100 m and 61 m/54 m under clear and dense fog conditions, respectively.