Simulation Of Optical Systems Research Articles

Next Generation of High-Speed Optical Communications Networks Using OFDM Technology

The usage of data transmission through Optical Fiber is highly preferred in every area where transferring of data is needed from one end to another. Moreover, nowadays the infrastructure of telecommunications is in good shape and size to handle data transmission through its optical fibers which have low attenuation and higher bandwidth. The seeking of data rate higher than 100Gbit/second and above has been increased to build it in urban and rural areas, and for long and short hauls. Consequently, the current goal is to propel this transmission system into the next appropriated level to avoid any decline of the optical infrastructure than its current capacity. To fulfill increased demand for bandwidth in Broadband services one of the most trusted technology is the Orthogonal Frequency Division Multiplexing (OFDM). The Orthogonal Frequency Division Multiplexing has been placed on-demand in optical communication, it is used in Long haul transmission Format in Direct and Coherent detection. OFDM has many features and abilities can boost the optical fiber performance by eliminating several limits of conventional Optical Fiber communication. OFDMA has polarization mode dispersion (PMD) and chromatic dispersion (CD) which are considered a big addition to the current systems. In addition to that, the easy correlation of the coherent optical OFDM with Wavelength Division Multiplexing (WDM) systems can further advantages in the transmission system such as super bandwidth, high spectral efficiency, and extra data rates. Furthermore, the WDM systems can improve data rate and capacity by using multiple wavelengths over a single fiber. This work aims to bring implementation and to perform a deep-dive study of higher data rates using Direct and Coherent Optical OFDM for long path transmissions. This research starts with a unique user and then extends to the add the OFDM - WDM system to get a data rate of 100 Gbps. Regarding the software portion, the Optisystem simulation tool was used for the design and implementation of the system. Moreover, the modulation type used is QAM for the OFDM signal, and I/Q modulation is deployed, while Coherent and Direct detection is used at the receiving portion. Q Factor, the bit error rate and eye diagram were discussed to study the System’s Performance and Quality. This work found CD-OOFDM is the best system for next generation of optical. The work compared WDM CD-OOFDM with SMF-DCF to DD and CD-OOFDM. In addition to that, it compared WDM CD-OOFDM with SMF-DCF to CD-OODFM with SMF. Therefore, the results showed that WDM CD-OOFDM with SMF-DCF achieved 25 Gbps for four channels of the WDM system at 120km channel, where the carrier frequencies were from 193.05THz to 193.2THz.

Beam characterization by phase retrieval solving the transport-of-intensity-equation.

A new method for the characterization of coherent laser beams is proposed. It is based on the non-iterative solution of the transport-of-intensity-equation. The phase to recover is decomposed into paraxial properties of laser beams and a set of lateral shifted radial basis functions, which allows for the derivation of a direct solution of the phase by a least-squares fit without the need of an initial guess. The method is tested with synthetic data to deduce an accuracy metric. Additionally, two real laser beams are characterized. Including the real light source in terms of the reconstructed field allows for a more holistic simulation of optical systems.

Comparison of coherent optical transmission systems performance by DP-QAM levels

In this paper, we investigated the Coherent Optical Transmission System (COTS) performance for multiple types of DP-QAM levels considering various CW laser input power. We compared the performance of COTS for 100 Gb/s with DP-32QAM, DP-64QAM and DP-128QAM respectively. We also inspected the relationship among Optical Signal to Noise Ratio (OSNR), Error Vector Magnitude (EVM) and Bit Error Rate (BER) which are found in accordance for both simulation curves and constellation diagrams. Results are obtained by experiments with DP-32QAM, DP-64QAM and DP-128QAM modulations techniques at symbol rate of 10 Gsymbol/s, 8.33 Gsymbol/s and 7.142 Gsymbol/s respectively. This work is completely based on simulation in Optisystem simulation setup.

External Switching Dynamics of Optical Bistability System Simulation

In this work, the external switching dynamics of a Fabry-Perot etalon are studied via optical bistability system simulation. The simulated set-up of this investigation consists of two laser beams; the first beam is continuous (CW) which is considered as a biasing beam and capable of holding the bistable system for a certain range, which we are interested in, from a point that is very close self-switching to a point where the switching is unachievable. The second beam is modulated by passing the first beam through an acousto-optic modulator (AOM) to produce pulses with a minimum rise time and is used as an external source (coherent switching). In this work, we obtained the optical bistable loops by applying absorption coefficient (α) = 20cm-1, e sample etalon thickness (D) = 110μm, forward mirror reflectivity (Rf) = 0.6, and backward mirror reflectivity (Rb) = 0.95. The steady state characteristic of an initial detuning of the cavity (φ0) = 0.8 was studied at the conditions of no external input pulse intensity (M(t) = 0) and switching that takes place at Is(ON)= 0.57mW and Is(OFF) = 0.4mW.

Sensor-Realistic Simulations for Evaluation and Planning of Optical Measurement Systems With an Application to Laser Triangulation

Image acquisition plays a central role in optical measurement systems. To configure machine vision setups, engineers often go through some empirical best practices to evaluate the measurement in different geometrical and optical configurations. This approach turns out to be expensive, tedious, and sometimes even unsuitable for nontrivial tasks. To automate this process, realistic synthetic images allow us to evaluate and optimize imaging setups without employing physical parts and sensors. Available computer graphics rendering techniques can be very beneficial for realistic simulation of images in machine vision systems. Simulating optical measurement systems, however, requires taking extra simulation components into account, including the wave optics effects and realistic spectral response and stochastic noise of the digital sensor. In this article, we focus on physical simulation of optical measurement systems and further propose and verify a sensor-realistic simulation framework for this purpose. We demonstrate the results in different steps for a laser triangulation measurement system, and verify them against experimental images, both qualitatively and quantitatively. The measurement with a laser light source results in wave optics effects which cannot be modeled by conventional ray-tracing methods. The concepts of this article are, however, general to many optical systems with both coherent and/or incoherent light sources. The agreement of simulations with reality is a promising proof of concept for machine vision experts, to move towards automating the setup planning process by means of sensor-realistic simulations.

Improved transmission length in the presences of ambient noise and scintillation effect using duobinary modulation in 40 Gbps free space optical channel

AbstractFree space optical (FSO) communication has gained significant popularity in recent years due to large bandwidth, license‐free spectrum, high data rates, less power consumption, and low mass requirements. However, system performance strongly depends on atmospheric conditions and ambient noise. In this letter, the duobinary modulation technique is applied and the system performance is investigated in the presence of ambient noise. The system is evaluated on the basis of Q‐factor, eye diagram, input power, transmission distance, and bit error rate. A significant improvement is observed in the presence of noise while using duobinary modulation. This study exploits extensive simulations to investigate the performance of the system. All simulations are performed for a single link of FSO communication network having a data rate of 40 Gbps in the Optisystem simulator and ambient noise is created using LEDs. After the exhaustive set of simulations, a significant improvement in transmission length is observed. It is also observed that at low input power, doubinary modulation provides better results when compared with on‐off keying (OOK) format. Scintillation effect has also be observed for doubinary modulation and compared with OOK modulation format. It is concluded that doubinary modulation provides better results in the presence of low and moderate scintillation.

Performance Analysis of Visible Light Communication (Vlc) with and Without Consider the External Noise Using Mach Zehnder (Mz) Modulator

Visible light communication is a high-speed developing technique with LEDs for both lighting and data communication. In this paper, examined the visible light communication performance over Mach Zehnder Modulation via Optisystem simulation tool. Quality factor and BER values of different link distance are predicted by optisystem simulation tool. The planned system can support 5 Gbps data rate up to 50 meter of link distance with a Quality factor of 15.71 for without any external noise interruption. In the case of external noise influence, the planned VLC system performance is also investigated through simulation tool. Consider the external noise interruption, the designed system can support 2Gbps data rate up to 20-meter link distance of Quality factor of 11.935. Quality factor for the system without any external noise influence is better compared to the system with external noise influence.

Simulation Study of DP-QPSK Coherent Detection Transmission System Based on Optisystem

Dual polarization quadrature phase shift keying (DP-QPSK) is currently the main modulation format for high-speed optical fiber communications, and its simulation modeling has important implications for theoretical research and practical applications. Based on Optisystem 15 optical communication system simulation software, this paper builds a 100 Gbit/s rate DP-QPSK modulation format coherent optical transmission system simulation model, analyzes the working principles of the transmitting end, transmission link, and coherent receiver. The principle of signal recovery at the digital signal processing end is briefly explained. The simulation results show that the signal quality after DSP processing has been significantly improved.

Optical system design and simulation of a wide-area fundus camera

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Design and simulation of optical system for novel LED solar simulator

针对现有LED太阳模拟器同时解决准直性、辐照度均匀性、光谱匹配性三大技术指标的难度较高的问题，基于光电一体化二次光学设计，提出一种简便、高效且可实现大功率的LED太阳模拟器光学系统设计方法。采用小角度准直透镜和抛物面镜来整合光源，通过混光棒和微结构进行匀光，最后利用抛物面镜实现光线的准直输出，基于同轴准直的设计思想完成LED太阳模拟器的设计。利用光学软件LightTools对LED太阳模拟器光学系统进行模拟仿真与分析优化，实验结果表明：在直径为260 mm的有效辐照面上辐照不均匀度为2.5%、准直角为1.5°。

Design analysis and performance evaluation of the WDM integration with CO-OFDM system for radio over fiber System

<span>The optical communication and wireless networks can be integrated to increase the capacity and mobility with decrease the costs in the access networks. Optical communication is considered a Fiber optic communication that can be used for wired and wireless communication. The problems of Fiber optic communication have a solution represented by Radio over fiber (RoF) which can control many base stations (BSs) that connect to a central station (CS) with an optical fiber. The Coherent optical OFDM (CO-OFDM) have concerned a great interest due to the high spectral efficiency and strength to the fiber dispersion, also it can be considered as a promising candidate when used in long haul optical fiber transmission systems. The integration of the wavelength division multiplexing system (WDM) with (CO-OFDM) system for increasing the system performance as well as achieving high data rates. The simulation of WDM-ROF and (WDM-CO-OFDM) with an optisystem simulator to analyze the RF spectrum, spectrum signal visualizers, and constellation diagrams. The proposed of integration of WDM and RoF-OFDM system is to achieve 100 km fiber length using 4QAM sequence bit, and the received power with electrical and optical amplifications by using 10 Gbps data signal.</span>

Performance Analysis of Q Factor Optical Communication in Free Space Optics and Single Mode Fiber

Developments in the technology sector are currently experiencing rapid progress, especially in data transmission technology. The increasing need for fast data traffic in the telecommunications sector requires technology that can send data quickly. Optical fiber has the speed of receiving and sending data at 2.5 Gbps while FSO has a speed of up to 100 Gbps but this depends on Wavelength, the modulation technique used and the distance of the telescope between the transmitter and receiver. The speed of receiving and sending data also depends on the Quality (Q) of the signal, the greater the value of Quality (Q) of the signal, the better the Quality of the signal. FSO is an optical communication system that uses the atmosphere as its propagation medium and Optical Fiber uses silica as its propagation medium. Therefore, in this paper, a performance analysis of Free Space Optics (FSO) and Single Mode Fiber is carried out based on the Quality Factor and Bit Error Rate (BER) of a signal that is carried out using Optical System simulations with a wavelength of 1310 nm, 1380 nm, 1550 nm, 1550 nm and 1560 nm, with 1 km, 3 km and 5 km, respectively. Then, analysis uses an Eye Diagram to analyze the output signal and compare the Factor Q and Bit Rate Error (BER).

Certain Investigation on Visible Light Communication with OFDM Modulated White LED Using Optisystem Simulation

Visible light communication (VLC) has drawn more attention in recent years. It is due to the reason that the existing light sources for lighting application in home, office and streets have huge amount of bandwidth and they can deliver data communication at higher bit rates. Orthogonal frequency division multiplexing (OFDM) modulation has also significant impact on communication sector now-a-days due to its healthiness to the signal distortion and support for higher data rate. In this paper we have studied the VLC system using Optisystem simulation tool for an already practically measured free space channel. White LED is used as source for our VLC system and it is driven by OFDM modulated signal. The arrangement of this system is analysed for various bit rates and link ranges. The proposed system can support 10 Gbps data rate up to 2 m link range. We have also studied the OFDM subcarrier impact on system performance and link range. The performance of designed system is compared based on its BER and constellation diagram.

Simulation and analysis of optical imaging systems including real freeform components

Abstract In recent years, the precision of the manufacturing process for optical surfaces has improved tremendously. As a result, freefrom surfaces have become more attractive options for imaging applications with increased accuracy requirements. However, with regards the integration into an optical system, performance is often limited due to surface imperfections, such as mid-spatial frequency errors and alignment errors. This demonstrates the need for a more holistic description of systems, including multiple freeform components, which enable performance predictions based on the system as a whole. In this work, a solution for such a simulation is presented and verified by a comparison with the experimental data. This procedure not only predicts system performance but also supports tolerancing and easier alignment.

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.

Deep Neural Network Based Chromatic Dispersion Estimation With Ultra-Low Sampling Rate for Optical Fiber Communication Systems

Fast and low-cost chromatic dispersion (CD) estimation is very important for fiber link that is dynamically reconfigurable in the next-generation optical networks. In this paper, a novel CD estimation method based on the deep neural network (DNN) with ultra-low sampling rate is proposed for the optical fiber transmission systems. The method can estimate CD for under-sampled signals by the trained DNN with a weighted average. To demonstrate the feasibility of the method, the simulation of a 28-GBaud five-channel optical fiber transmission system with 100–2000-km SSMF transmission is carried, where the sampling rate of the analog-to-digital converter (ADC) at the receiver is only 500 MHz. The results show that the maximum mean absolute error (MAE) of the estimated CD is less than 75 ps/nm with the reference cumulative CD from 1600 to 32000 ps/nm for QPSK and 16QAM signals. Meanwhile, the robustness of the proposed method is verified for amplifier spontaneous emission (ASE) and nonlinear (NL) noise. Furthermore, we experimentally demonstrated that the maximum MAE is less than 75 ps/nm when the transmission distance varies from 100 to 800 km in 20-GBaud QPSK optical fiber transmission system. In conclusion, the proposed DNN-based CD estimation method shows great potential for the cost-effective under-sampled systems.

Свойства временных оптических солитонов в оптических волокнах и возможность их использования в телекоммуникациях. Часть 4

In the fourth part of the paper, a theoretical study of the processes of propagation of pulses having the form of Gaussian functions and hyperbolic secant on a single-mode optical fibers with alternating signs of group velocity dispersions and taking into account losses was performed. Fundamental inaccuracies in widely used expressions to describe the processes of propagation of Gaussian pulses through optical fibers are revealed and refined analytical expressions are proposed. The paper contains a simulation of optical fiber communication systems at speeds of 10 and 40 Gbit/s using the OptiSystem and AltPhotonic Simulation Tool programs. The influence of the chirping value on the quality of communication is investigated. A comparison of fiber-optic communication systems using concentrated and distributed optical amplifiers is performed. Engineering formulas and recommendations for designing quasi-soliton optical fiber communication systems are proposed.

Design and simulation of optical system for novel LED solar simulator

针对现有LED太阳模拟器同时解决准直性、辐照度均匀性、光谱匹配性三大技术指标的难度较高的问题，基于光电一体化二次光学设计，提出一种简便、高效且可实现大功率的LED太阳模拟器光学系统设计方法。采用小角度准直透镜和抛物面镜来整合光源，通过混光棒和微结构进行匀光，最后利用抛物面镜实现光线的准直输出，基于同轴准直的设计思想完成LED太阳模拟器的设计。利用光学软件LightTools对LED太阳模拟器光学系统进行模拟仿真与分析优化，实验结果表明：在直径为260 mm的有效辐照面上辐照不均匀度为2.5%、准直角为1.5°。

Two-dimension trapezoidal grating raytracing based on the scalar diffraction and scattering theory

Diffraction grating is a fundamental optical element in spectral measurement or source monochromation. A newly designed grating named as two-dimension trapezoidal grating (TG), which not only has non-harmonic diffraction, non-background contaminations, but also has high absolute diffraction efficiency and easy fabrication, was proposed, recently. However, its applications in spectral measurement or source monochromation are limited as its diffraction pattern is more complex than ordinary grating and there is no raytracing simulation tool to effectively analyze and evaluate the property of an optical system with TG. A raytracing model for TG based on the scalar diffraction and scattering theory is proposed to solve the above problem. Diffraction direction and absolute efficiency of each diffraction order are obtained by using mathematical derivation with scattering theory and scalar diffraction theory, respectively, which are the key parts of TG’s raytracing model. Once TG’s raytracing module is added into the optical simulation tool, X-LAB, it offers a new opportunity for design and numerical simulation of optical systems with a TG.

Research on the Performance of 40 Gbps UV Communication System Based on DWDM

Due to the atmospheric transmission attenuation, the rate of UV communication is low and range is limited at present. According to the idea of DWDM in optical fiber communication, we proposed a 40 Gbps UV communication scheme, which has 8 channels in total. The transmission rate of each channel is 5 Gbps. And its performance was simulated by the optical communication system simulation design software which is called OptiSystem. Simulation analysis shows that the maximum transmission distance of the designed system is up to 1200 meters under the transmission rate of 40 Gbps without any compensation scheme. On the 280nm channel, the minimum error rate and Q factor are 1.56−14 and 7.59201 at 1 km respectively. When the transmission distance reaches 1.5 kilometers, the bit error rate becomes very high and the communication effect is very poor. The simulation results can provide reference for the design of UV communication system.