Figure 1 - uploaded by Ampalavanapillai Nirmalathas
Content may be subject to copyright.
Source publication
We demonstrate a simple, passive technique for significant improvement of transmission performance in fiber wireless links through the application of a narrow-band fiber Bragg grating. The grating is used to optimize the optical modulation depth in the transmitted signal by reducing the power of the optical carrier. We present experimental measurem...
Context in source publication
Context 1
... explosive growth of the Internet, and the success of 2G systems together with WLANs have had a profound impact on our perception of communication. First of all, the vast majority of users now believe in the new notion of ”always on” communication. We are now living in the era of ubiquitous connectivity or ”communication anytime, anywhere, and with anything”. Secondly, the concept of broadband communication has caught on very well. As fibre penetrates closer to the end-user environment (Fibre To The Home/Curb/X, FTTH/C/X), wired transmission speeds will continue to rise. Transmission speeds such at 100 Mbps (Fast Ethernet) are now beginning to reach homes. The demand to have this broadband capacity also wirelessly has put pressure on wireless communication systems to increase both their transmission capacity, as well as their coverage. In general there is a trade off between coverage and capacity. Figure 1.3 shows the relationship between some of the various standards (present and future), in terms of mobility (coverage), and capacity. For instance, the cell size of Wireless Personal Area Networks (WPANs) is typically a few metres (picocell), while their transmission rates may reach several tens of Mbps. On the other hand 2G (e.g. GSM), and 3G (e.g. Universal Mobile Telecommunication System (UMTS) and the International Mobile Telecommunications ...
Similar publications
Microwave switches, or Radio Frequency (RF) switches have been intensively used in microwave systems for signal routing. Compared with the fast development of microwave and wireless systems, RF switches have been underdeveloped particularly in terms of switching speed and operating bandwidth. In this paper, we propose a photonics based RF switch th...
Citations
... modifications inside the core of the fiber have led to the formation of many optical devices for sensing and communications purposes [3,4,5,6,7,8,9,10,11]. Although FBGs have been extensively used for different purposes, utilizing them to improve the optical transmission link performance has revolutionized the telecommunication industry [12,13,14,15,16,17]. Hence, nowadays, researchers are using cascaded FBG structures in optical communication systems to enhance its performance by reducing the spectral width of the laser source, thus reducing the dispersion [18,19]. ...
In this paper, an optical communication system constructed with cascaded fiber Bragg gratings or FBGs of varying lengths capable of operating in the C-band is presented. Here, initially, a passive optical device formed with four cascaded FBGs of varying lengths is proposed and analysed. Subsequently, the proposed device is kept in the optical communication system to reduce the spectral width
of the source, thereby enhancing the system's performance. Analytical formulation based on the transfer matrix method (TMM) of an optical device is incorporated. The effect of such a device on the system performance at various operating distances is discussed. Further, the system performance is studied with the apodized FBGs in the passive optical device. At the end, we investigated the effect of incorporating the cascaded FBG structure in the system utilizing four-level pulse amplitude modulation or PAM-4 modulation . As per the simulation results, the proposed device has given a maximum reflectivity of 98.39% and a minimum FWHM of 0.175 nm for uniform FBGs. But with the apodized FBGs, an FWHM of 0.07 nm with a reflectivity of 59.81% has been achieved. Simulation results reveal that the system formed with the proposed device has given better performance up to a distance of 105 km compared to the absence of the device. At the maximum operating distance of the system with apodized FBGs, the Q-factor and bit error rate (BER) are recorded as 6.712 and 9.5321×10-12, respectively. Apart from the Q-factor and BER estimation, eye height is also used to estimate the system performance at various operating distances.
... Transmission efficiency can be improved by either using a SCM [98] which suppresses the carrier (or) through optical filtering using FBG [100] or sub-picometer optical BPF [101] which allow frequencies in a certain range to propagate (or) through OIL [97] which generates an optical comb that allow specific frequencies to propagate, thus reducing up the power penalties. ...
Next generation wireless networks are the need of the hour with reliable, high bandwidth, low Bit Error Rate (BER), high Signal to Noise Ratio (SNR), large network capacity, etc. for a paradigm shift to all optical networks from the prevailing conventional electro optic network due to the various benefits of optical links such as enormous bandwidth and extremely low losses. This paper presents a primitive overview of the foregoing technologies and then move on to encapsulating the contemporary techniques to enhance the system performance. For this, preceding limitation and their respective improvement measures from literature of fiber communication and its integration with the next generation networks mainly based upon Radio over Fiber (RoF), Fiber to the Home (FTTH) and Free Space Optics (FSO) are discussed. The advancement in the domain of optical wireless communication utilizing various methodologies is summarized. Finally, we conclude by incorporating various cost reduction methodologies developed which may further be explored to make next generation networks more promising.
... An SSB-SC signal can be generated through I-Q modulation in dual-parallel (DP) MZMs formed by a main interferometer encompassing two MZMs onto each of its branches [10], or by standard DSB modulation followed by optical filtering [11] which is also suitable for SSB generation [11], [12]. In practical cases, it is desirable to adjust the carrier-to-sideband power ratio (CSR) for maximizing the received RF power, which can be realized with partial carrier suppression through optical filtering [13] or by precisely controlling the bias settings in DP-MZM [14]. SSB(-SC) signals generated through MZMs however generally exhibits low modulation levels due to the restricted linear region of the modulator, which might limit the sideband optical signal-to-noise ratio (SNR) as well as the received signal power. ...
A 5 Gbit/s single-sideband suppressed-carrier (SSB-SC) modulated signal is generated using a phase modulator (PM) and an integrated optical filter implemented with a third-order distributed feedback resonator (DFBR) in a silicon nanowire strip waveguide. Small in-band variations of the integrated filter group delay response have been measured.
The moderate impact of the filter phase on the generated SSBSC signal is also assessed by transmission over 60 km of standard single mode fiber, indicating an additional power
penalty of about 1 dB. A frequency shift of 20 GHz for the broadband modulated data is employed in this experimental demonstration. By filtering high-order harmonics from the PM and reinserting the optical carrier, the scheme can be potentially employed for generating SSB-modulated signals up to the mmwave band starting from a lower RF carrier. The proposed architecture is simple and stable, and suitable for realizing a
photonic integrated circuit in silicon-on-insulator technology with minimized footprint by monolithic integration of the DFBR filter with the PM.
... The radio-over-fiber (ROF) technology can provide huge transmission bandwidth and long transmission distance for mobile data communication, which is a hot topic in recent years [1][2][3][4][5][6]. For the practical implementation of the ROF technology, it is vital to generate optical millimeter-wave (mm-wave) signals with high performance, low cost and flexible modulation formats [7][8][9]. By using the external modulator, we can generate double-sideband (DSB) [7,[10][11][12][13][14][15][16][17], single-sideband (SSB) [7,9,[18][19][20][21][22] and optical-carrier-suppression (OCS) [7,16] mmwave signals. ...
We propose a new scheme to realize the independent dual single-sideband (SSB) vector millimeter-wave (mm-wave) signal generation based on one single in-phase/quadrature (I/Q) modulator. The two SSB vector mm-wave signals can have independent carrier frequencies and modulation formats. We experimentally demonstrate the simultaneous generation and transmission of 38 GHz 16-ary quadrature-amplitude-modulation (16QAM) and 40 GHz quadrature-phase-shift-keying (QPSK) mm-wave signals based on this scheme. The penalty of the 16QAM and QPSK mm-wave signals after transmission over 10-km standard single-mode fiber and 0.5-m wireless link can be neglected.
... Upon extending the delivery distance for the optical millimeter wave, SSB modulation is superior to DSB due to its reduced effects in suffering dispersion in a single-mode fiber (SMF), but the receiver reactivity for SSB is comparatively low due to the huge dc component at the central wavelength. A Fiber Bragg Grating (FBG) are used to conceal the dc component in order to improve the receiver sensitivity [10]. ...
Optical millimeter-wave signal generation in Radio over Fiber (RoF) based on external modulators using different modulation schemes such as Single-Sideband (SSB), Double-Sideband (DSB) are experimentally compared. The major fallout for external modulation scheme system performance to downgrade is due to dispersion and the fading effect in optical signal generation while generating high Bit Error Rate (BER) when involving long distance delivery. In this work, we proposed mm-wave signal utilize Stimulated Brillouin Scattering (SBS) scheme which indicates the best performance amongst the scheme based on simulation that it achieves to propagate longest of distance over fiber, highest receiver sensitivity, the lowest BER and coherence of Mach-Zehnder Modulator (MZM) extinction ratio. Mm-wave signal of 40 Ghz and 10 Gb/s data rate was generated with the plotting of eye diagram. © 2019 Institute of Advanced Engineering and Science. All rights reserved.
... A FBG has the advantages of simple structure, flexible operation, low loss, and low crosstalk. In addition, FBGs have been widely applied to optical fiber communication, fiber mode couplers, fiber lasers, fiber sensors, and fiber filters [8][9][10][11][12][13][14]. ...
We propose a vector mode conversion approach based on asymmetric fiber Bragg gratings (AFBGs) written in step-index fiber and vortex fiber, respectively. The mode coupling properties of AFBGs are numerically investigated. Compared to step-index fiber, the large mode separation in the vortex fiber is beneficial to extracting the desired vector mode at specific wavelengths. In addition, the polarization of incident light and the attenuation coefficient of index change distribution of the AFBG play critical roles in the mode coupling process. The proposed AFBG provides an efficient method to realize high-order vector mode conversion, and it shows great potential for orbital angular momentum multiplexing and fiber lasers with vortex beam output.
... Despite the numerous numerical calculations and simulations (see, e.g., [1,2]) the full analytical solution of the wave equation in the presence of a periodic modulation of the refractive index is still an open problem. In the last years, a large number of fiber Bragg gratings devices were developed for different types of applications, among others, for optical communications devices, tunable wavelength filters and temperature, and pressure sensors [3][4][5][6][7][8]. In the theoretical approaches proposed to study these systems, one has also to deal, besides of the spatial modulation of the refractive index, with model limitations and the finiteness of the actual Bragg systems. ...
We show that using the theory of finite periodic systems we obtain an improved approach to calculate transmission coefficients and transmission times of electromagnetic waves propagating through fiber Bragg gratings. We discuss similarities, advantages, and differences between this approach and the well known less accurate one coupled mode approximation and the pseudo-Floquet Mathieu functions approach.
... In our proposed schemes, double-sideband suppressed carrier (DSB-SC) and OSSB mm-wave carriers are generated with low-frequency local oscillator (LO) signals of 14.5 GHz and 17.5 GHz respectively, which reduce the cost of the system greatly. Traditionally, OSSB modulation has a higher receiver sensitivity compared to DSB modulation due to the higher optical carrier-to-sideband ratio (OCSR) resulting from the large carrier component at the central optical frequency [11]. However, we have demonstrated that lower receiver sensitivity can be obtained by using cascaded OSSB and optical carrier suppression (OCS) techniques compared with cascaded OCS and DSB modulation techniques. ...
We experimentally compared 60 GHz RoF fronthaul links employing DSB-SC and OSSB. OSSB link offers better receiver sensitivity (-5 dBm) for 8-Gbps 16-QAM signal at BER=2.3e-3, while DSB-SC link has a lower receiver sensitivity (2.6 dBm) requiring lower frequency LO and smaller bandwidth MZMs.
... However, the broadband light source (BLS) used for SAC encoding is not suitable for generating the optical millimeter, which is required by most wavelength reuse schemes. A coherent light source, generally a laser, is used to generate optical millimeters for up-and downlink transmissions by modulation schemes such as a double side band (DSB) [9] or a single side band (SSB) [10]. Unlike a laser with a near impulse spectrum, the broadband light source (BLS) for SAC encoding occupies a range of wavelength band of 1 to 10 THz. ...
... In this section, numerical analysis according to Equation (10) and simulations done by Optisystem TM are both demonstrated. Received user power P is defined as P sr = P 1 = P 2 /2, and user numbers are K 1 = K 2 = 3. ...
A new scheme of radio-over-fiber (RoF) network based on spectral-amplitude-coding (SAC) optical code division multiple access (OCDMA) is herein proposed. Differential service is provided by a power control scheme that classifies users into several classes and assigns each of them with a specific power level. Additionally, the wavelength reuse technique is adapted to support bidirectional transmission and reduce base station (BS) cost. Both simulation and numerical results show that significantly differential quality-of-service (QoS) in bit-error rate (BER) is achieved in both downlink and uplink transmissions.
... Among them, using an external intensity modulator to generate optical mm-waves is the simplest and the most accurate, and shows great potential for the high-frequency optical mm-wave generation. Different modulation schemes include optical single-sideband (OSSB) modulation (Attygalle et al. 2005;Gao et al. 2013;Li et al. 2013Li et al. , 2015, optical double-sideband (ODSB) modulation (Hung et al. 2013;Li et al. 2011;Montgomery and DeSalvo 1995), and optical carrier suppression (OCS; Jia et al. 2006;Lin et al. 2008;Yu and Chang 2004). ...
In this work, the time shift of code edges, due to the fiber chromatic dispersion in conventional optical single-sideband modulation, is investigated by theory and simulations. The influence that transmission pulse type of the data signal has on the system performance is discussed emphatically. It is found that, within half limited distance of the system, return-to-zero pulse is suitable for short distance (<10 km) transmission, whereas none-return-to-zero pulse is more suitable for long-haul high-quality and stable signal transmission. To solve the problem of time shift of code edges, an improved scheme is proposed, which only modulates data on the optical carrier. Compared with the original scheme, the time shift of code edges is eliminated. Besides, the performance of the system can be upgraded greatly.
