Showing papers on "Polarization mode dispersion published in 2016"
TL;DR: In this article, a pseudo-high-order GVLVS with a two-humped pulse along one polarization and a single-hump pulse along the orthogonal polarization was obtained.
Abstract: Manipulation of group-velocity-locked vector solitons (GVLVSs) is numerically proposed and experimentally demonstrated. A pseudo-high-order GVLVS could be generated from a fundamental GVLVS with the help of a polarization-resolved system. Specifically, a pseudo-high-order GVLVS with a two-humped pulse along one polarization and a single-humped pulse along the orthogonal polarization could be obtained. The phase difference between the two humps could be 180°.
198 citations
TL;DR: A thorough survey of third-generation FEC codes, suitable for 100 G and beyond optical networks, is presented and a qualitative categorization and comparison of the proposed schemes based on their main features, such as net coding gain and BER are provided.
Abstract: Due to the rapid increase in network traffic in the last few years, many telecommunication operators have started transitions to 100-Gb/s optical networks and beyond. However, high-speed optical networks need more efficient forward error correction (FEC) codes to deal with optical impairments, such as uncompensated chromatic dispersion, polarization mode dispersion, and nonlinear effects, and keep the bit error rate (BER) at long distances sufficiently low. To address these issues, new FEC codes, called third-generation codes, have been proposed. A majority of these codes are based on soft-decision decoders and can provide higher coding gain as compared with their predecessors. This paper presents a thorough survey of third-generation FEC codes, suitable for 100 G and beyond optical networks. Furthermore, this paper discusses the main advantages and drawbacks of each scheme and provides a qualitative categorization and comparison of the proposed schemes based on their main features, such as net coding gain and BER. Information about the complexity of each scheme is given as well.
134 citations
TL;DR: A compact silicon polarization beam splitter based on grating-assisted contradirectional couplers (GACCs) that exhibits tolerance in width variation, and the polarization extinction ratios remain higher than 20 dB for both polarizations when the width variation is adjusted from + 10 to -10 nm.
Abstract: We demonstrate a compact silicon polarization beam splitter (PBS) based on grating-assisted contradirectional couplers (GACCs). Over 30-dB extinction ratios and less than 1-dB insertion losses are achieved for both polarizations. The proposed PBS exhibits tolerance in width variation, and the polarization extinction ratios remain higher than 20 dB for both polarizations when the width variation is adjusted from + 10 to –10 nm. Benefiting from the enhanced coupling by the GACCs, the polarization extinction ratio can be kept higher than 15 dB and the insertion loss is lower than 2 dB for both polarizations when the coupling length varies from 30.96 to 13.76 μm.
112 citations
TL;DR: In this paper, the authors experimentally demonstrate the benefit of polarization insensitive dual-band optical phase conjugation for up to ten 400 GB/s optical super-channels using a Raman amplified transmission link with a realistic span length of 75 km.
Abstract: In this paper, we experimentally demonstrate the benefit of polarization insensitive dual-band optical phase conjugation for up to ten 400 Gb/s optical super-channels using a Raman amplified transmission link with a realistic span length of 75 km. We demonstrate that the resultant increase in transmission distance may be predicted analytically if the detrimental impacts of power asymmetry and polarization mode dispersion are taken into account.
102 citations
TL;DR: In this paper, the authors introduce design and fabrication techniques that allow analogous dispersion control in chip-integrated optical microresonators, and thereby demonstrate higher-order, wide-bandwidth dispersion over an octave of spectrum.
Abstract: The control of dispersion in fibre optical waveguides is of critical importance to optical fibre communications systems and more recently for continuum generation from the ultraviolet to the mid-infrared. The wavelength at which the group velocity dispersion crosses zero can be set by varying the fibre core diameter or index step. Moreover, sophisticated methods to manipulate higher-order dispersion so as to shape and even flatten the dispersion over wide bandwidths are possible using multi-cladding fibres. Here we introduce design and fabrication techniques that allow analogous dispersion control in chip-integrated optical microresonators, and thereby demonstrate higher-order, wide-bandwidth dispersion control over an octave of spectrum. Importantly, the fabrication method we employ for dispersion control simultaneously permits optical Q factors above 100 million, which is critical for the efficient operation of nonlinear optical oscillators. Dispersion control in high-Q systems has become of great importance in recent years with increased interest in chip-integrable optical frequency combs.
98 citations
TL;DR: It is found that this fiber has mode coupling properties analogous to elliptical core PM fibers, which yield ~10 × or more lower crosstalk than for conventional LP fiber mode orders with the same Δneff, which confirms that, for OAM modes, birefringent perturbation rather than shape perturbations matter most.
Abstract: Enabled by an enhanced effective index separation (Δneff = 1.7 × 10-4) and low transmission loss (0.8dB/km), OAM states are propagated over 13.4km in an air core fiber using a recirculating fiber loop. We observe that intermodal crosstalk decreases rapidly with increasing effective index separation, Δneff, and an order of magnitude lower crosstalk may be achieved just by doubling Δneff. We find that, in agreement with coupled power theory, our fiber has mode coupling properties analogous to elliptical core PM fibers, which yield ~10 × or more lower crosstalk than for conventional LP fiber mode orders with the same Δneff. This confirms that, for OAM modes, birefringent perturbations rather than shape perturbations matter most. In the process of performing the loop experiment, we demonstrate that OAM states in these fibers can be preserved with low loss (≤ 0.2dB) and low crosstalk (-15dB) while splicing distinct segments of the air-core fiber. For well-designed fibers, we demonstrate that OAM modes can travel distances relevant for large-scale data centers.
62 citations
TL;DR: In this paper, a cascade-based nonlinear equalization (VNLE) structure for multistep fiber nonlinearity compensation is proposed, in which the dispersion compensation is performed either before (cascade-1) or after (Cascade-2) the compensation in each step.
Abstract: Toward reduced-complexity digital implementation, frequency domain Volterra-based nonlinear equalization (VNLE) structures for multistep fiber nonlinearity compensation are proposed. In the cascade structures, nonlinear equalization is performed before (cascade-1) or after (cascade-2) the dispersion compensation in each step. Superior performance with the shorter discrete Fourier transform (DFT) lengths and fewer equalization steps compared to the conventional VNLE with parallel structure is demonstrated in a transmission experiment. The experimental results are obtained for 256 Gb/s single-carrier dual-polarization 16-ary quadrature-amplitude-modulation with root-raised-cosine pulse shaping and a roll-off factor of 0.1. The new cascade structures demonstrate superior robustness to insufficient DFT lengths and/or a limited complexity budget. Compared to the conventional parallel arrangement of linear and nonlinear compensation filters, the cascade-1 structure provides more than 90% complexity reduction without any notable performance penalty. The structure enables the extension of the transmission reach by 1570 km, a 48% increase compared to the linear solution that uses only electronic dispersion compensation.
52 citations
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20 Mar 2016
TL;DR: With the recent conclusion of the NG-PON2 standards in the ITU-T, the fiber access industry is now considering where to go next in the evolution of passive optical networks.
Abstract: With the recent conclusion of the NG-PON2 standards in the ITU-T, the fiber access industry is now considering where to go next. This paper reviews some of the options for the evolution of passive optical networks.
45 citations
TL;DR: In this paper, the authors proposed the time-domain least square (TDLS) channel estimation method for coherent optical OFDM/OQAM (CO-OFDM) systems.
Abstract: Suppressing the intrinsic imaginary interference (IMI) effect induced by the multiple-path fading channel is the key technology for maintaining the good performance of the orthogonal frequency-division multiplexing offset-quadrature amplitude modulation (OFDM/OQAM) systems. Recently, the first theoretical discussion on the IMI effect and the corresponding frequency-domain channel estimation method for polarization-division-multiplexed (PDM) coherent optical OFDM/OQAM (CO-OFDM/OQAM) system has been studied. The full-loaded and the half-loaded channel estimation methods have been proposed to mitigate the IMI effect. However, for these frequency-domain methods, the condition that the symbol interval is much longer than the maximum channel delay spread has to be satisfied. When the transmission distance is long, the frequency-domain residual errors induced by the chromatic dispersion (CD) and polarization mode dispersion (PMD) reduce the channel estimation accuracy evidently. In this paper, we systematically discuss the time-domain channel transmission model for PDM CO-OFDM/OQAM systems. With the analysis of the distribution of the received additive noise, we propose the time-domain least square (TDLS) channel estimation method for PDM CO-OFDM/OQAM systems. Compared with the frequency-domain methods, the TDLS method promotes the system robustness against both the IMI effect and the additive noise significantly. The computational complexities and the transmission performance have been compared for both the TDLS and the frequency-domain full-loaded methods. The theoretical analysis is validated by numerical Monte Carlo simulations of the PDM CO-OFDM/OQAM system.
45 citations
TL;DR: In this paper, the authors proposed a blind polarization demultiplexing using the signal distribution in Stokes space, which significantly simplified the DSP procedures by using a single-stage blind 3 × 2 real-value multiple-input multiple-output equalization.
Abstract: The conventional intensity modulation with direct detection faces the capacity bottleneck beyond 100-Gb/s per wavelength, due to its 1-dimension (1-D) modulation and detection. To increase the spectral efficiency, there emerge a variety of direct detection subsystems based on the Stokes vector receiver (SV-R). The Stokes space contains the intensity information of three independent polarizations. Therefore, the SV-R enlarges the detection dimensions at receiver to 3. The SV-R can recover any 2-D or 3-D signal modulated in Stokes space. One of the most significant features of SV-R is the DSP-enabled polarization demultiplexing. Instead of a 2 × 2 Jones matrix, in Stokes space, a 3 × 3 rotation matrix (RM) characterizes the polarization variation during fiber transmission. Previously, we have demonstrated a training-assisted polarization demultiplexing algorithm, which uses three basis vectors in Stokes space to estimate the RM. In this paper, we propose a blind polarization demultiplexing using the signal distribution in Stokes space. Combined with the blind adaptive algorithm, the new method converts the two-stage polarization demultiplexing (RM estimation and channel equalization) to a single-stage blind 3 × 2 real-value multiple-input multiple-output equalization, which significantly simplify the DSP procedures. We experimentally demonstrate the SV-R based on either training or blind demultiplexing algorithms, and compare the performance between them.
42 citations
TL;DR: It is shown that the dissipative solitons resonance in an ytterbium-doped fiber ring laser in which all the elements are polarization maintaining (PM) can be tuned to multiple right-angle trapezoid-shaped pulses, per round-trip.
Abstract: We investigated the dissipative solitons resonance in an ytterbium-doped fiber ring laser in which all the elements are polarization maintaining (PM). A semiconductor saturable absorber mirror was used as a mode-locker. The cavity included a normal dispersion single-mode fiber (SMF) and an anomalous dispersion photonic crystal fiber. The change of the length of the PM SMF allows the variation of the net-normal dispersion of the cavity in the range from 0.022 ps2 to 0.262 ps2. As the absolute value of the net-normal dispersion increases from 0.022 ps2 to 0.21 ps2, a square-shaped single pulse transformed to a single right-angle trapezoid-shaped pulse, and, at the dispersion of 0.262 ps2, to multiple right-angle trapezoid-shaped pulses, per round-trip.
TL;DR: A trench-assisted heterogeneous multicore fiber optimized in terms of higher-order dispersion and crosstalk for radiofrequency true time delay operation is reported, opening the way towards the development of compact fiber-integrated solutions that enable the implementation of a variety of distributed signal processing functionalities that will be key in future fiber-wireless communications networks and systems.
Abstract: We report a trench-assisted heterogeneous multicore fiber optimized in terms of higher-order dispersion and crosstalk for radiofrequency true time delay operation. The analysis of the influence of the core refractive index profile on the dispersion slope and effective index reveals a tradeoff between the behavior of the crosstalk against fiber curvatures and the linearity of the propagation group delay. We investigate the optimization of the multicore fiber in the framework of this tradeoff and present a design that features a group delay relative error below 5% for an optical wavelength range up to 100 nm and a crosstalk level below -80 dB for bending radii larger than 103 mm. The performance of the true time delay line is validated in the context of microwave signal filtering and optical beamforming for phased array antennas. This work opens the way towards the development of compact fiber-integrated solutions that enable the implementation of a variety of distributed signal processing functionalities that will be key in future fiber-wireless communications networks and systems.
TL;DR: In this work, detection and alignment of DP-QAM transmitter IQ and XY skews using reconfigurable interference is experimentally demonstrated and fast detection algorithm for arbitrary skew is proposed and experimentally verified.
Abstract: Dual-polarization quadrature amplitude modulation (DP-QAM) is one of the feasible paths towards 100-Gb/s, 400-Gb/s and 1-Tb/s optical fiber communications systems. For DP-QAM transmitter, the time mismatch between the in-phase and quadrature (IQ) or x-polarized and y-polarized (XY) tributary channels is known as the IQ or XY skew. Large uncompensated IQ or XY skew can significantly degrade the optical fiber communications system performance. Sometimes, time-interleaved return-to-zero (RZ) DP signal is preferred with lower nonlinear polarization scattering induced penalty. In this work, detection and alignment of DP-QAM transmitter IQ and XY skews using reconfigurable interference is experimentally demonstrated. For IQ skew detection, a total dynamic range of 26.4 dB is achieved with ~1-dB power change for 0.5-ps skew from well alignment. For XY skew detection, it shows 23.2-dB dynamic range, and ~1.5-dB power change is achieved for 1-ps XY skew. Fast detection algorithm for arbitrary skew is also proposed and experimentally verified. The scheme is compatible with different modulation formats, flexible data sequences, and variable waveforms.
TL;DR: In this article, a fixed-analyzer technique is proposed and demonstrated to characterize the phenomenon of random cross coupling in OAM fibers, and two different types of OAM fiber are examined.
Abstract: The orbital-angular-momentum (OAM) modes in optical fibers have polarization mode dispersion (PMD) properties similar to those of single-mode fibers (SMFs). The + l and − l order OAM modes supported by the same fiber vector modes undergo random cross coupling and exhibit a frequency-dependent time delay. We name this effect “OAM-PMD” and extend the formalism developed for PMD in SMFs to describe OAM-PMD. The characteristics of the modal beat lengths, birefringence correlation lengths, and the mean value of OAM-PMD are investigated. A fixed-analyzer technique is proposed and demonstrated to characterize this phenomenon in OAM fibers. Two different types of OAM fiber are examined. The measured results are compared with the theoretical calculations.
TL;DR: In this paper, a singlemode octagonal photonic crystal fiber (OPCF) is proposed to simultaneously achieve high birefringence and ultra-flattened ultra-high negative dispersion.
Abstract: A single-mode octagonal photonic crystal fiber (OPCF) is proposed to simultaneously achieve high birefringence and ultra-flattened ultra-high negative dispersion. Simulation results demonstrate that by introducing an elliptical air hole in the center of the core, it is possible to obtain a large average dispersion of −608.93 ps/nm/km with an absolute dispersion variation of −12.7 ps/nm/km over 1.46–1.625 $\mu \text{m}$ wavelength bands for fundamental slow-axis mode. Besides, with optimal design parameters, a high birefringence of $1.81\times 10^{\mathrm {-2}}$ and a very low confinement loss of 0.04 dB/km are achieved at 1.55 $\mu \text{m}$ . The proposed OPCF can be used in cost-effective residual dispersion compensation and optical sensors.
TL;DR: It is shown that reducing the spacing between phase conjugations allows for significantly improved performance in the presence of polarisation mode dispersion or a significant relaxation in the acceptable level of polarizationmode dispersion.
Abstract: In this paper, we numerically investigate the impact of polarisation mode dispersion on the efficiency of compensation of nonlinear transmission penalties for systems employing one of more inline phase conjugation devices. We will show that reducing the spacing between phase conjugations allows for significantly improved performance in the presence polarisation mode dispersion or a significant relaxation in the acceptable level of polarization mode dispersion. We show that these results are consistent with previously presented full statistical analysis of nonlinear transmission appropriately adjusted for the reduced section length undergoing compensation.
TL;DR: In this paper, the authors compared two models of the highly birefringent photonic crystal fiber using a full vectorial finite element method with anisotropic perfectly matched boundary layers.
01 Aug 2016
TL;DR: In this article, a new proposed method of electronic dispersion compensation in the transmission of microwave signals through fiber-optic lines was proposed, and the results of experimental studies of this method were presented.
Abstract: Methods of dispersion compensation in fiber-optic communication lines. A new proposed method of electronic dispersion compensation in the transmission of microwave signals through fiber-optic lines. Represents is proposed the results of experimental studies of this method.
TL;DR: A joint multi-polarization-effect tracking and equalization method based on two extended Kalman filters, which can cope with state of polarization (SOP) tracing, polarization demultiplexing, equalization for polarization dependent loss (PDL) and polarization mode dispersion (PMD) in PDM-M-QAM coherent optical communication system is proposed.
Abstract: We propose a joint multi-polarization-effect tracking and equalization method based on two extended Kalman filters, which can cope with state of polarization (SOP) tracing, polarization demultiplexing, equalization for polarization dependent loss (PDL) and polarization mode dispersion (PMD) in PDM-M-QAM coherent optical communication system. The mathematical model of the proposed method is given and analyzed in detail. Through simulation, the proposed method is proved to be very effective in a 28 Gbaud/s PDM-16QAM system. With the proposed method, SOP tracing speed is up to 110 Mrad/s for azimuth angle and 1200 krad/s for phase angle, respectively, and PDL and PMD can be equalized simultaneously in the values of 10 dB and more than half of the symbol period.
TL;DR: In this article, a depolarizer based on a collection of half-wave plates with randomly distributed optic axes is proposed, which is demonstrated by means of dynamically photopatterning liquid crystal into randomly aligned homogeneous domains.
Abstract: We propose a depolarizer based on the principle of a collection of half-wave plates with randomly distributed optic axes. The design is demonstrated by means of dynamically photopatterning liquid crystal into randomly aligned homogeneous domains. We characterize the liquid crystal depolarizer for 1550 nm and C-band (1520–1610 nm). A degree of polarization of less than 5% is obtained for any linearly polarized light. This study provides a practical candidate for high-performance depolarizers.
TL;DR: A training-based channel estimation algorithm is proposed for the faster-than-Nyquist polarization division multiplexed m-ary quadrature amplitude modulation systems with Tomlinson-Harashima precoding (THP), robust to the convergence failure phenomenon suffered by the existing algorithm, yet remaining format-transparent.
Abstract: A training-based channel estimation algorithm is proposed for the faster-than-Nyquist polarization division multiplexed m-ary quadrature amplitude modulation (m = 4, 16, 64) systems with Tomlinson-Harashima precoding (THP). This is robust to the convergence failure phenomenon suffered by the existing algorithm, yet remaining format-transparent. Simulation results show that the proposed algorithm requires a reduced optical signal-to-noise ratio to achieve a certain bit error rate in the presence of first-order polarization mode dispersion and phase noise introduced by the laser linewidth.
TL;DR: A novel fiber structure having an air-hole at the center is proposed for reducing the group delay spread of strongly coupled 3-core fibers, leading to strong modal mixing in the fiber, and hence, small GDS.
Abstract: The effect of bending and twisting on the group delay spread (GDS) of strongly coupled 3-core fibers is investigated. For the random perturbation inducing modal coupling in the fiber, two physical mechanisms, microbending or macrobending with random twist, are considered. Calculated results show that both mechanisms lead to the same effect, namely, reduced GDS under strong coupling regime. Furthermore, a novel fiber structure having an air-hole at the center is proposed for reducing the GDS. By placing the air-hole, the effective index difference between fundamental and the higher order modes is reduced, leading to strong modal mixing in the fiber, and hence, small GDS. Calculated GDS of the fiber with air-hole is almost 1/5 compared with that of the fiber without air-hole.
TL;DR: Thanks to the innovative modification of frequency-shift operation, the MIMO equalization enables synchronous output of dual-carrier signals with robust performance against frequency offset, laser phase noise, as well as polarization mode dispersion (PMD), the experimental back-to-back transmission of PDM-16QAM signal has 8.3-dB OSNR improvement using the proposed MIMo processing.
Abstract: We propose an intercarrier interference (ICI) mitigation scheme for dual-carrier superchannel transmission. Using the modified decision directed least mean square (DD-LMS) based multi-input multi-output (MIMO) processing, we can simultaneously realize both polarization division demultiplexing and ICI mitigation for PDM-m-PSK and PDM-m-QAM formats. Thanks to the innovative modification of frequency-shift operation, the MIMO equalization enables synchronous output of dual-carrier signals with robust performance against frequency offset, laser phase noise, as well as polarization mode dispersion (PMD). The experimental back-to-back transmission of PDM-16QAM signal has 8.3-dB OSNR improvement using the proposed MIMO processing. Three dual-carrier 160-Gb/s PDM-16QAM superchannels within 25-GHz grid are experimentally transmitted over 640-km standard single-mode fiber (SSMF), leading to net spectral efficiency of 5.7b/s/Hz.
TL;DR: A non-intrusive OSNR measurement technique relying on the detailed spectral comparison of an optical signal with its "noise-free" spectrum is described, including mathematical basis, validity conditions and algorithmic steps.
Abstract: A non-intrusive OSNR measurement technique relying on the detailed spectral comparison of an optical signal with its "noise-free" spectrum is described, including mathematical basis, validity conditions and algorithmic steps. The technique's performance is experimentally demonstrated with 100G PM-QPSK and 200G PM-16QAM signals subject to fiber non-linearity induced by 100G PM-QPSK and 10G NRZ-OOK neighbors. The OSNR measurement performance is also demonstrated when root-raised cosine spectral shaping is applied to the signals, with channel spacings of 50GHz and 37.5GHz. Experimental results for OSNR levels up to 30dB and launch powers up to 3dB above the optimum BER launch conditions are shown for different system and signal configurations.
10 Jul 2016
TL;DR: In this article, the authors investigate the impact of local fiber birefringence on nonlinear compensation techniques in non-dispersion managed transmission links and describe the beneficial mechanism of a low-complex modification of the well-known digital back propagation (DBP) technique, which is based on single measurements of accumulated differential group delay and principal states of polarization (PSP) at the receiver.
Abstract: In this paper, we investigate the impact of the stochastic nature of local fiber birefringence on nonlinear compensation techniques in non-dispersion managed transmission links. We describe the beneficial mechanism of a low-complex modification of the well-known digital back propagation (DBP) technique, which is based on single measurements of accumulated differential group delay (DGD) and principal states of polarization (PSP) at the receiver. Furthermore, we discuss limits of the DBP capability to increase spectral efficiency and reach distance, and compare exemplary application cases.
TL;DR: An analytical model for the stable RF transfer system based on passive phase correction is established, and the techniques developed in the last few years in solving the problems of the method are described.
Abstract: The transfer of radio frequency (RF) signal via optical fiber is widely adopted in distributed antenna systems and clock standard disseminating networks. To suppress the phase variation caused by fiber length fluctuation, passive phase correction technique based on frequency mixing has been proved as a promising approach due to its significant advantages over the traditional active compensation technique in terms of complexity, compensation speed, and compensation range. The phase correction can be done either in the transmitter or in the receiver, but it usually requires many stages of electronic mixing and auxiliary microwave signals, which not only increases the cost of the link but also degrades the quality of the transmitted signal. In addition, the effect of chromatic dispersion, polarization mode dispersion, and coherent Rayleigh noise in the optical fiber will further deteriorate the phase noise of the signal after transmission. In this paper, an analytical model for the stable RF transfer system based on passive phase correction is established, and the techniques developed in the last few years in solving the problems of the method are described. Future prospects and perspectives are also discussed.
TL;DR: In this paper, the group-delay dispersion of an optical fiber was measured with the time-of-flight method, using fingerprint-like characteristic spectra from a mode-locked fiber laser source.
Abstract: The group-delay dispersion of an optical fiber was measured with the time-of-flight method, using fingerprint-like characteristic spectra from a mode-locked fiber laser source. To determine the group-delay dispersion up to the fourth order, least-squares fitting was applied to the overall time waveform mapped on the time axis for the fingerprint-spectral broadband pulses through a long optical fiber. The analysis of all 4003 data points reduced statistical uncertainty, and provided second-, third-, and fourth-order dispersion with uncertainties of 0.02%, 0.4%, and 4%, respectively.
TL;DR: In this article, the intramodal dispersion within groups of quasi-degenerate modes in step-index few-mode fibers is studied with a semianalytic approach.
Abstract: The intramodal dispersion within groups of quasi-degenerate modes in step-index few-mode fibers is studied with a semianalytic approach. By means of theoretical analyses based on accurate modeling of mode coupling, the most general problem of arbitrary high-order modes is simplified to five different cases, which are analyzed numerically. Results show that the spin may reduce intramodal dispersion if its rate is tuned finely, similarly to single-mode fibers. At variance with this case, however, spin may also increase the intramodal dispersion of high-order modes for particular conditions. Being limited to intramodal dispersion, the analysis reported here does not consider the modal dispersion accumulated between different groups of nondegenerate modes. Nonetheless, results find application in the so-called low mode coupling regime.
TL;DR: The proposed technique is based on the co-propagation of an arbitrary shaped signal together with an orthogonally polarized intense fast sinusoidal beating within a normally dispersive optical fiber to design an all-optical magnification and sampling function free from any active gain medium or additional amplified spontaneous noise emission.
Abstract: We theoretically and experimentally investigate the design of an all-optical magnification and sampling function free from any active gain medium or additional amplified spontaneous noise emission. The proposed technique is based on the co-propagation of an arbitrary shaped signal together with an orthogonally polarized intense fast sinusoidal beating within a normally dispersive optical fiber. This process allows us to experimentally demonstrate a 40-GHz sampling operation as well as an 8-dB magnification of an arbitrary shaped nanosecond signal around 1550 nm in a 5-km long optical fiber. The experimental observations are in good agreement with numerical and theoretical analysis.
TL;DR: In this article, the guiding properties of a new type of photonic crystal fibers where air-holes are arranged in a circular pattern (C-PCF) with a silica matrix have been investigated.
Abstract: The guiding properties of a new type of photonic crystal fibers where air-holes are arranged in a circular pattern (C-PCF) with a silica matrix have been investigated. The dispersion properties of the fiber with different spacing of circle and air-hole diameter have been studied in detail. It is shown that C-PCFs with smaller values of radius and higher air-filling fraction can be used as dispersion compensating fiber. A comparison between fibers with circular and triangular lattice has also been performed, taking into account the dispersion properties and the effective area in the wavelength range between 1200 nm and 1600 nm. C-PCF can better compensate the inline dispersion for both single wavelength and broadband wavelength applications which is a unique property not observed by regular triangular-lattice or square-lattice PCFs. The fiber provides higher effective area, making it a better candidate for high power accumulations in the core of the fiber. The fiber also shows red-shifting of the first zero dispersion wavelength (ZDW), flatter dispersion slope and lower Group Velocity Dispersion (GVD) in the normal dispersion region thereby making it a better candidate for high power nonlinear applications like super-continuum generation, soliton pulse propagation etc . With the above advantages, we have considered a series study of these circular-lattice structures for various geometrical parameters and temporal pulses in order to explore the characteristics of broadband supercontinuum generation. This design study for high power supercontinuum generation will be very helpful for potential application of new sources in various fields like astronomy, climatology, spectroscopy optical tomography and sensing etc . to name a few.