Nonlinearity compensation using optical phase conjugation deployed in discretely amplified transmission systems

We introduce a closed form equation, validated by simulations and experimental results, that predicts the residual nonlinear noise ratio in mid-link OPC assisted discretely amplified systems. The model anticipates the reduction in performance enhancement achieved by mid-link OPC as the bandwidth of the modulated signals increases. The numerical analysis shows that uncompensated signal-signal interactions limit the performance improvement achieved by the introduction of additional OPCs. The numerical analysis predicts that the deployment of shorter amplifier spacing will lead to a greater performance enhancement. The numerical results are validated by experimentally testing of 2x, 4x, and 8x28Gbaud PM-QPSK systems with mid-link OPC compensation in a discretely amplified system with 100km amplifier spacing. The experimentally obtained reach enhancement (43%, 32%, and 24% for 2x28Gbaud, 4x28Gbaud, and 8x28Gbaud, respectively) confirms that the compensation efficiency of mid-link OPC is highly dependent on the number of channels (bandwidth) propagating along the system

Optimization of parametric comb generation using interferometric wavelength selective switch

Poster: We propose and demonstrate frequency comb regeneration using parametric mixer dispersion managed by interferometric wavelength selective switch. The results show a good control over the bandwidth/flatness of the comb generated by the parametric process

Maxillary and mandibular dental arch forms in a Jordanian population with normal occlusion

Background: Ethnic background has been claimed to affect arch form. The purpose of this study was to describe and elucidate the maxillary and mandibular arch forms in Jordanian population and to develop a classification method for these forms which could be employed to construct orthodontic archwires accordingly. Methods: The sample was comprised of study casts of five hundred and twenty subjects (231 males and 289 females with a mean age of 15.4 ± 1.02 years). All subjects had permanent dentition with normal occlusion. A mathematical method associated with a polynomial function of 6th degree was employed to assess the dental arch forms. The resultant arch forms were classified into 5 groups for both the maxilla and mandible utilizing a computer software with special code designed for this study. Each group was subdivided into 3 subgroup sizes namely: small, medium, and large. Results: Catenary arch form was found in 47% and 41.2% (p ˂ 0.01) of maxilla and mandible arch forms, respectively. Form 2 (which is halfway between ellipse and U-shaped arch form) was found in 27.7% and 26.7%. Medium size arch form was found in 55.4% of the maxillary and 65.6% of the mandibular arch forms. Conclusion: Catenary arch form was the most prevalent arch form, followed by wide elliptical form. The other forms, which included tudor arch, tapered equilateral and quadrangular forms were less frequent. Regarding size, the medium size was the most prevalent among the studied samples.This study was bankrolled through a grant from the Deanship of Scientific Research/ Jordan University of Science and Technology (Grant No. 20090030). The Deanship of Scientific Research had absolutely no role in the design, collection, analysis, and interpretation of data and writing of the manuscript of this study

Experimental demonstration of 72% reach enhancement of 3.6Tbps optical transmission system using mid-link Optical Phase Conjugation

We experimentally demonstrate nonlinear noise compensation in optical phase conjugation assisted 1st order Raman amplified 30x30Gbaud DP-QPSK transmission system with a spectral efficiency of 3.6b/s/Hz. We show that by optimizing the link symmetry, even with only 1st order Raman amplification a single, mid-link, optical phase conjugation compensates for 90% off the signal-signal nonlinear interference resulting in a 2.3dB performance enhancement. We show that increasing the number of optical phase conjugation s in the presence of 10% residual nonlinearity results in a reduction in the performance enhancement owing to an enhancement in the nonlinear noise generation efficiency of the system. We achieve a record 72% optical phase conjugation enabled reach enhancement of the 30x30Gbaud DP-QPSK signals

Demonstration of phase-conjugated subcarrier coding for fiber nonlinearity compensation in CO-OFDM transmission

In this paper, we demonstrate through computer simulation and experiment a novel subcarrier coding scheme combined with pre-electrical dispersion compensation (pre-EDC) for fiber nonlinearity mitigation in coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. As the frequency spacing in CO-OFDM systems is usually small (tens of MHz), neighbouring subcarriers tend to experience correlated nonlinear distortions after propagation over a fiber link. As a consequence, nonlinearity mitigation can be achieved by encoding and processing neighbouring OFDM subcarriers simultaneously. Herein, we propose to adopt the concept of dual phase conjugated twin wave for CO-OFDM transmission. Simulation and experimental results show that this simple technique combined with 50% pre-EDC can effectively offer up to 1.5 and 0.8 dB performance gains in CO-OFDM systems with BPSK and QPSK modulation formats, respectively

4 Tb/s transmission reach enhancement using 10 × 400 Gb/s super-channels and polarization insensitive dual band optical phase conjugation

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