• Journal of Advanced Navigation Technology
• /
• v.18 no.2
• /
• pp.158-164
• /
• 2014

For transmitting the ultra-high speed optical signals with better performance, the techniques to suppress or mitigate the signal distortion due to group velocity dispersion and optical Kerr effects are required. Dispersion management (DM), optical phase conjugation, and the combination of these two are promising techniques to compensate for the signal distortion. However, the fixed length of single mode fiber (SMF) and the fixed residual dispersion per span (RDPS) usually used in these optical links restricts flexible link configuration. The goal of this paper is to investigate the possibility of the flexible configurations of the ultra-high and long-haul optical transmission systems by using the artificial and the random distribution of SMF length and RDPS of each fiber spans consisted of the optical link. It is confirmed that the proposed link configurations should be one of the methods suitable for implementing the flexible optical transmission systems, however which depend on other link parameters, such as the averaged RDPS, and the launch power.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.9
• /
• pp.2219-2226
• /
• 2013

Optical phase conjugation combining with dispersion management (DM) is promising technique to compensate for signal distortion due to group velocity dispersion (GVD) and nonlinear Kerr effects in optical communication systems. However the fixed residual dispersion per span (RDPS) usually used in the optical links with OPC and DM restricts the flexible link configuration. In this paper, OPC links combining DM of the randomly distributed RDPS is proposed for implementing the flexible optical transmission network. It is confirmed that the excellent compensation in the optical links with the randomly distributed RDPS is obtained, limiting the launch power of WDM channels to the relatively low. It is also confirmed that the relatively high launch power WDM channels are effectively transmitted through the optical links with the randomly distributed RDPS of averaged 50 - 100 ps/nm.

• Journal of information and communication convergence engineering
• /
• v.13 no.4
• /
• pp.228-234
• /
• 2015

The system performance improvement in dispersion managed (DM) links combined with optical phase conjugator (OPC) for compensating for optical signal distortion due to group velocity dispersion and nonlinear fiber effects has been reported. However, in DM link combined OPC, the equalities of the lengths of single-mode fibers (SMFs), the length of dispersion compensating fibers (DCFs), the dispersion coefficient of DCF, and the residual dispersion per span (RDPS) with respect to an OPC restrict a flexible link configuration. Thus, in this paper, we propose a flexible optical link configuration with inequalities of link parameters, the so-called "pseudo-symmetric configuration." Simulation results show that, in the restricted RDPS range of 450 ps/nm to 800 ps/nm, the improvement in the system performance of the proposed pseudo-symmetrically configured optical links is better than that of the asymmetrically configured optical links. Consequently, we confirmed that the proposed pseudo-symmetric configuration is effective and useful for implementing a reconfigurable long-haul wavelength-division multiplexing (WDM) network.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.14 no.4
• /
• pp.405-411
• /
• 1989

Performance evaluation of inexpensive LCTV to function as a two-dimensional spatial light modulator is performed. Correction of the phase distortion of the device is performed using the substrate of hologram plate and index matching oil. A new method for eliminating electrode grid pattern that incorporates phase conjugation in a BaTiO3 crystal is proposed and experimented.

• Journal of information and communication convergence engineering
• /
• v.17 no.4
• /
• pp.227-233
• /
• 2019

In long-haul optical communication system consisting of standard single-mode fiber spans and fiber amplifiers, such as the erbium-doped fiber amplifier, performance is deteriorated by signal distortion due to chromatic dispersion and nonlinearity of the fiber. A combination of dispersion management and optical phase conjugation is an effective technique to compensate for the distortion. In an optical link configured by this combination, a dispersion map mainly affects the compensation of the distorted optical signals. This paper proposes new dispersion maps configured by the decaying or expanding distribution of residual dispersion per span (RDPS) in a dispersion-managed link combined with a midway optical phase conjugator. The effect of the proposed dispersion maps on the compensation for distorted 24 channel × 40 Gbps wavelength-division multiplexed signals was assessed through numerical simulation. It was confirmed that all the proposed dispersion maps are most appropriate for the compensation and, furthermore, for the flexibility of link configuration than conventional links.

• Journal of information and communication convergence engineering
• /
• v.20 no.4
• /
• pp.235-241
• /
• 2022

A dispersion map was proposed to improve the compensation effect of a distorted WDM (wavelength division multiplexed) channel in a dispersion-managed link coupled with optical phase conjugation. The dispersion map is an origin-symmetric structure around the optical phase conjugator in the middle of the transmission path. In addition, the dispersion map has a form in which a constant dispersion accumulation pattern is repeated regularly. Through simulation, we confirmed that the application of the origin-symmetric dispersion map with a repetitively shaped configuration was more effective in compensating for the distorted WDM channel than in the dispersion-managed link with a conventional dispersion map. In addition, we confirmed that the compensation effect could be increased when the cumulative dispersion distribution of the origin-symmetric distribution map had a positive value in the first half section and a negative value in the second half section. Further, we observed that as the number of repeated dispersion accumulation patterns increased, the residual dispersion per span should also be increased.

• Journal of Advanced Navigation Technology
• /
• v.19 no.6
• /
• pp.595-600
• /
• 2015

The implementation possibility of the flexible optical network configuration using the non-midway optical phase conjugator (OPC) in the dispersion-managed (DM) optical link for wavelength division multiplexed (WDM) transmission is demonstrated in this paper. It is confirmed that the implementation possibility of flexible link configuration is more increased, as number of fiber spans is more bigger and the residual dispersion per span (RDPS) is more large. It is also confirmed that the non-midway OPC link, in which RDPS of the latter half transmission section (after OPC) is decided by the averaged RDPS of the former half transmission section (before OPC), has more advantage for the flexible network configuration.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.723-725
• /
• 2013

The compensation characteristics are investigated as a function of the position an optical phase conjugation (OPC) in the optical transmission links with a randomly distributed residual dispersion per span (RDPS). The simulation results show that the optimal net residual dispersion (NRD) is decided to be 10 ps/nm and -10 ps/nm by precompensation and postcompensation, respectively, which are independence of the OPC positions.

• Journal of the Optical Society of Korea
• /
• v.20 no.3
• /
• pp.358-362
• /
• 2016

We present a new scheme for optical encryption of a binary image. In our method, the original binary data page is first divided into two identical pages. In each data page, the “on” and “off” pixels are represented by two discrete phases that are 90° apart. The first page corresponds to the phase conjugation of the second page, and vice versa. In addition, the wavefront of the two data pages is changed simultaneously from planar to spherical, for better encryption. The wavefront modification is represented by an extra phase shift, which is a function of position on the wavefront. In this way the two separate pages are both encrypted, and therefore the pages cannot be distinguished in a CCD. If the first page is used as an encrypted data page, then the second page is used as the decryption key, and vice versa. The decryption can be done by simply combining the two encrypted data pages. It is shown in our experiment that encryption and decryption can be fully accomplished in the optical domain.

• Journal of Advanced Navigation Technology
• /
• v.24 no.5
• /
• pp.408-414
• /
• 2020

The method of overcoming the limitation of optical phase conjugator applied into optical long-haul link for transmitting high capacity wavelength division multiplexed (WDM) channels was investigated. The configuration of optical link was based on dispersion-managed link, in which dispersion compensating fiber inserted into each fiber span with single mode fiber, and optical phase conjugator was added into suitable location of link. The maximum number of fiber spans as a function of the launch power of WDM channels in optical link with optical phase conjugator placed at the proposed location was induced and compared for analyzing the compensation performance of the distorted WDM channels. It was confirmed that the more optical phase conjugator depart from the midway of total transmission length, the less the distorted WDM channels was compensated, however, it was also confirmed that the degradation of compensation can be overcome by the suitable value of residual dispersion per span and by the reasonable choice of fiber span controlling total dispersion accumulated in overall transmission link.