Effect of carrier reshaping and narrow MUX-DEMUX filtering in 0.8 bit/s/Hz WDM RZ-DPSK transmission

Effect of the carrier shape in the ultra high dense wavelength division multiplexing (WDM) return to zero differential phase shift keying (RZ-DPSK) transmission has been examined through numerical optimization of the pulse form, duty cycle and narrow multiplex/de-multiplex (MUX/DEMUX) filtering parameters. © 2007 Springer Science+Business Media, LLC.

Inscription of narrow bandwidth bragg gratings in polymer optical fibers

We report on the production and characterization of narrow bandwidth fiber Bragg gratings (FBGs) in two spectral regions using polymer optical fibers (POFs). Narrow bandwidth FBGs are increasingly important for POF transmission systems, WDM technology and sensing applications. Long FBGs with resonance wavelength around 850 nm and 1550 nm were fabricated in several types of polymer optical fibers. The 3 dB FBG bandwidth varies from 0.22 nm down to 0.045 nm considering a Bragg grating length of 10 mm and 25 mm, respectively. © 2013 SPIE.

Narrow bandwidth Bragg gratings imprinted in polymer optical fibers for different spectral windows

The production and characterization of narrow bandwidth fiber Bragg gratings (FBGs) in different spectral regions using polymer optical fibers (POFs) is reported. Narrow bandwidth FBGs are increasingly important for POF transmission systems, WDM technology and sensing applications. Long FBGs with resonance wavelength around 600-nm, 850-nm and 1550-nm in several types of polymer optical fibers were inscribed using a scanning technique with a short optical path. The technique allowed the inscription in relative short periods of time. The obtained 3-dB bandwidth varies from 0.22 down to 0.045 nm considering a Bragg grating length between 10 and 25-mm, respectively. © 2013 Elsevier B.V.

Optical regeneration using self-phase modulation and quasi-continuous filtering

We propose a scheme for 211 optical regeneration based on self-phase modulation in fiber and quasi-continuous filtering. Numerical simulations demonstrate the possibility of increasing the transmission reach from 3500 to more than 6000 km at 10 Gb/s using 100-km spans. Spectral broadening is shown to be small using this technique, indicating its suitability for wavelength-division-multiplexing regeneration.

Design of FBG-based ultra-narrow asymmetric filter for transmission with 0.8 bit/s/Hz spectral efficiency without polarisation multiplexing

We propose a novel approach to ultra-narrow optical filtering based on a specially designed slightly asymmetric filter, which can be fabricated using fibre Bragg gratings. A feasibility of 8×40 Gbit/s DWDM RZ transmission with 0.8 bit/s/Hz spectral efficiency (without polarisation multiplexing) over 1280 km of SMF/DCF link without FEC has been confirmed by numerical modelling. © 2004 Elsevier Inc. All rights reserved.

Optimal span length in high-speed transmission systems with hybrid Raman-erbium-doped fiber amplification

We show, using nonlinearity management, that the optimal performance in high-bit-rate dispersion-managed fiber systems with hybrid amplification is achieved for a specific amplifier spacing that is different from the asymptotically vanishing length corresponding to ideally distributed amplification [Opt. Lett. 15, 1064 (1990)]. In particular, we prove the existence of a nontrivial optimal span length for 40-Gbit/s wavelength-division transmission systems with Raman-erbium-doped fiber amplification. Optimal amplifier lengths are obtained for several dispersion maps based on commonly used transmission fibers. © 2005 Optical Society of America.

Simple design of FBG-based VSB filters for ultra-dense WDM transmission

A novel approach to ultra-narrow optical vestigial sideband (VSB) filtering based on a specially designed fibre Bragg grating (FBG) operating in transmission is proposed. This design can be easily implemented by writing FBG-based filters for each WDM channel before MUX. The specially designed filter profile allows to take full advantage of crosstalk suppression while minimising waveform distortion.

Nonlinear inverse synthesis and eigenvalue division multiplexing in optical fiber channels

We scrutinize the concept of integrable nonlinear communication channels, resurrecting and extending the idea of eigenvalue communications in a novel context of nonsoliton coherent optical communications. Using the integrable nonlinear Schrödinger equation as a channel model, we introduce a new approach - the nonlinear inverse synthesis method - for digital signal processing based on encoding the information directly onto the nonlinear signal spectrum. The latter evolves trivially and linearly along the transmission line, thus, providing an effective eigenvalue division multiplexing with no nonlinear channel cross talk. The general approach is illustrated with a coherent optical orthogonal frequency division multiplexing transmission format. We show how the strategy based upon the inverse scattering transform method can be geared for the creation of new efficient coding and modulation standards for the nonlinear channel. © Published by the American Physical Society.

Simultaneous multiple channel all-optical NRZ to CSRZ and RZ to CSRZ format conversion using an SOA-NOLM

The optical conversion bandwidth for an all-optical modulation format converter, based on a semiconductor laser amplifier in a nonlinear optical loop mirror (SOA-NOLM), is investigated. 4 Â 10 Gbit/s channels are all- optically converted between both non-return-to-zero (NRZ) and return-to-zero (RZ) format to carrier- suppressed return-to-zero (CSRZ). WDM transmission of the converted signals over a 194 km fibre span is then demonstrated. The receiver sensitivity for the converted four wavelengths is measured and compared after transmission.

Simultaneous multiple channel all-optical NRZ to CSRZ and RZ to CSRZ format conversion using an SOA-NOLM

The optical conversion bandwidth for an all-optical modulation format converter, based on a semiconductor laser amplifier in a nonlinear optical loop mirror (SOA-NOLM), is investigated. 4 Â 10 Gbit/s channels are all- optically converted between both non-return-to-zero (NRZ) and return-to-zero (RZ) format to carrier- suppressed return-to-zero (CSRZ). WDM transmission of the converted signals over a 194 km fibre span is then demonstrated. The receiver sensitivity for the converted four wavelengths is measured and compared after transmission.

Simultaneous multiple channel all-optical NRZ to CSRZ and RZ to CSRZ format conversion using an SOA-NOLM

The optical conversion bandwidth for an all-optical modulation format converter, based on a semiconductor laser amplifier in a nonlinear optical loop mirror (SOA-NOLM), is investigated. 4×10 Gbit/s channels are all-optically converted between both non-return-to-zero (NRZ) and return-to-zero (RZ) format to carrier-suppressed return-to-zero (CSRZ). WDM transmission of the converted signals over a 194 km fibre span is then demonstrated. The receiver sensitivity for the converted four wavelengths is measured and compared after transmission. © 2014 Elsevier B.V. All rights reserved.

Optical 2R regeneration at 40 Gbit/s using saturable absorber in long-haul dispersion-managed fiber links

The optical regeneration is an attractive method to improve the performance of long-distance data transmission, though its application in high-speed fiber systems requires careful design consideration/optimization. In this letter we investigate 40 Gbit/s dispersion-managed fiber transmission with optical 2R regeneration based on quantum well saturable absorber and highly non-linear fiber. We demonstrate through numerical modeling a feasibility of a single channel transmission over 10,000 km using optimized system design. © 2003 Elsevier B.V. All rights reserved.

10 Mb/s visible light transmission system using a polymer light-emitting diode with orthogonal frequency division multiplexing

We present a newly designed polymer light-emitting diode with a bandwidth of ∼350 kHz for high-speed visible light communications. Using this new polymer light-emitting diode as a transmitter, we have achieved a record transmission speed of 10 Mb/s for a polymer light-emitting diode-based optical communication system with an orthogonal frequency division multiplexing technique, matching the performance of single carrier formats using multitap equalization. For achieving such a high data-rate, a power pre-emphasis technique was adopted. © 2014 Optical Society of America.

Quasi-pilot aided phase noise estimation for coherent optical OFDM systems

In this letter, a novel phase noise estimation scheme has been proposed for coherent optical orthogonal frequency division multiplexing systems, the quasi-pilot-aided method. In this method, the phases of transmitted pilot subcarriers are deliberately correlated to the phases of data subcarriers. Accounting for this correlation in the receiver allows the required number of pilots needed for a sufficient estimation and compensation of phase noise to be reduced by a factor of 2 in comparison with the traditional pilot-aided phase noise estimation method. We carried out numerical simulation of a 40 Gb/s single polarization transmission system, and the outcome of the investigation indicates that by applying quasi-pilot-aided phase estimation, only four pilot subcarriers are needed for effective phase noise compensation. © 2014 IEEE.

Unrepeatered DPSK transmission over 360 km SMF-28 fibre using URFL based amplification

Unrepeatered 42.7 Gb/s per channel RZ-DPSK transmission over standard SMF-28 fibre with novel URFL based amplification using fibre Bragg gratings is investigated. OSNR and gain performance are studied experimentally and through simulations. Error free transmission for 16 channels across the full C-band with direct detection was experimentally demonstrated for 280 km span length, as well as 6-channel transmission at 340 km and single-channel transmission up to 360 km (75 dB) without employing ROPA or specialty fibres.©2013 Optical Society of America.