50 km bidirectional FTTH transmission comparing different PON standards

In this paper, a bidirectional Fiber To The Home (FTTH) is proposed where WDM transmitter is used as a seeding source with wavelength of 1550 nm. The system utilizes a Travelling wave Semiconductor Optical Amplifier (TSOA) with injection current 0.15A. 50 km range FTTH architecture is demonstrated for both downstream and upstream channels. We investigated the impact of different data rates on upstream and downstream data. The BER results show that the performance of our scheme is good for 10 Gbps system for downstream transmission as it accommodates 64 ONUs. From simulation results show the BER of 9.95e-009 is reported at 15 Gbps but only in case of 32 ONUs. Similarly, in case of upstream transmission, Q-Factor of 15.04 dB is reported for 32 ONUs. So this scheme is a practical solution to meet the data rate of the optical links simultaneously in tomorrow's PON access networks.     

Simulation of Fiber to the Home at 10 Gbit/s using GE-PON architecture

In this paper, a fiber communication system is employed using Giga Ethernet Passive Optical Network (GE-PON) architecture. In this architecture an optical fiber is employed directly from a Central Office to the home. A 1:8 splitter is used as a PON element which establishes communication between a Central Office to different users. The architecture has been investigated for different lengths from a Central Office to the PON in terms of BER. For 10 Gbit/s system the plots between the BER and transmission distance are plotted and it are seen that as the distance increases beyond the 15 km the BER is increased very sharply. The results in the form of voice and data spectrum for different users of FTTH with GE-PON architecture are shown.     

Simulation of FTTH at 10 Gbit/s for 8 OTU by GE-PON Architecture

In this paper a fiber communication system is employed using Giga Ethernet Passive Optical Network (GE-PON) architecture. In this architecture an optical fiber is employed directly from a Central Office to the home. A 1:8 splitter is used as a PON element which establishes communication between a Central Office to different users. In this paper GE-PON architecture has investigated for different lengths from a Central Office to the PON in the terms of BER. For 10 Gbit/s system the plots between the BER and transmission distance is plotted and it is seen that as the distance increases beyond the 15 km the BER is increased very sharply. Results in the form of Voice and Data spectrum for different users of FTTH with GE-PON architecture are shown.     

Low cost solution to high capacity 32 × 32 channel FTTH duplex link employing triple play services

In this paper, low cost solution based on RSOAs is proposed for a high capacity 32 × 32 channel, 20 km, FTTH duplex link employing triple play services. Here, downstream transmitters generate a 2.5-Gbps NRZ signal which is routed to both receivers and RSOA-based upstream transmitters. The RSOA modulates this signal with a 1.25-Gbps NRZ signal that effectively overwrites the downstream signal and then it is transmitted back over the same 20 km of bidirectional fiber, where it is routed to receivers at the CO. The proposed model completely eliminates the requirement of separate lasers for upstream communication which makes the system very cost effective. The high-pass filtering effect of the RSOA becomes predominant at higher input powers which has been used as an advantage here to effectively suppress the downstream signal. The impact of RSOA input power and extinction ratio of the downstream signal have been investigated and reported.     

Performance evaluation of bi-directional passive optical networks in the scenario of triple play service

In this paper, the performance of bi-directional passive optical network (BPON) has been evaluated and compared at different bit rates in the scenario of triple play service. The triple-play service is realized as a combination of data, voice and video signals. This architecture is investigated for symmetrical data traffic for uplink and downlink transmission and its performance is also evaluated in terms of Q-factor and eye height at different transmission distance. The Q-factor results show the acceptable performance at 10 Gbps data rate for downstream and upstream transmission, as it accommodates 128 optical network units (ONUs). Further the proposed system's performance is compared with the current state-of-the-art PON architectures.     

Adding channels with PSBT format at 40 Gbit/s in an existing 10 Gbit/s optical network

Until recently, the wavelength-division-multiplexed (WDM) transmission system has reached record capacities and distances due to innovations such as FEC (Forward Error Correction), distributed Raman amplification, new transmission fiber and advanced optical format. Optical-communication systems exclusively employed conventional On-Off Keying signals in either Non-Return-To-Zero (NRZ) or Return-To-Zero (RZ) format. Recently a number of advanced modulation formats have attracted attention. Some of these formats carry information through On-Off-Keying but also modulate the optical phase in order to enhance the robustness of signal to chromatic dispersion, optical filtering and non-linearities. Through extensive sets of simulation results, we showed that it is possible to replace a channel with higher bit-rate on existing DPSK or OOK at 10Gbit/s transmission link. Duobinary formats are ideal candidates to do it and are known for their low spectral range and high tolerance to residual chromatic dispersion. These particularities make them very attractive for both high bit rates and high distance-transmissions. Today, Phase Shaped Binary Transmission (PSBT) is considered as being the promising format for the deployment of 40Gbit/s technology on existing links at 10Gbit/s WDM long haul transmissions.     

Si-based near infrared photodetectors operating at 10 Gbit/s

We report on fast p-i-n near infrared photodetectors in pure germanium on silicon. The diodes were fabricated by chemical vapor deposition at 600 °C followed by thermal annealing at 900 °C. We also verified that bypassing the thermal treatment did not have significant effects on the resulting crystal quality, allowing to considerably reducing the thermal budget hence simplify the integration with silicon. We demonstrate the operation of photodiodes with responsivities of 0.4 and 0.2 A/W at 1.3 and 1.55 μm, respectively, as well as open-eye diagrams at 10 Gbit/s.     

RZ-DPSK transmission at 80 Gbit/s channel rate using in-line semiconductor optical amplifiers

We numerically demonstrate the feasibility of return-to-zero differential phase-shift keying transmission at 80 Gbit/s channel rate using cascaded in-line semiconductor optical amplifiers.     

Limitation in the intrinsic method of EDFA gain optimization for 32 × 40 Gbit/s WDM systems

The gain flattening of the erbium doped fiber amplifier (EDFA) is one of the most important aspects in the EDFA which the gain is wavelength dependent. For the first time the limitation of EDFA gain optimizing for a 32-channel wavelength division multiplexing (WDM) systems is investigated and reported in this paper. In a 32-channel WDM system the most favorable flatness gain achieved was 23.16 ± 1.51 dB with an average noise figure of 5.70 dB. This outcome proposes that the method does not achieve a uniform spectral gain in a 32-channel WDM system that incorporates a bandwidth of around 25 nm. Based on the simulation results the intrinsic optimization of EDFA causes the poor SNR and peak signal power with great variation over a transmission distance of 480 km single mode fiber.     

1 Gbit/s transmission over step-index plastic optical fiber using an optical receiver with an integrated equalizer

A single chip optical receiver with an integrated large-diameter photodiode, transimpedance amplifier, two stages active equalizer, post amplifier and 50 Ω driver is used for gigabit transmission over PMMA step plastic optical fiber (SI-POF). The large-diameter photodiode with an antireflection coating optimized for red light. The integrated equalizer enables the presented optical receiver to reach 1 Gbit/s over 50 m SI-POF at bit error ratio of 10^− 6. An error free (< 10^− 9) 1 Gbit/s data rate over 40 m standard PMMA step-index plastic optical fiber is also achieved.     

Analysis of 2.5 Gbit/s GPON downlink optical-receiver performance

In the gigabit-capable passive optical network (GPON) optical communication system, the selection of fiber and system performance-analysis is the key links for the realization of system function. Especially the characteristic budget and parameter setting of downlink receiver are topped the list. The analysis of receiver power penalty can reduce the influence on receiver sensitivity and bit error rate (BER) that caused by waveguide dispersion and pulse widening. This article will simulate the performance of GPON downlink receiver, then analyze typical characteristics such as Four Wave Mixing (FWM), Erbium-Doped Fiber Amplifier (EDFA), system eye pattern and Q factor and so on, so as to validate the feasibility of the optical downlink.     

Ultra-fast 160:10 Gbit/s time demultiplexing by four wave mixing in 1 m-long B2O3-based fiber

One meter-long spool of bismuth oxide-based fiber, with nonlinear coefficient of 1250 W⁻¹ km⁻¹, is used to realize an optical 160-to-10 Gbit/s demultiplexer based on four wave mixing. Bit-Error-Rate measurements demonstrate a demultiplexing penalty lower than 2 dB confirming the suitability of bismuth oxide-based fiber for 160 Gbit/s all-optical processing.     

Simulation analysis of crosstalk among channels with fiber Raman amplifiers at 10 Gb/s

We have investigated the effects of crosstalk in fiber Raman amplifiers (FRAs) by propagating signals through the Raman fiber. We have observed that quality factor reduces for lesser channel spacing. We have able to propagate the signals in two channels with spacing of 20 GHz and quality factor above 25 dB was obtained. The effect of signal input power and injected pump power on crosstalk and signal interference ratio (SIR) has analyzed. It is observed that the signal gain and the injected pump power should be limited to the value well below the threshold of Raman amplification to ensure small crosstalk and high SIR. The effect of Raman fiber length on crosstalk is also studied and it is observed that for high values of Raman fiber length, SIR reduces considerably.     

Multi-wavelength conversion at 10 Gb/s using cross-phase modulation in highly nonlinear fiber

In this paper we demonstrate a technique of signal wavelength conversion via cross-phase modulation (XPM)-induced nonlinear coupling among a 10 GHz return-to-zero (RZ) signal and a continuous wave (CW) carrier co-propagating in dispersion-shifted (DS) highly nonlinear fiber (HNLF). The wavelength conversion bandwidth up to ±20 nm was achieved experimentally and potential extension was verified by numerical simulations. The principle can easily be extended to 40 Gb/s and used as polarization insensitive all-optical wavelength converter.     

All-optical clock recovery of 20 Gbit/s NRZ-DPSK signals using polarization-maintaining fiber loop mirror filter and semiconductor optical amplifier fiber ring laser

All-optical clock recovery (CR) from 20 Gbit/s nonreturn-to-zero differential phase-shift-keying (NRZ-DPSK) signals are demonstrated experimentally by using a polarization-maintaining fiber loop mirror filter (PMF-LMF) and a semiconductor optical amplifier (SOA) fiber ring laser. Only by adjusting polarization controller (PC), NRZ-DPSK signals were conveniently and fast converted to pseudo return-to-zero (PRZ) signal via PMF-LMF. Then the PRZ signals are injected into the SOA fiber laser for CR. The recovered clock signals is with the extinction ratio (ER) of 10 dB and the root-mean-square (RMS) timing jitter of 750 fs in 2³¹ − 1 long pseudorandom binary sequence (PRBS) NRZ-DPSK signals measurement. Moreover, the broad wavelength tunability of recovered clock stemmed from the use of SOAs as modulator and the gain medium are shown too.     

Secure authentication scheme for 10 Gbit/s Ethernet passive optical networks

With the development of access network, 10G EPON has gained more and more attention. As its topology structure is point-to-multi-point and the downstream data is broadcasted, it will suffer from eavesdropping and masquerading attack. To eliminate these safety threats, this paper proposes an integrated security scheme including a bilateral authentication method and an encryption algorithm combined with one-way hash function. The authentication method can verify OLT and ONU during the registration process, preventing illegal users joining the network, and safely establish a secret key used for encrypting as well. The proposed scheme's security is based on the computational Diffie–Hellman assumption and the target collision resistant hash functions. The simulation results indicate that this mechanism is more suitable for practical use.     

The analysis of the error statistics in a 5 × 40 Gbit/s fibre link with hybrid amplification

We quantify the error statistics and patterning effects in a 5 × 40 Gbit/s WDM RZ-OOK SMF/DCF fibre link using hybrid Raman/EDFA amplification. By extensive use of a numerical model, we determine how the error statistics change with the transmission distance. This knowledge is used as a basis for a constrained coding technique in order to improve the transmission error rate. We propose an adaptive constrained code for mitigation of the patterning effects and demonstrate that this approach can substantially reduce the bit error rate (BER) even for very large values of the channel BER (BER > 10^− 1). The proposed technique can be used in combination with forward error correction schemes (FEC) to extend the range of channel BERs that an FEC scheme is effective over.     

Experimental demonstration on 40 Gbit/s all-optical multicasting logic XOR gate for NRZ-DPSK signals using four-wave mixing in highly nonlinear fiber

We propose and demonstrate all-optical multicasting logic XOR gate for non-return-to-zero differential phase-shift keying (NRZ-DPSK) signals by using non-degenerate four-wave mixing (FWM) in a highly nonlinear fiber (HNLF). Theoretical analysis regarding the operation principle of NRZ-DPSK logic XOR gate is clearly described by deriving an analytical solution under the non-depletion approximation. The NRZ-DPSK logic XOR operation is attributed to the linear relationship of complex amplitudes between converted idlers and input NRZ-DPSK signals. By using three non-degenerate FWM processes in an HNLF, 40 Gbit/s all-optical multicasting logic XOR gate for NRZ-DPSK signals are successfully demonstrated in the experiment.     

Analysis of modulation format in the 40 Gbit/s optical communication system

Three different modulation formats including nonreturn-to-zero (NRZ), return-to-zero (RZ), carrier-suppressed return-to-zero (CS-RZ) and the differential phase keying (DPSK) modulation format of each code are introduced in the article. A method of their modulated signal generation with computer is described, and a comparison of their spectra and waveforms is made. The 40 Gbps signal transmitted in 200 km G.652 fiber by way of single channel with erbium-doped-fiber-amplifier (EDFA) is simulated for these three formats. The ability of anti-dispersion and anti-PMD is analyzed. It is shown that RZ and CS-RZ formats are more tolerant than NRZ format in the same conditions.     

Optical 3R regeneration of 40 Gbit/s degraded data signals

A 40 Gbit/s optical 3R regenerator is proposed and demonstrated. The 3R regenerator consists of a dual-ring injection mode-locked fiber ring laser as the clock recovery module and an electroabsorption modulator (EAM) as the decision gate. The clock recovery module extracts the optical short pulse clock with low timing jitter from degraded 40 Gbit/s optical data streams, while the decision gate restores their signal quality. A numerical model describing the cross-absorption modulation effect in a bulk EAM is developed to explore the operating conditions, such as bias voltage, pump signal power. The timing jitter tolerance for the EAM optical gate is also investigated. Significantly improvement of BER is obtained from 40 Gbit/s RZ signals which are degraded by polarization mode dispersion or chromatic dispersion.