We present a novel upstream burst-mode equalization scheme based on optimized SOA cascade for 40 Gb/s TWDMPON. The power equalizer is placed at the OLT which consists of two SOAs, two circulators, an optical NOT gate, and a variable optical attenuator. The first SOA operates in the linear region which acts as a pre-amplifier to let the second SOA operate in the saturation region. The upstream burst signals are equalized through the second SOA via nonlinear amplification. From theoretical analysis, this scheme gives sufficient dynamic range suppression up to 16.7 dB without any dynamic control or signal degradation. In addition, a total power budget extension of 9.3 dB for loud packets and 26 dB for soft packets has been achieved to allow longer transmission distance and increased splitting ratio.
Detailed numerical investigation of self-seeded colorless ONU transmitter using quantum dot (QD) SOA as the intensity modulator for symmetric 40 Gb/s TWDM-PON has been developed. It is shown that the QD SOA-based intensity modulator is able to support 10 Gb/s OOK upstream signal transmission with an optical extinction ratio of over 10 dB. Chromatic dispersion compensation free of 20 km passive transmission has been achieved for error free reception. Moreover, the system performance and power budget have been analyzed and discussed for different transmission distance and split ratio.
Wavelength tunable optical transmitter is an essential component for the newly standardized time and wavelength division multiplexed passive optical network (TWDM-PON), where tunable ONU with 10Gb/s bit rate is desired to provide 40Gb/s symmetric bandwidth. In this paper, a novel wavelength tunable optical transmitter is proposed by reusing legacy low speed multi-mode Fabry-Perot laser and connecting it with an integrated photonic chip with two coupled micro-ring resonators to generate a tunable single mode signal based on Vernier effect for 10Gb/s high speed modulation, which makes it as a promising solution for colorless ONU in future symmetric TWDM-PON.
Metro-access network is a newly emerged network which combines the traditional separated metro network and access network together into a converged system. It serves more users in a larger geographical area, meanwhile maintaining a simplified network hierarchy which inherits the low cost, large bandwidth, and high reliability of PON. In this paper, a novel remote node for metro-access converged network is proposed, which supports multi-type PON colorlessly, meanwhile maintains single specification for all subscribers. In addition, it saves nearly half of the spectrum resource in the metro part.
We propose a novel reconfigurable optical en/decoder to generate and recognize two-dimensional (2-D) optical
codes for coherent optical-code-division-multiple-access (OCDMA) application. The proposed device is based on
cascaded coupled micro-ring reflectors, which can enable simultaneous tuning of the fast wavelength hopping and
spectral phase encoding code patterns. The coding performance is verified by simulation.
We experimentally demonstrate the security vulnerability in the temporal phase coding single-user differential phase-shift
keying (DPSK) and code-shift keying (CSK) OCDMA systems with a DPSK demodulator. In the experiment, we
build up the 2.5Gbit/s DPSK- and CSK-OCDMA systems. In the systems, we use two 31-chip 640 Gchip/s
superstructured fiber Bragg grating encoders for the signal encoding. In the receiving side, we remove the decoders and
utilize the DPSK demodulator to detect the encoded signals directly. We successfully achieve the error-free BER
performance and obtaine the clear open eye diagrams using the detection without the proper decoding. It indicates the
existence of the eavesdropping vulnerability in the both systems. Furthermore, we also discuss the principle of DPSK
demodulation attack.
We propose and experimentally demonstrate a reconfigurable two-dimensional (temporal-spectral) time domain spectral
phase encoding (SPE) scheme for coherent optical code-division-multiple-access (OCDMA) application. The time-domain
SPE scheme is robust to wavelength drift of the light source and is very flexible and compatible with the fiber
optical system. In the proposed scheme, the ultra-short optical pulse is stretched by dispersive device and the SPE is
done in time domain using high speed phase modulator. A Fiber Bragg Gratings array is used for generating the two-dimensional
wavelength hopping pattern while the high speed phase modulator is used for generating the spectral phase
pattern. The proposed scheme can enable simultaneous generation of the time domain spectral phase encoding and
DPSK data modulation using only a single phase modulator. In the experiment, the two-dimensional SPE codes have
been generated and modulated with 2.5-Gb/s DPSK data using a single phase modulator. Transmission of the 2.5-Gb/s
DPSK data over 49km fiber with BER<10-9 has been demonstrated successfully. The proposed scheme exhibits the
potential to simplify the architecture and improve the security of the OCDMA system.
We have proposed and experimentally demonstrated an ultrafast optical pulse repetition rate multiplication technique
from a relatively slow optical pulse source at 1550nm based on reconfigurable time domain spectral amplitude/phase
filtering operation. In the proposed technique, a pair of dispersive fibers and a high speed electro-optical modulator
driven by a 40GHz pulse pattern generator that can be rapidly programmed are used to control the repetition rate. In the
experiment, repetition rate multiplication from 10GHz to a high speed repetition rate of 20GHz and 40GHz has been
successfully achieved by the proposed time domain spectral amplitude/phase filtering.
We demonstrate the security improvement using ±π/2-phase-shifted SSFBG encoder in time-spreading OCDMA.
Compared with conventional 0/π-phase-shifted SSFBG encoder, ±π/2-phase-shifted SSFBG encoder conceals code
pattern well in the encoded waveform. We also theoretically analyze and experimentally investigate the influence of
input pulse and the experimental measurement matches the calculated result very well.
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