In incoherent-injected WDM-PONs, it is shown through simulations and experiments that Flat-band athermal AWGs
with channel spacing of 100GHz have improved performance in terms of BER than their Gaussian-shape counterpart,
due to the effect of signal filtering. At a BER of 10-9, the power penalty is 2 dB for Flat-band AWGs and more than 4
dB for Gaussian AWGs, which do not reach the required BER. In addition, the effect of AWG detuning in the WDM-PON
systems is investigated. It is shown that by detuning the two Flat-band AWGs by 40GHz from their center
wavelength, an additional 0.5dB power penalty is induced.
We demonstrated an ultra-broadband wavelength converter based on co-polarized dual-pumping four-wave mixing
technique in a dispersion-flattened photonic crystal fiber. Over 380-nm wavelength conversion range from 1260 nm to
1640 nm has been achieved. By sweeping the wavelengths of the second pump laser, we have obtained the relationship
between the wavelength conversion efficiency and the converted data signals, which are consistant with our theoretical
analysis. The OSNR of the converted data signals are up to 30 dB.
We have designed, fabricated and characterized self-assembled InAs/InGaAsP QD-waveguide devices around 1.55 μm.
In order to obtain optimal performance, we have investigated several QD-based semiconductor optical amplifiers
(SOAs) / lasers with different core geometry and doped profiles. To make the fair comparison between QD-SOA and
QW-SOA, InAs/InGaAsP QW-SOAs with the same structure and the doped profiles have been designed and
characterized. The experimental results indicate the QD-SOA is much better than QW-SOA in term of optical spectral
bandwidth, temperature sensitivity and output power stability. The
3-dB and 10-dB bandwidths of the amplified
spontaneous emission (ASE) spectra of the QD-SOA are 150 nm and 300 nm around 1520 nm. By using CW pump and
probe signals we have demonstrated a non-degenerated four-wave mixing (ND-FWM) process and the experimental
results indicate that the asymmetry of the FWM conversion efficiencies is eliminated by using the QD-SOA. To make
use of the inhomogeneous broadening which is one of the specific properties of QD waveguide devices, we have
designed and investigated the QD-based multi-wavelength semiconductor laser. A stable multi-wavelength laser output
with a 93-channel multi-wavelength laser with maximum channel intensity non-uniformity of 3-dB were demonstrated
on the basis of a single InAs/InGaAsP QD F-P cavity chip. All channels were ultra-stable because of the inhomogeneous
gain broadening due to statistically distributed sizes and geometries of self-assembled QDs.
In this paper, a three-stage packet switch architecture is implemented consisting of a reconfigurable optical center stage surrounded by two electronic buffering stages grouped into sectors to ease contention. A Flexible Bandwidth Provision algorithm is used to change the configuration of the optical center stage to form the requested bandwidth desired by incoming traffic. The switch is modeled by a bipartite graph built from the service matrix. The bipartite graph is decomposed by solving an edge-coloring problem and the resulting permutations are used to configure the central stage removing the requirement for a per-time slot scheduler.
Flexible Bandwidth Provision (FBP) algorithm requires dynamically reconfigurable technology readily available in programmable logic devices. The designed packet switch being a collection of discrete entities is most easily implemented on separate programmable logic devices forming electronic “islands” interconnected by photonics technology. The demonstrator itself contains 64 inputs and 64 outputs with reconfigurable central stage crossbars. The switch is a collection of input and output sectors each implemented on a single FPGA. Each sector is an 8 x 8 sub-switch with shared buffer memory. The interface between the sectors and the central stage will use VCSEL technology for O-E-O conversion. The input sectors together with the central stage form the adaptive portion of the switch configured by an embedded soft-core processor implementing the FBP algorithm of which is entity are located on an Ethernet local area network.
This switching architecture has also been simulated and results show that this architecture result in a dramatic reduction of complexity, at the price of only a modest spatial speed-up (<2).