We propose and demonstrate all-optical format conversion from nonreturn-to-zero differential phase-shift-keying
(NRZ-DPSK) to return-to-zero binary PSK (RZ-BPSK) at different bit-rates, using a tunable band-pass filter, a
semiconductor optical amplifier (SOA) fiber ring laser and an SOA based Mach-Zehnder interferometer (SOA-MZI).
The filter acts as the DPSK demodulator and also as the differential decoder. It converts the NRZ-DPSK into the RZ
signals, which is equivalent to the data information before differential encoding. The SOA fiber ring laser is used to
recover the clock signals from the demodulated RZ signals at different bit-rates. In the subsequent SOA-MZI, the RZ
signal is used to modulate the recovered clock signal which is synchronous to the demodulated RZ signal. Thus, the
amplitude information is encoded onto the phase of the clock signal, through cross gain modulation (XGM) and cross
phase modulation (XPM) effects in the SOA-MZI. The converter can be operated at flexible bit-rates and used as the
interface between long-haul WDM and OTDM systems.
We propose and demonstrate simultaneous multiple dense wavelength division multiplexing (DWDM) channels
optoelectronic non-return-to-zero (NRZ) to return-to-zero (RZ) regenerative format conversions based on a single phase
modulator (PM) and a fibre delay-interferometer (DI). The PM is driven by a local RF clock signal, and the DI with free
spectral range (FSR) equals to the channel spacing is used to extract the chirps induced by the phase modulation, for all
the channels at the same time. Since the original carriers are suppressed to some extent while the chirps are extracted,
thus the NRZ-to-RZ conversions can be achieved with regeneration. The proposed multi-channels format conversions are
successfully demonstrated at 16*10 Gb/s, with channel spacing of 100GHz. Bit error ratio (BER) measurements show
3.5 and 4.2 dB penalty improvements for 50 and 75 km transmission without dispersion compensation, respectively.
In this paper we present our study of all optical label encoding and ultrafast processing to route packets through optical
networks. Our investigations include new network topologies, novel photonic components and performance analysis. We
propose a <i>label stacked</i> packet switching system using spectral amplitude codes (SAC) as labels. We have developed
enabling technologies to realize key photonic components for generation, correlation (identification) and conversion
(swapping) of SAC-labels. We generate and identify the labels with fibre Bragg gratings (FBGs) encoders used in
transmission. Furthermore, we demonstrate a static, all-photonic code-label converter based on a semiconductor fiber
ring laser that can be used for label swapping of SAC-labels. We also address the design of dedicated receivers for
optical burst detection. For this, we propose a novel architecture for a burst mode receiver module. In the system studies,
we have shown by simulations that the throughput of standard Ethernet passive optical networks (E-PONs) can be
substantially increased by the use of data encoded with SACs to achieve optical code division multiple access over
passive optical networks (OCDMA-PONs). In the paper, we present recent results for all of these photonic technologies
and we discuss how they can enable flexible packet switched networks.