Novel schemes of optical power equalizer (OPE) and optical hard limiter (OHL) are presented, which base on quantum-dot
semiconductor optical amplifiers (QD-SOAs) and adopt a traveling-wave QD-SOA in each arm of Mach-Zehnder
interferometer (MZI). The function of power equalization and hard limitation can be realized respectively in a wide range
by setting the phase difference between two arms of Mach-Zehnder interferometer.
Optical packet switching (OPS), which transfers the switching function from electrical domain to optical domain and
provides the smallest switching granularity, is the most potential candidate of switching form in the future optical
networks. Optical code division multiplexing (OCDM) is the mostly practical all-optical processing technology at the
state of the art. The experiments of optical packet switching with optical code (OC) label have demonstrated the
switching capability and advantages. But the timing of erasing and inserting label, which is similar with the bit-serial
label processing, is the stringent requirement of this scheme. OCDM optical packet switching, which encodes the
payload directly and removes the label when the payload is recovered at the decoder, has no stringent timing requirement.
Multiple access interference (MAI) is the main factor degrading the performance of OCDM optical packet-switched
networks. In this paper, the effects of MAI are studied at the end of optical label path where the packets experience
multiple hops. For eliminating the end-to-end BER, the optical label paths need to be established in an optimum way and
the load are required to be balanced. One load-balancing algorithm based on the end-to-end BER of OCDM path is
proposed to improve the network performance.
This paper proposes an all-optical label processing scheme using multiple optical orthogonal codes sequences (MOOCS)
for optical packet switching (OPS) (MOOCS-OPS) networks, for the first time to the best of our knowledge. In this
scheme, the multiple optical orthogonal codes (MOOC) from multiple-groups optical orthogonal codes (MGOOC) are
permuted and combined to obtain the MOOCS for the optical labels, which are used to effectively enlarge the capacity of
available optical codes for optical labels. The optical label processing (OLP) schemes are reviewed and analyzed, the
principles of MOOCS-based optical labels for OPS networks are given, and analyzed, then the MOOCS-OPS topology
and the key realization units of the MOOCS-based optical label packets are studied in detail, respectively. The
performances of this novel all-optical label processing technology are analyzed, the corresponding simulation is
performed. These analysis and results show that the proposed scheme can overcome the lack of available optical
orthogonal codes (OOC)-based optical labels due to the limited number of single OOC for optical label with the short
code length, and indicate that the MOOCS-OPS scheme is feasible.
A novel scheme of optical packet power equalization is proposed by utilizing the gain characteristic of FP-SOA sensitive to input optical power. The steep gain descending curve with the carrier density provides that the high-power input optical signal obtains the low gain and the low-power one achieves the high gain. Real-time controlling mechanism according to input optical power is aborted in this scheme. The working principle of optical power equalizer based on FP-SOA is introduced in detail. The simulations show that 10 dB pulse peak power variation can be clamped in less than 1 dB. The impact of the injecting current, pulse width and pulse period are investigated and discussed.
A novel label abstraction and erasion scheme based on a FP-SOA is proposed for all-optical separation of the bit-serial label from payload and its performance is investigated by simulation. Fabry-Perot semiconductor optical amplifier (FP-SOA) is attractive not only due to simple fabrication without anti-reflection coating step but also due to its signal amplification capability and strong nonlinearity to perform all-optical label processing. Important features of this scheme are that it does not make use of any high-speed electronics and that only one device is needed. Using this scheme, label abstraction and erasion can be realized with the extinction ratio of 9.72 dB and 7.05dB, respectively. And the influence of pulse width ratio between the label and payload pulse on the extinction ratio is also investigated. We find that for a given case, there must be an optimized pulse width ratio to make the extinction ratio largest. It depends on working points of the label pulses and payload pulses in the gain curve.
A novel label erasion scheme based on a FP-SOA is proposed for all-optical separation of the subcarrier multiplexing
(SCM) label from payload and its performance is investigated by simulation. Fabry-Perot semiconductor optical
amplifier (FP-SOA) is attractive not only due to simple fabrication without anti-reflection coating step but also due to its
signal amplification capability and strong nonlinearity to perform all-optical label processing. Important features of this
scheme are that it does not make use of any high-speed electronics. Using FP-SOA as optical SCM label eraser,
more than 9db extinction ratio can be obtained. Meantime the payload can be amplified by more than 11dB.
In this scheme, FP-SOA acts as a low-pass filter as while as an amplifier.
Due to lack of optical random access memory (ORAM), fiber delay lines (FDLs) is a good approach to contention resolution in optical packet switching (OPS). For studying of the performance of FDLs in content resolution strictly, a model of optical packet switching with feedback FDLs is established. The packet loss probability and the average delay time are deduced in theory. The results indicate that FDLs can improve the packet loss probability dramatically in low load but tardily in high load. Under the condition of low load, the difference of the average delay time with the different number of FDLs or input / output fibers is very small. In high load, the average delay time decreases with the increase of the number of input / output fibers and increases with the increase of the number of FDLs.