A novel orthogonal modulation scheme of polarization-shift-keying label over vestigial sideband payload is proposed and experimentally demonstrated over a 43-Gb/s alloptical- label-switching transmission. With this scheme, a high extinction ratio of the label is reached, while a spectral efficiency of 0.8 b/s/Hz is achieved by weakening the imperfection of the high-speed pulse sequence in polarization modulation. Furthermore, this modulation scheme is relatively irrelevant with payload bit rate. The payload and label penalties after 80-km NZDSF fiber transmission and label erasure are 1.5 and 1 dB, respectively. The influence of filter center frequency offset is also investigated. Besides, a label rewriting method is introduced to simplify label processing in intermedia nodes. All these results show that this scheme can be a candidate technique for the next-generation optical network.

We propose and experimentally demonstrate a polarization shift keying label and a vestigial sideband carrier-suppressed return-to-zero payload scheme for a 43 Gbit/s all-optical label switching network. This scheme has a narrow channel bandwidth and a low penalty due to polarization mode dispersion impairments, which confirm it as a candidate technique for the next generation of optical networks.

A novel composite approach to generate ultra-wideband (UWB) doublet pulses in optical domain through an electrical Gaussian pulse is proposed and demonstrated in this letter. Two pulses with reversed polarity generated by polarization modulation are fed into a differential group delay device and a semiconductor optical amplifier (SOA) wherein the optical pulse profile is modified. Doublet pulses are obtained after optical–electrical detection due to gain saturation and recovery mechanism in the SOA. The fractional bandwidth of doublet pulses exceeds 180%, fulfilling the UWB requirements.

All-optical label switching (AOLS) is a potential technique which is introduced to fully use the bandwidth capacity in future optical networks and the packet operations are mostly carried out in the optical layer. The key issue in the AOLS approach is the method of coding the optical label onto the packet as it directly determines the structure and the performance of the optical core router as well as the channel bandwidth efficiency and the transmission quality of the packet and its label. With the bit rate increasing above 40Gb/s, new labeling scheme is needed to enhance the spectral efficiency. In this paper, recent advanced labeling schemes for future high speed AOLS network are reviewed, especially the new schemes demonstrated in Tsinghua University, China. Two novel labeling scheme based on vestigial sideband (VSB) modulation are mainly introduced both in principle and experiment. One is compact wavelength labeling scheme which achieves high spectral efficiency since the wasteful double sideband of 40Gb/s has been reduced to vestigial sideband. This scheme can be easily carried out by using optical filters. Another is polarization shift keying scheme with VSB payload which has high spectral efficiency near to 0.8bit/s/Hz. This scheme utilizes two polarization orientations to carry the label signal and causes little distortions between the label and payload. And this scheme is also independent of the payload bit rate which is a good character for future networks. Both the two schemes have little power penalties after long distance SMF transmission and are promising to be used in beyond 40Gb/s optical networks.

A novel scheme based on 40Gb/s vestigial sideband modulation for optical payload and label multiplex and separation in all optical label switching (AOLS) networks is firstly proposed and experimentally demonstrated. The payload is combined and separated with wavelength labels by optical filters. The experiment results show that after label separation, the power penalties of payload and label are both very little. The influence of the wavelength difference between label and payload is also discussed. The power penalty of payload can be less than 1dB as long as the wavelength difference is larger than 0.1nm. This scheme highly reduces the channel bandwidth of payload and label and is proposing to be used in future optical Internet.