4 January 2008 Encoding and transmission of orthogonally optical label switching using DQPSK payload and MD-RZ label
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Optical label switching (OLS) has been regarded as an efficient technique to route and forward IP packets transparently in the optical layer. In label switching system, orthogonal modulation has shown some advantages, such as its high spectral efficiency. One example is the combination of amplitude-shift-keying (ASK) label and differential phase-shift-keying (DPSK) payload. However, differential quadrature phase-shift-keying (DQPSK) payload has not been used in optical label switching system yet. In this letter, we propose and demonstrate a novel optical label switching scheme by the combination modified return zero (MD-RZ) and DQPSK for the first time. The transmitter is set up by cascading two phase modulators (PM) and one dual-arm LiNbO3 modulator (LN-MOD). The signal is first phase modulated by two PMs. The MD-RZ label is then impressed by the subsequent LN-MOD. Duty cycle and extinction ratio of the MD-RZ labels are tunable. The DQPSK payload can be used in a 20Gbit/s optical label switching system, with 2-bit per symbol modulation/demodulation. Within the network, the label information is read, processed and updated, a process known as label switching, until the burst reaches the desired egress edge node. The use of balanced detection is expected to improve performance for the payload. The transmission performance of 20Gbit/s DQPSK payload with 2.5Gb/s MD-RZ-ASK label is also analysed. MD-RZ labeling of a DQPSK payload has been shown to be a promising candidate for the implementation of OLS system.
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Yufeng Shao, Yufeng Shao, Shuangchun Wen, Shuangchun Wen, Lin Chen, Lin Chen, Yaoqiang Xiao, Yaoqiang Xiao, "Encoding and transmission of orthogonally optical label switching using DQPSK payload and MD-RZ label", Proc. SPIE 6837, Information Optics and Photonics Technologies II, 68370N (4 January 2008); doi: 10.1117/12.756289; https://doi.org/10.1117/12.756289

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