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Spectral phase coding by using 0/π-phase-shift and ±π/2-phase-shift are thoroughly studied. The security vulnerability and improvement are analysed by evaluating the encoded signal. ίπ/2-phase-shift spectral phase coding can guarantee the security by hiding the optical code in the encoded signal. In addition, coding performance of both spectral phase coding techniques is investigated by measuring...
We propose a novel optical encoding scheme based on spectral phase encoding, in which optical codes are randomly selected from a code set for code hopping. The security performance is analysed. It can achieve the identical security level with short hopping pattern, efficiently improving the system resources.
A novel spectral phase encoding scheme by using ±π/2 phase shift in the en/decoding is proposed. The scheme can submerge the code information in the encoded signals well, improving the security against code extraction from the encoded signals. Furthermore, based on the theoretical analysis, the coding performance of the proposed scheme is guaranteed.
In this paper we propose a scheme to compare any two encoded optical signals by using differential detection and identify optical code sequence in the encoded data stream. Furthermore, we propose an algorithm to recover the original data from the derived optical code sequence. This scheme can be used to analyze the security performance of multi-optical-code based secure optical communication systems...
We develop the novel ±π/2-phase-shifted SSFBG en/decoders (31-chip 640Gchip/s) and verify the improved security performance. We also demonstrate the mixed use of 0/π- and ±π/2-phase-shifted SSFBG en/decoders in the 4-user 10Gbps/user OCDMA system.
We experimentally demonstrate the security improvement using ±π/2-phase-shifted SSFBG encoder in time-spreading OCDMA. Compared with conventional 0/π-phase-shifted SSFBG encoder, ±π/2-phase-shifted SSFBG encoder conceals code pattern well in the encoded waveform. We also investigate the influence of input pulse and the experimental measurement matches the calculated result very well.
We experimentally demonstrate security vulnerability in the temporal phase coding single-user DPSK- and CSK-OCDMA systems with a DPSK demodulator. In the systems without proper decoding, error free BER performance and clear open eye diagrams indicate the eavesdropping possibility for both systems. We also discuss the principle of DPSK demodulation attack.
The existence of dips in the waveform encoded by 0/π-phase-shifted superstructured fiber Bragg grating (0/π -SSFBG) allows eavesdroppers to extract code sequence straightforwardly. In this letter, the code extraction technique for 0/π-SSFBG is summarized and demonstrated. To address this security issue, we propose using ±π/2-phase-shifted ±π/2-SSFBG as encoder/decoder to improve security in time-spreading...
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