Quantum noise ultimately restricts the transmission distance in fiber communication systems using optical amplifiers. This paper investigates the quantum-noise-limited performance of optical binary phase-shift keying transmission using gain-saturated phase-sensitive amplifiers (PSAs) as optical repeaters. It is shown that coherent state transmission, where ultimately clean light in the classical sense is transmitted, and endless transmission, where the transmission distance is not restricted, are theoretically achievable under certain system conditions owing to the noise suppression effects of the gain-saturated PSA.

The extended binary phase shift keying (EBPSK) transmission system with ultra narrow bandwidth has excellent BER performance, which raises many doubts with the researchers. Therefore, on the premise of the existence of a special filter that can transform the modulated phase information into amplitude information, the theoretical BER formula of EBPSK system in Additive White Gaussian Noise (AWGN) channel has been deduced. This paper gives the theoretical values of the parameters in the above BER formula and discusses the effects of parameters on BER firstly. Then the paper shows that the special impacting filter satisfies the above assumption, therefore, in the frame of binary detection theory, the excellent performance of high-efficiency EBPSK system can be explained and the correction of the theoretical BER formula can be validated.

A mixed-mode high-speed binary phase-shift keying (BPSK) demodulator for IEEE802.15.3c mm-wave wireless personal area network (WPAN) application is realized with 0.18-µm CMOS process. The proposed demodulator scheme does not require any analog-to-digital converters (ADC) and, consequently, can have advantages over the conventional schemes for high-data-rate demodulation. The demodulator core consumes 53.8 mW from 2.5-V power supply while the chip area is 380500 µm2. The fabricated chip is verified by 60-GHz wireless link tests with 1.6-Gb/s data.

All-optical wavelength conversion and modulation format conversion will be needed in the next generation high-speed optical communication networks. We have proposed and successfully demonstrated the error free operation of all-optical modulation format conversion from NRZ-OOK to RZ-BPSK using SOA based MZI wavelength converter. In this paper, we experimentally investigate the wavelength conversion characteristics of the proposed NRZ-OOK/RZ-BPSK modulation format converter. The results show that error free modulation format conversion is possible over the entire C band.

Optical processing with efficient coding is expected in photonic label routing network. We consider optical codes encoded in the time and spectral domains. Wavelength-selective devices are useful for effective processing of such optical codes. In this study, collinear acoustooptic (AO) switches are investigated as a constituent elements of a wavelength selective correlator for optical BPSK codes. It is theoretically shown that the number of optical codes that can be distinguished is 2Nt-1, where Nt is the bit number of optical pulses. The device can also be used for recognition of codes encoded in time and spectral domains. Crosstalk in code recognition is discussed with numerical analysis considering AO filtering characteristics for optical processing with collinear AO devices.

A key element in the CDMA transmission is DS spreading. Spreading in a DS/SSMA system are provided in two categories-synchronization and data. For synchronization sequences, good auto-correlation and cross-correlation properties are required in order to guarantee fast acquistion with a minimum false alarm probability. On the other hand, the auto-correlation property may not be so important in data spreading since synchronization is obtained by synchronization spreading. In this paper we provide a set of synchronization sequences and a set of data sequences--each a set of binary N-tuples--that have the necessary correlation constraints.