Abstract

With the development in the area of femtosecond pulse generation by mode-locked lasers,¹ ultrafast all-optical code-division multiple access (CDMA) networks that can provide more address sequences and simultaneous users than the present CDMA networks^2-4 become increasingly feasible. Using a CDMA network with a data rate 100 Mbit/s and pulse (chip) width 100 fs as an example, the sequence length is 100,000. Both the numbers of address sequences and simultaneous users are~317 when prime code² is used. However, the corresponding length of delay for such a narrow pulse is in the order of µm. Therefore, the decoders and encoders of the next generation CDMA networks need to be fabricated in waveguides. The problems that include the power loss, size, delay length, and programmability have to be addressed. Prime networks,^2,3 which generate and select codewords by a parallel combination of fiber-delays, and 2ⁿ networks⁴ which generate codewords by a serial combination of 2×2 couplers and select codewords in a parallel fashion, are not suitable for waveguide implementation.

© 1992 Optical Society of America