We propose and evaluate an all-optical 2-bit header recognition and packet switching method using two 1.55-µm polarization bistable vertical-cavity surface-emitting lasers (VCSELs) and three optical switches. Polarization bistable VCSELs acted as flip-flop devices by using AND-gate operations of the header and set pulses, together with the reset pulses. Optical packets including 40-Gb/s non-return-to-zero pseudo-random bit-sequence payloads were successfully sent to one of four ports according to the state of two bits in the headers with a 4-bit 500-Mb/s return-to-zero format. The input pulse powers were 17.2 to 31.8 dB lower than the VCSEL output power. We also examined an extension of this method to multi-bit header recognition and packet switching.
Bit error rates (BERs) of all-optical flip-flop operations with AND-gate functionality using a 1.55-µm polarization bistable vertical-cavity surface-emitting laser (VCSEL) were measured. Optical data pulses of a 500-Mb/s return-to-zero pseudo-random bit-sequence were used. The best BER we obtained was 5.00 × 10 −9 and the eye diagram was clearly open. Inputpulse power was about 17 dB lower than VCSEL output power. From the BER variation for the set-pulse power under fixed data-pulse power, we found that fluctuations in the switching threshold and power of AND pulse (combination of data and set pulses) affect the BER. We also evaluated the BER of memory operations.
Abstract:We investigated all-optical flip-flop operations with AND-gate functionality by injecting data and set inputs with different wavelengths to a 1.55-µm polarization bistable vertical-cavity surface-emitting laser. Control of the phase difference between the two inputs is not needed for stable operation, which differs from the same wavelength case we have used thus far. Thus, this proposed method will simplify all-optical signal processing systems. The wavelength difference dependencies of the switching power and the timing jitter of the polarization switching were measured for 1-ns data pulses. For 2 GHz wavelength difference, the data (set) pulse power was about −20 (−14) dBm and the timing jitter was about 110 ps. The BER was about 8 × 10 −3 .
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