Bit Error Rate Measurements of All-Optical Flip-Flop Operations of a 1.55-μm Polarization Bistable VCSEL

We measured the bit error rate (BER) of all-optical flip-flop operations using a 1.55-μm polarization bistable vertical-cavity surface-emitting laser (VCSEL). Polarization bistable flip-flop operations were obtained by injecting optical set and reset pulses with independently adjusted wavelengths toward the two VCSEL lasing modes, whose polarizations are orthogonal to each other. Acquired waveforms showed clearly opened eyes, and BERs less than 1 × 10
^-9
were measured up to 1 Gb/s although the optical set and reset pulse power was much lower than the VCSEL output power. We also demonstrated all-optical flip-flop operations by injecting optical set and reset pulses with the same wavelength, which were generated by a single laser diode. In this case, we obtained polarization bistable flip-flop operations up to 500 Mb/s with almost the same BER values that were obtained when the wavelengths of the set and reset pulses were adjusted independently. The optical input pulse powers were higher than for the case using input pulses with two different wavelengths, but still lower than the VCSEL output power.