A fast tunable parallel optical delay line

We demonstrate a new rapidly tunable parallel optical delay line (PODL) capable of accessing multiple high speed OTDM channels with very low latency using only one modulator operating below baseband. The PODL uses a new parallel compression scheme to rapidly tune pulses into different time slots within an OTDM frame. Since the modulator bandwidth is actually lower than the baseband of the output data, regardless of the chosen timeslot, the PODL offers an advantage over the previous tunable serial techniques in terms of simplicity and scaling towards higher optical baseband bit rate. In addition, the use of only one modulator requires only one polarization controller at the input of the PODL to optimize coupling with the modulator, and no polarization controller or polarization maintaining fiber are needed within the delay structure. The results from our demonstration of the PODL show that fast tuning among multiple high bit rate OTDM channels can be achieved and practically implemented.