Dynamic Brillouin gratings (DBGs), inscribed by co-modulating two writing pump waves with a bi-phase code, are analyzed theoretically, simulated numerically, demonstrated and characterized experimentally. A comparison is made between modulation by pseudo-random bit sequences (PRBS) and perfect Golomb codes. Numerical analysis shows that Golomb codes provide lower off-peak reflectivity, due to the unique properties of their cyclic auto-correlation function. Golomb coded DBGs can therefor allow for the long variable delay of one-time probe waveforms with higher signal-tonoise ratios, and without averaging. A figure of merit is proposed, in terms of the optical signal-to-noise ratio of reflected waveforms and the delay-bandwidth product of the setup. As an example, the variable delay of return-to-zero, on-off keyed data at 1 Gbit/s rate, by as much as 10 ns, is successfully demonstrated. The eye diagram of the reflected waveform remains open, whereas PRBS modulation of the pump waves results in a closed eye.

Date Published: 21 February 2014
PDF: 9 pages
Proc. SPIE 8998, Advances in Slow and Fast Light VII, 89980W (21 February 2014); doi: 10.1117/12.2047534

Published in SPIE Proceedings Vol. 8998:
Advances in Slow and Fast Light VII
Selim M. Shahriar; Frank A. Narducci, Editor(s)