A novel all-optical 40Gbit/s NRZ-to-RZ data format conversion scheme based on sum-frequency generation (SFG) interaction in a periodically poled LiNbO³ (PPLN) waveguide is presented for the first time, using a Mach-Zehnder interferometer (MZI). The conversion mechanism relies on the combination of attenuation and nonlinear phase shift Φ_NL induced on the signal field. The performance of the conversion is numerically evaluated, with the result showing that it is more effective to yield Φ_NL when appropriately phase mismatched for SFG process but Φ_NL≈0 when quasi-phase-matching (QPM). Compared with the cascaded second-order nonlinear interactions (SHG+DFG) with the influence of walk-off effect, a high conversion efficiency and good performance are achieved with peak power 500mw and width 2ps of the pump, which can be used in super high-speed situation (40Gbit/s and above). Finally, the inverse process of SFG and corresponding walk-off effect are analyzed and the optimum arrangement of power is proposed, showing that proper power, pump width, and waveguide length are necessary for achieving a satisfied conversion effect.

Date Published: 28 January 2006
PDF: 8 pages
Proc. SPIE 6025, ICO20: Optical Communication, 60250T (28 January 2006); doi: 10.1117/12.667020

Published in SPIE Proceedings Vol. 6025:
ICO20: Optical Communication
Yun-Chur Chung; Shizhong Xie, Editor(s)