All-optical passive format conversions from RZ and CS-RZ signals to NRZ signals at 40Gb/s

Abstract

All-optical format conversions from return-to-zero (RZ) and carrier suppressed RZ (CS-RZ) to non-return-to-zero (NRZ) are demonstrated with a temperature-controlled all-fiber delay interferometer (DI) and narrow-band filters, at 40 Gb/s. The format conversion processes are analyzed in frequency domain. By properly controlling the DI and the tunable filters, for the RZ input, NRZ signal can be achieved at the carrier wavelength from one of the DI output ports; and for the CS-RZ input, NRZ signals can be achieved at two different wavelengths simultaneously from two output ports of the DI. The operation principle is analyzed with spectra evolution analysis. The power penalties are 1.5 dB and 1.8 dB, for RZ and C-RZ to NRZ conversions, respectively.