Demonstration of return-to-zero signaling in both OOK and DPSK formats to improve receiver sensitivity in an optically preamplified receiver

Summary form only given. We demonstrate record receiver sensitivities at 1O Gb/s using RZ signaling and optimization of the optical filter bandwidths (for a Fabry-Perot optical filter and fixed 10 GHz electrical filter bandwidth). Two different modulation formats are considered: on-off keying (OOK) and differential phase shift keying (DPSK). To the best of our knowledge, this is the first demonstration of encoding phase information on RZ optical pulses to be subsequently decoded in a DPSK demodulator, and as such we christen the term RZDPSK to describe this format. Direct comparison with NRZ signaling and constant intensity DPSK reveals an improvement of about 1 dB in receiver sensitivity.