Conversion of RZ-OOK to RZ-BPSK by XPM in a Passive AlGaAs Waveguide

The conversion of data modulation format from 10-Gb/s return-to-zero on-off keying (RZ-OOK) to 10-Gb/s RZ binary phase-shift keying (RZ-BPSK) has been successfully carried out for the first time utilizing cross-phase modulation (XPM) in a passive AlGaAs waveguide. A 10
^-9
-bit-error-rate (BER) preamplified receiver sensitivity gain of ≈ 1 dB was measured for the converted RZ-BPSK relative to baseline RZ-OOK, whereas a penalty of ≈ 2.7 dB relative to baseline RZ-BPSK is explained to be due to cross-absorption modulation induced by nondegenerate two-photon absorption (ND-TPA), as well as to an insufficient nonlinear phase shift.