All-optical format conversion and wavelength conversion based on four-wave mixing in HNL-PCF

Abstract

Conversion from a 10 Gb/s non-return-to-zero (NRZ) signal at 1550 nm to a 10 Gb/s return-to-zero (RZ) signal at 1561 nm has been experimentally verified based on four-wave mixing (FWM) in a highly nonlinear photonic crystal fiber (HNL-PCF) without the need of an extra NRZ-to-RZ conversion step. The signal light at 1550nm was modulated by a NRZ electric pulse pattern. The pump light at 1555.540 nm generated by a mode locked laser (MLL) was modulated by a clock signal. When these two lights were controlled strictly and amplified to about 22dBm, the FWM effect happens in HNL-PCF. Two new spectrum peaks were achieved at 1545 nm and 1561 nm respectively. Then the peak at 1561nm was filtered out and discussed. Then we changed the wavelength of signal light from 1543nm to 1569nm. The FWM effect appeared in this whole wavelength range. But the best quality of conversion signal was achieved at 1550nm. So when the signal at 1561nm was filtered out , it was a pulse signal carrying information. The signals at other wavelength were pulse signals without information.