Wide Wavelength Selectable and High Frequency Precision of All-Optical Wavelength Conversion Using Pump Light Generated from Optical Combs and SSB Modulation

All-optical wavelength conversion based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF) with wide wavelength selectivity and highly precise frequency controllability was investigated in combination with pump light generated from optical combs and single-side-band (SSB) modulation. Using multiple carriers, optical combs generated using LiNbO
₃
phase modulators and an SSB phase modulator, pump lights were precisely controlled with a frequency range of 580 GHz and frequency shift of 1.25 GHz. The frequency difference of the pump lights from the ideal one was less than the resolution of an optical spectrum analyzer FWM was performed for single-polarized 10 Gbaud NRZ-QPSK signals in combination with the generated pump lights, and clear eye-openings and constellations for idler signals were achieved. Moreover, a bit error rate (BER) of <3.8 × 10
⁻³
for all idler lights was achieved. Conversely, in the case of the 1.25 GHz controlled pump light, the constellation was distorted, and the BER was saturated at 2.0 × 10
⁻⁴
. In addition, the limit of wavelength convertible bandwidth was investigated to determine the condition for selecting the frequency of wavelength conversion applicable to wavelength defragmentation in the metro/core networks. From the experimental and analytical results, the maximum frequency spacing between the signal and pump was found to be 1403.125 GHz, limited by the wavelength conversion efficiency of the HNLF, whereas the minimum frequency spacing was found to be 25 GHz, restricted by the crosstalk between the signal and pump light that could not be eliminated using the bandpass filter.