Wavelength-shift-keying (WSK) encoded pulses for optical labeling applications

Optical label switching (OLS) is an important approach for building future all-optical networks. In OLS systems, the label and payload can be encoded on the same optical carrier through orthogonal modulation schemes. We demonstrate the generation of wavelength-shift-keying (WSK) encoded optical pulses using spectral processing techniques and their applications in optical labeling systems. We show that the extinction ratio impairment issue for WSK-labeled intensity-modulated optical systems can be solved by using pulse position modulation (PPM) for the payload data, because PPM can guarantee equalized pulse energy in each of the bit period. In our optical labeling experiments with 622 Mb/s label and 9.95-Gb/s payload, the power penalty for the optical WSK label is reduced from 17.5 to 1.6 dB at the bit-error rate of 10^-9 when the payload modulation format is changed from intensity modulation to PPM.