We investigate electrical wavelength tuning of a cavity length dispersive fiber ring laser operated in the 1/2-rational harmonic mode-locking condition. By changing the modulator frequency around the optimum mode-locking frequency, a tuning range of 10.45 nm with a tuning rate of 0.067 nm/kHz is achieved. The repetition rate of the mode-locked pulses is twice the modulation frequency (∼1 GHz) and the extinction ratio of the laser spectrum during the full tuning range is above 30 dB. Compared with the conventionally harmonic mode locking, the tuning range is about half reduced but the tuning rate has a same value. The variation of the modulation frequency and the length of the dispersion compensation fiber has a same effect on the wavelength tuning as in the case of conventionally harmonic mode-locking.

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