Widely tunable mode-locked laser diodes using optical disk filter

We present a scheme for generating high-repetition-rate mode-locked optical pulses within a wide wavelength-tuning range. This scheme utilizes an external-cavity laser configuration with a disk-shaped bandpass filter (disk filter), which is set in the external cavity. The disk filter can tune its transmission wavelength by rotating parallel to the external mirror. This simple wavelength-tuning scheme allows a short external cavity, which is necessary for generating high-repetition-rate optical pulses. This paper describes a preliminary experimental demonstration exhibiting 100%-modulated mode-locked pulses at 8 GHz in the 1535-1587-nm range.