40nm wavelength tunable gain-switched optical comb source

A wavelength tunable optical comb is generated based on the gain-switching of an externally seeded Fabry-Perot laser diode. The comb consists of about eight clearly resolved 10GHz coherent sidebands within 3dB spectral envelope peak and is tunable over the entire C-band (1530 to 1570nm). The optical linewidth of the individual comb tones is measured to be lower than 100kHz, and the RIN of the individually filtered comb tones (<-120dB/Hz) is shown to be comparable to the entire unfiltered comb (<-135dB/Hz). Besides, expansion of the tunable gain switched comb is achieved with the aid of an optical phase modulator, resulting in near doubling of the number of comb tones. (C)2011 Optical Society of America