Widely Vernier tunable external cavity laser including a sampled fiber Bragg grating with digital wavelength selection

We demonstrate an easy and efficient step tunable sampled fiber Bragg grating (SFBG) external cavity laser. A small current variation applied to a single electrode induces a step tuning of 15 nm based on the Vernier effect between an SFBG with a comb-like reflectivity and a two-section semiconductor laser diode. Thanks to the low current variation of less than 3 mA in the phase section, the output power remains constant within 0.6 dB at 6 dBm. The side-mode suppression ratio is greater than 40 dB over the whole tuning range.