20 GHz, 3.5 ps transform-limited optical pulse generation from a highly stable, tunable actively mode-locked Er-doped fiber laser

Abstract

Wavelength tunable optical sources which can generate ultrashort transform-limited (TL) optical pulses will be required for many applications such as ultrahigh-speed long-distance optical transmission systems [1] and optical measurement systems. To date, 80 GHz, 1.6 ps TL pulses at a tuning range of 1528-1537 nm generation have been reported by temperature-tuned mode-locking of colliding pulse mode-locked lasers [2]. However, it is difficult to synchronize them with another devices and systems due to the utilization of passive mode-locking. On the other hand, actively mode-locked Er3+-doped fiber lasers (AML-EDFLs) are promising because of their easily tunable characteristics of both wavelength and mode-locking frequency. By using an AML-EDFL with a wavelength tunable filter (WTF), generation of 14 GHz, 20-30 ps pulses at 1.52-1.57 nm have been demonstrated [3]. Practical application of AML- EDFLs to the above applications, however, will need stable TL pulse generation over the complete wavelength tuning range. This paper presents the successful demonstration of 20 GHz, 3.0-3.5 ps TL optical pulse generation over the entire tuning range using a wavelength tunable AML-EDFL. Random external modulation of the mode-locked pulses confirmed stable bit-error-free operation.