Optimized one-step compression of femtosecond fibre laser pulses to 30 fs in dispersion-flattened highly nonlinear fibre

摘要

Motivated by applications in spectroscopy, frequency-metrology and optical telecommunications, the development of all fiber-format sources of sub-30 fs pulses around 1550 nm is a subject of much current interest. A number of different techniques for pulse generation in this regime have been reported in recent years, typically involving hybrid soliton-like compression of a primary fiber lasers source using multiple fiber segments with differing dispersion values and/or dispersion slopes [1, 2]. Despite the additional control afforded by hybrid compression, there are nonetheless disadvantages in (i) the need for sometimes difficult-to-obtain non-standard fiber and (ii) the necessity to optimize the lengths and placements of different fiber types. In this paper, however, we show that it is possible to obtain high quality nonlinear compressed pulses using only one segment of readily-available highly nonlinear fiber (HNLF). By directly splicing a very short (7 cm) length of HNLF to the output single mode fiber pigtail of a commercial femtosecond fiber laser, frequency resolved optical gating (FROG) confirms that nonlinear compression results in the generation of 28 fs pulses. This represents an extremely simple modification allowing an essentially loss-free factor-of-three reduction in pulse duration relative to the primary source.