A mode-locked Tm3+-doped fibre laser and amplifier operating at a central wavelength of 1994.3 nm is demonstrated. A thulium oscillator is passively mode-locked by a semiconductor saturable absorber mirror to generate an average power of 17 mW at a fundamental repetition rate of 81 MHz in a short linear cavity. This 2-µm laser train is amplified to an average power to 20.26 W by two double-clad thulium-doped allfibre amplifiers. The pulse energy, duration and peak power is 250 nJ, 23 ps and 9.57 kW, respectively. This represents one of the highest values of average power at ∼ 2-µm-wavelength for picosecond thulium-doped fibre lasers and amplifiers. The performance of the laser system is described in details.
We demonstrated two methods of increasing the bandwidth of a broadband light source based on amplified spontaneous emission in thulium-doped fibres. Firstly, we have shown by means of a comprehensive numerical model that the full-width at half maximum of the thulium-doped fibre based broadband source can be more than doubled by using specially tailored spectral filter placed in front of the mirror in a double-pass configuration of the amplified spontaneous emission source. The broadening can be achieved with only a small expense of the output power. Secondly, we report results of the experimental thulium-doped fibre broadband source, including fibre characteristics and performance of the thulium-doped fibre in a ring laser setup. The spectrum broadening was achieved by balancing the backward amplified spontaneous emission with back-reflected forward emission.
In this paper our results of investigation on a pump power combiner in a configuration of 7×1 are presented. The performed combiner, with pump power of 80–85% transmission level, was successfully applied in a thulium doped fibre laser. The performed all-fibre laser setup reached a total CW output power of 6.42 W, achieving the efficiency on a 32.1% level
Optical sampling based on ultrafast optical nonlinearities is a useful technique to monitor the waveforms of ultrashort optical pulses. In this paper, we present a new implementation of optical waveform sampling systems by employing our newly constructed free-running mode-locked fibre laser with a tunable repetition rate and a low timing jitter, an all-optical waveform sampler with a highly nonlinear fibre (HNLF), and our developed computer algorithm for optical waveform display and measurement, respectively. Using a femtosecond fibre laser to generate the highly stable optical sampling pulses and exploiting the four-wave mixing effect in a 100 m-long HNLF, we successfully demonstrate the all-optical waveform sampling of a 10 GHz optical clock pulse sequence with a pulse width of 1.8 ps and a 80 Gbit/s optical data signal, respectively. The experimental results show that waveforms of the tested optical pulse signals are accurately reproduced with a pulse width of 2.0 ps. This corresponds to a temporal resolution of 0.87 ps for optical waveform measurement. Moreover, the optical eye diagram of a 10Gbit/s optical data signal with a 1.8 ps pulse width is also accurately measured by employing our developed optical sampling system.