Guobin Feng

Tm-Ho co-doped fiber-based high repetition rate passive Q-switching of an Er-doped fiber laser

An all-fiber Q-switched Er-doped laser is built with a ring cavity. Stable Q-switching is demonstrated with a Tm–Ho co-doped fiber saturable absorber. The maximum repetition rate of the laser system reaches 42 kHz, which is much larger than that with Tm singly doped fiber saturable absorbers. Analysis shows that interaction between thulium and holmium ions is the main reason for this high repetition rate operation.

Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail.

A Tm–Ho codoped fiber based 38 nm wideband wavelength tunable passively Q-switched Er-doped fiber laser

Exploiting a piece of 0.2 m long Tm–Ho codoped fiber as the saturable absorber, we demonstrate a wideband wavelength tunable passively Q-switched Er-doped fiber laser. The Tm–Ho codoped fiber has a wide absorption band around 1550 nm, promising wideband Q-switching of Er-doped fiber lasers. With a Fabry–Perot tunable filter, stable passive Q-switching is observed in a wide wavelength range from 1535 to 1573 nm. The repetition rate of the laser system is tunable with both the pump power and the lasing wavelength in the range between 0.5 and 50 kHz.

Super-flat supercontinuum generation from a Tm-doped fiber amplifier

Super-flat supercontinua are generated from a double clad Tm-doped fiber amplifier. Two different laser configurations are investigated and compared. In the direct-output configuration, the long-wavelength edge of the supercontinuum spectra is extended to beyond 2.65 μm with a 10 dB bandwidth of 740 nm. In the passive pigtail configuration, the generated supercontinuum features excellent flatness with an intensity difference smaller than 1 dB in the wide central spectral range from 1.98 μm to 2.41 μm.

Modeling of Tm-Ho codoped fiber saturable absorber based passive Q-switching of an Er-doped fiber laser

A theoretical model concerning the Tm–Ho codoped fiber saturable absorber based passive Q-switching of an Er-doped fiber laser is established. Comparison with the Tm-doped fiber saturable absorber is described and discussed. Numerical results indicate that, compared with a Tm-doped fiber saturable absorber, the Tm–Ho codoped fiber saturable absorber shortens the lifetime of the 3F4 energy level and improves the operation of the laser system.

Gain-switching and gain-switched mode-locking operation of a Tm/Ho co-doped fiber laser

Pumped by a 1550 nm fiber laser, a gain-switched Tm/Ho co-doped single-clad fiber laser is built with a linear cavity. Stable gain-switching is achieved with the repetition rate ranging from 2 to 150 kHz. The highest peak power is 11.1 W with a pulse duration of 130 ns. Increasing the pulse energy of the pump, gain-switched mode-locking is attained with a sub-pulse repetition rate of 20 MHz and a pulse duration of about 10 ns; the peak power of the gain-switched envelope is about 4.6 W.

Experimental investigation of gain-switched Tm?Ho Co-doped single clad fiber lasers

Gain-switched Tm?Ho Co-doped single clad fiber lasers are investigated with in-band pumping. The output ratio and cavity length are varied to investigate their impacts on the output pulses. The shortest pulse is 83.4?ns with a peak power of 10.5?W generated from the 3?m long laser cavity with 50% output ratio. At high pump pulse energies, gain-switched mode-locking operation is observed with a mode-locking repetition rate of tens of MHz, determined by the cavity length. The duration of the mode-locked pulse is no longer than 10?ns.

Development of a 2 μm Tm-doped fiber laser for hyperspectral absorption spectroscopy applications

The hyperspectral absorption spectroscopy is attracting more and more attention as this technique enables continuous wavelength sweep over a whole absorption band, rather than one or several discrete absorption lines. Owing to the H2O possesses much stronger and more abundant absorption lines in the 2μm region, this work develop a widely tunable, narrow linewidth Tm-doped fiber laser around 1.87μm for the application of combustion diagnostics. The laser wavelength tuning range is designed from 1850 nm to 1890 nm to overlap the strong absorption band of H2O, and the laser linewidth is further narrowed to 0.04 nm by a fiber saturable absorber. With this laser system, demonstration experiments are implemented for the continuous detection of H2O absorption lines. Detailed absorption peaks of H2O from 1866 nm to 1879 nm are detected and well-resolved. The measured absorption spectrum agree well with the theoretical computation derived from HITRAN2012 database quantitatively, verifying this laser system ready for hyperspectral absorption applications.

Modelling and characteristics of actively Q-switched Er-doped fibre laser with Tm-doped fibre saturable absorber

Abstract A theoretical model concerning FSA-based active Q-switching is developed. And, characteristics of the active Q-switching operation are investigated and compared with the traditional passive Q-switching operation. Numerical results demonstrate that the active control of the repetition rate of FSA-based Q-switching is attainable. And, stable active Q-switching could be obtained from both no lasing state and stable passive Q-switching state.

Improving the repetition rate of Tm-doped fiber saturable absorber based passive Q-switching

Two possible methods for repetition rate improvement of Tm-doped fiber saturable absorber based passively Q-switched Er-doped fiber lasers are reviewed. Simulations show that both methods are effective.