Kecheng Lu

Tunable high-peak-power, high-energy hybrid Q-switched double-clad fiber laser

A cw laser-diode-pumped Yb-doped double-clad fiber laser operating in a hybrid Q-switched regime was demonstrated. The output pulses had a duration as short as 4.2 ns, a tunable wavelength range from 1080.8 to 1142.7 nm, and a linewidth of less than 0.05 nm. Maximum peak power of approximately 175 kW and single-pulse energy of 1.57 mJ were obtained.

105-kW peak-power double-clad fiber laser

A diode-pumped Yb-doped double-clad fiber laser operating in a Q-switched regime is described. By exploiting pulsed pump light and stimulated Brillouin scattering of the gain fiber, a peak power of 105 kW has been demonstrated, which is an order of magnitude greater than that of conventional Q-switched fiber devices. Pulse energy of 0.5 mJ and pulse duration of 5 ns have been achieved.

Narrow-linewidth widely tunable hybrid Q-switched double-clad fiber laser.

A laser-diode-pumped Yb-doped double-clad fiber laser operating in a hybrid Q-switched regime has been demonstrated. With pulsed pump light and stimulated Brillouin scattering of the gain fiber as the Q-switching mechanisms, the laser generated nanosecond pulses with a stable repetition rate. A single-pulse energy of as much as 143.1 microJ with a peak power of 28.6 kW was obtained. Use of an external-cavity diffraction grating in the Littman configuration permitted tuning of the laser wavelength over a 15.7-THz range from 1080 to 1140 nm, and a linewidth of 0.04 nm over the whole tuning range was achieved.

Highly efficient dual-wavelength ytterbium-doped fiber linear cavity laser based on cascaded fiber Bragg gratings

A highly efficient dual-wavelength ytterbium-doped fiber linear cavity laser is experimentally demonstrated. Two cascaded fiber Bragg gratings are used as the wavelength selection component. Stable dualwavelength operation and wavelength-switching modes can be realized by appropriately adjusting the polarization state of the intra-cavity light and the reflectivity of the laser cavity. For dual-wavelength operation, the power difference between the two wavelength lasers (1029.7 and 1040.4 nm) can be less than 0.6 dB and the signal-to-amplified spontaneous emission (ASE) ratio is more than 52 dB. The slope efficiency of the laser is as high as 63.9%.

Self-Q-switched Er-doped fiber laser

In this paper, a self-Q-switched Er-doped fiber (EDF) laser is reported, which employs stimulated Brillouin scattering (SBS) in single-mode (SM) fiber as a passively Q-switched mechanism. The stable nanosecond magnitude optical pulses were obtained. Pulses with peak power 800 mW, pulse width 2.2 ns and repetition rate about 64.5 MHz could be achieved, when the pumped power was 88.0 mW. A few factors that affect the pulse characters are studied.

Output characteristics of high-power double-clad fiber laser

The output characteristics of linear cavity Yb-doped double-clad fiber laser have been studied theoretically and experimentally. Analytical expressions are evaluated for threshold pump power, output power and slope efficiency of the laser under steady state conditions. The expression of minimum of fiber length for designing a linear cavity Yb-doped double-cladding fiber laser has been given. Then, the Yb-doped double-clad fiber laser has been investigated experimentally. By exploiting various output coupler, output power, threshold pump power and the slop efficiency have been measured. Comparison between the experimental results and theoretical data has been performed. They are in good agreement with each other.

Self-Q-switched double-cladding fiber laser based on SBS

A cladding pumped self-Q-switched Yb3+ fiber laser is described in this paper. By exploiting fiber nonlinearity -- stimulated Brillouin scattering (SBS) in the fiber laser cavity, we demonstrated a series of stable pulses with the full width at half maximum (FWHM) about 2 ns and repetition frequency about 29.4 MHz.

Study on the output characteristics of a large-core Yb-doped double clad fiber laser

The output characteristics of a large-core double clad fiber (DCF) laser are experimentally investigated in this paper. The fiber laser is fabricated with 5m Yb-doped DCF that consists of a 30μm diameter core and a 400/340μm D-shape inner clad. The measured spectra show that the wavelength of laser is not stable at low pump levels, and the wavelength tends to be stabilized at 1074nm until the pump power is increased to a level far over the threshold. The maximum output power of 7.2W is obtained at an input pump of 11W with a FWHM of about 6nm. The slope efficiency and the total conversion efficiency are 84% and 65.5%, respectively.

DBR Yb-doped double-clad fiber laser operating at 1.06 μm

An all-fiber Yb-doped double-clad fiber laser based on distributed Bragg reflection (DBR) with fiber Bragg gratings (FBGs) is demonstrated. The single transverse-mode wavelength-stable output at 1 .06 µ m is up to 1.18W, with a slope efficiency of 68% and an optical-to-optical conversion efficiency of more than 50%

Conversion efficiency of double-clad fiber laser

The paper reports the theoretical and experimental research of Yb-doped double-clad fiber laser. In the experiment, we use F- P cavity structure. We obtained an output power of 233 mW at a slope efficiency of 79.6% with respect to input fiber power. The total optical-to-optical conversion efficiency is 30.3%. And the output wavelength is 1.078 micrometers .