Yb-doped Double-clad Fiber Amplifier Research Articles

Experimental and Numerical Demonstration on the Gain and Power Saturation of Yb-Doped Double-Clad Fiber Amplifiers in Multiwavelength CW and Ultrafast Pulsed Operation

Experimental studies on gain and saturation of a Yb-doped double-cladding fiber amplifier accompanied with and interpreted by rigorous numerical simulations are presented. The saturation power, the value, and the spectral asymmetry of the output signal are experimentally characterized in both pulsed and continuous wave (CW) operation, and then, verified and interpreted numerically. Power conversion efficiency and quantum conversion efficiency of the amplifier are measured to be up to 55% and 58%, respectively. It is the first time, to the best of our knowledge, to demonstrate a numerical model for the pulsed operation based on the interaction of vector coupled nonlinear Schrodinger equations and the rate equations of the Yb-doped double-clad fiber taking into account all high-order dispersion parameters and the variation of gain coefficient during pulse propagation. A good agreement between numerical and experimental results is observed providing interpretations to the results. The numerical models and the experimental demonstrations provide guidance for the design and analysis of Yb-doped double-cladding fiber amplifiers both in pulsed and CW operation.

240 W narrow-linewidth Yb-doped double-cladding fiber amplifier operated in the 100-ps pulse regime

High average power picosecond (~ 100 ps) lasers with narrow-linewidth are in great demand for some specific applications. In this paper, a 240 W Yb-doped double-cladding fiber amplifier system at 1064 nm delivering 112 ps pulses at 40 MHz repetition rate was demonstrated. To prevent possible double-cladding fiber damage, a bandwidth-limited (0.1 nm) fiber Bragg grating (FBG) was used to force a stretched pulse-width of 72 ps and a narrow-linewidth of 23 pm. The laser pulses were then stretched to ~ 100 ps after dispersion management and amplified without notable spectral distortion by nonlinear management. The output of the amplifier produces a pulsed energy of 6 μJ, which corresponds to a peak power of 54 kW. The M 2 factor was measured to be about 1.2 at the maximum power of 240 W. The spectral width was 0.45 nm after the power amplification. Further power-scaling was only limited by available pump power.

Signal Pulse Distortion Induced by Stimulated Raman Scattering in High Power Double-Clad Fiber Amplifiers

In this letter, the evolution of the stimulated Raman scattering effect on pulse amplification for an Yb-doped double-clad fiber amplifier is investigated. It is experimentally demonstrated that the generated Raman-Stokes pulses occur together with the signal pulse, which causes severe distortion of the output signal pulse. The signal and Raman spectral components are discriminated and their temporal evolution dependence on peak power is analyzed.

Theoretical study of two-tone single frequency fiber amplifier with gain competition

Introducing the gain competition is an effective way to suppress stimulated Brillouin scattering (SBS) in single frequency fiber amplifier. Steady rate equation describing two-tone single frequency Yb-doped double cladding fiber amplifier with gain competition is deduced based on single frequency amplifier. A theoretical model of this kind of amplifier is set up. With this model, simulation is performed to analyze the influences of wavelength difference between signals, signal power ratio, pump configuration and length of gain fiber on output efficiency of single frequency laser, and the effect of SBS suppression.

Short-Pulse Dual-Wavelength System Based on Mode-Locked Diode Lasers With a Single Polarization-Maintaining Yb:Fiber Amplifier

In this paper, we report on the development of a short-pulse dual-wavelength source consisting of mode-locked diode lasers and a single Yb-doped double-clad fiber amplifier. Two mode-locked external-cavity semiconductor oscillators operating at a repetition rate of 577 MHz with center wavelengths of 1040 nm and 1079 nm are synchronized, producing short pulses that are injected into a Yb-doped polarization-maintaining fiber for amplification. Numerical simulations are used to determine the optimal fiber length and seeding configuration for dual-wavelength amplification in the fiber. Each signal is amplified to an average power of 0.5 W with pulse durations of around 5 ps. Performance issues associated with two-signal amplification in Yb-doped fibers are discussed, as well as perspectives for increasing the wavelength separation of the seed lasers.

Highly efficient 4-W Yb-doped fiber amplifier pumped by a broad-stripe laser diode

A Yb-doped double-cladding fiber amplifier is v-groove side pumped by a 100-microm -wide, broad-stripe, 975-nm laser diode. The amplifier exhibits, separately, 39% electrical-to-optical conversion efficiency, 89% internal optical-to-optical conversion efficiency, 4-W output power at 1060 nm, and a small-signal gain of 53 dB.

High-power superfluorescent source with a side-pumped Yb-doped double-cladding fiber

A compact superfluorescent source based on an Yb-doped double-cladding fiber amplifier is described. The packaged amplifier is pumped at 975 nm by side-coupling emission from a 2.0-W broad-stripe laser diode through an imbedded V groove. The fiber source generates 485 mW of broadband emission centered at 1055 nm with a 41-nm FWHM flat power spectrum.

Compact 1-W Yb-doped double-cladding fiber amplifier using V-groove side-pumping

A compact packaged fiber amplifier was constructed using a Yb-doped double-cladding fiber, which was V-groove side-pumped by a laser diode operating at 975 nm. Under saturation, the amplifier generated 1 W at 1064 nm. The small-signal gain reached a maximum of 50 dB at 1075 nm and was greater than 40 dB in the range of 1042-1093 nm.