Multi-point Pump Research Articles

Wavelength-tunable multi-point pump semiconductor disk laser based on an intra-cavity transmission grating

We report a wavelength-tunable multi-point pump scheme of the semiconductor disk lasers (SDLs). By designing an external cavity of SDL with an intra-cavity transmission grating, multiple pump gain regions share the same resonator. The effect of the intra-cavity grating on the output laser power, wavelength, and beam quality was investigated. The emission wavelength could be tuned over a bandwidth of ∼18 nm. With multi-point pumping, we achieve the laser output power with almost no loss, and further improvement is limited by the thermal effect. The changes in the beam are due to the mode selectivity by the intra-cavity grating.

Fabrication of side pump combiners when pumping with a laser diode and a fiber laser

Side pumping combiners are widely used in fiber laser schemes for their high coupling efficiency, low insertion loss, and multi-point pumping capability. However, side pumping combiners perform differently in coupling efficiency when pumping with a laser diode (LD) and a high-brightness 1018 nm Yb-doped fiber laser (YDFL). In this paper, for the first time, to the best of our knowledge, we investigated the different parameters to fabricate the (2+1)×1 combiner with high coupling efficiency when pumping with an LD and a YDFL, respectively. After optimization, the maximum coupled pump power from one single-pump port of the combiner was 1200 W and 2730 W when pumping with a LD and a YDFL, respectively.

The experimental study of a CW 1080 nm multi-point pump fiber laser

In this paper, we report on a CW 1080 nm fiber laser cascaded-pumped by a CW 975 nm diode laser. The fiber used in the experiment has a core diameter of 20 μm (NA = 0.06), inner clad of 400 μm (NA = 0.46), and an absorption coefficient of about 1.26 dB m−1 at 975 nm. An output power of 780 W with an optical conversion efficiency of 71% has been achieved at a pump light of 1.1 kW. To the best of our knowledge, this is the first time that a 1080 nm CW fiber laser has used a cascaded-pump coupler.

Good guess functions for MATLAB BVP solvers in multipoint pumping Yb3+-doped fiber lasers

Including constant, linear function and exponential function, three good guess functions of forward signal power are developed to deal with the difficulty of setting suitable estimates in the multipoint pumping Yb3+-doped double-cladding fiber lasers (YDCFLs) model with boundary conditions using MATLAB BVP solvers. Simulation results show that three good guess functions can get rapidly the exact values of YDCFLs after only one iteration times. Among three good guess functions, conversion efficiency critical guesses of linear functions are more stable than those of constant and exponential functions at different fiber lengths. Furthermore, the more pump points, the smaller fluctuations of conversion efficiency critical guesses in linear functions at different fiber lengths. Conversion efficiency critical guesses of linear functions keep small fluctuations with the increases of pump powers at different points pump.

Theoretical analysis of multipoint pump Yb3+-doped double-clad fiber lasers

A wide-scope multipoint pump Yb3+-doped double-clad fiber laser model including end-pump reflectivity is proposed in detail. The results show that the optimal fiber length decreases as pump reflectivity increasing at multipoint forward or backward pump. The output powers reach to the maximum value when both the input and output end-pump reflectivity chooses the maximum value. The optimum fiber length increases and corresponding maximum output power decreases as side pump point numbers increasing.

Shooting method with excellent initial guess functions for multipoint pumping Yb3+-doped fiber lasers

Excellent initial guess functions for shooting method, providing for setting suitable initial estimates, are developed to solve multipoint pumping high power Yb3+-doped fiber lasers (YDFLs) model with boundary conditions. Simulation results show that shooting method with excellent initial guess functions can get rapidly the exact values of YDFLs after less than five iteration times. In excellent initial guess functions for signal power and pump power of 3-point pumping or 4-point pumping YDFLs, the guess value of conversion efficiency is greater than or equal to the critical guess value of conversion efficiency. The critical guess value of conversion efficiency is less than 0.21 for all the fiber length in three-point pumping or four-point pumping YDFLs. Comparing to number sequence transition method based on MATLAB BVP solvers of bvp4c(NSTM-bvp4c) and shooting method with answer ranges definition, the simple shooting method with excellent initial guess functions is more reliable and faster for multipoint pumping YDFLs.

Determination of Thermal Conductivity of Liquids by aMulti-Point Laser Pump Method

As an advanced optical method, a multi-point pump method is presentedfor measurements of thermo-physical properties of liquids. Meanwhile,based on the laser-induced thermal grating method, a new theory modelis presented and used to analyse the thermal effects caused by themulti-point laser pump, by which the thermal conductivity of liquidscan be obtained. The results of some typical liquids, such as water,ethanol and acetone, are presented and are consistent with those ofacknowledged values, demonstrating that the multi-point method issimple and useful for characterizing thermal properties of liquids.